Category: Antennas

Anything Involving Antennas

Automated Antenna Switch

Fabrication and installation of a network controlled antenna switch. Allows for 2 inputs with up to 6 outputs.


After putting up multiple antennas at my QTH, it was frustrating having to manually switch between antennas. There are plans to add SO2R (Single Operator, 2 Radio) operation and have the option to use the station remotely in the future. I needed some type of automated antenna switch.

Goal is to have an automated antenna switch that can be controlled over the network and/or the internet. In a SO2R or 2O2R (2 operators, 2 radios) environment using two computers, I’d would like each computer to know what antenna the other is using.

After doing some research, there were a couple options.

Commercial Options

4O3A Antenna Genius – Ranko makes some quality products for the serious contester. The ‘Antenna Genius’ has everything I want in an antenna switch. However, it’s quite expensive at around $875USD and that’s just the switch itself. This is way out of my budget.

Team-XCR 4 Way Remote Switch – When I was initially researching switches, I’ve heard about this project but it was still in development. As of writing this article, it appears they are in production.

I wasn’t interested in this project at the time because it was being developed as a 1X4. One antenna input, 4 outputs. I’m looking for a 2X6 configuration and SO2R support

However, it’s very promising. It’s controlled by Wifi (ESP32 Module) with a web interface and uses the coax to power the relays using a Bias-T circuit. For around $250USD (switch + bias T) that’s not bad at all. There is also development being made for a 2X6 which is promising. I’ll be watching this project for sure.

Snaptekk, Remoterigs, DXEngineering and others. – There are many options of automated/remote switching out there but either it didn’t support automated switching what I wanted or the price was just too much

Do It Yourself

It’s possible to do an automated antenna switch yourself but that depends on you value your time. Since I didn’t have much knowledge in creating a RF friendly PCB and don’t know how to create the code for an Arduino or Raspberry Pi project, I looked for people that already done to the work.

I found it’s possible to create a 2X6 automated switch that can be networked controlled if you combine two projects.

KK1L 2X6 Kit

First was the KK1L 2X6 PCB Kit. This has been on my mind for years. I’m aware of many people who have purchased it and use it in their shack without much issue. Ron only sells the PC boards but he does provide a really nice mouser list that you can import into your shopping cart. Makes it very easy.

However, I wasn’t really a fan of his controller and held off purchasing the 2X6 because of it. Nothing against the design. It’s not what I wanted. During my research I was unaware there can be multiple ways to control the relay board.

FreqEZ II By K8UT

While researching another project (MORRTY) and from a suggestion from a fellow ham on IRC, I came across the FreqEZ II by Larry, K8UT (Will call it FEZ2 from now on) I didn’t think much at first until I clicked on the link. It had everything I wanted in a controller. It utilizes a Raspberry Pi (RPi) and to top it off, he developed hardware that uses the RPi’s GPIO pins. For $50USD, the price was worth it. I had a few Raspberry Pis laying around from other projects (ADSB, RTLSDR).

Larry also developed software for Windows that could take data from BCD, UDP broadcasts from certain logging software (N1MM, DXlabs) to automatically switch antennas and you can also control it manually through the software.

Will They Work Together?

Yes they will! Even Ron (KK1L) was interested in the FEZ2 and was implementing it into his station. Larry (K8UT) also assured me that it could work but at the time wasn’t sure about preventing the hardware and/or software from having both radios choose the same antenna.

Ron assured me that even if something happened with the software/controller, it won’t be able to connect both radios (inputs) to the same antenna (output) as designed by the hardware.

Larry (K8UT, FEZ2 dev) was currently developing features such as constraints to also prevent multiple radios from choosing the same antenna. For anyone planning to follow along, The FreqEZII wasn’t developed FOR the KK1L 2X6. It was developed for all sorts of hardware and applications.

The Goals

I have two goals in mind for this project. One is for a 2A (2 Station) field day option and the other is for home.

Field Day layout block diagram
Field Day Option With 2X IC-705, 2 PCs, Router/Switch, KK1L 2X6 w/ FreqEZ, BPFs, Triplexor and Antennas (Goal 1)

I help out with a small (private) field day operation. It started as a simple 2 station effort with wires in the trees. Of course we complicate things over the years by adding a tower with a beam and multiple antennas. With the station and antennas optimized to our liking, only issue we had was switching antennas. My goal for 2022 was to automate the process

SO2R block diagram layout
Option 2: This would be my “dream” setup

The above “option 2” diagram shows my dream setup. Dream is the 6600 with PGXL. However, it might end up being my current flex 6400, used HF solid state rig and possibly 2 amplifiers or something from SPE.

For now this project will be focused on Option 1 which is for Field Day use since it’s needed and promised. We’re going to focus on building the 2X6 relay board and getting it to work with the FEZ2

KK1L 2X6 Build

Ron had boards in stock and thankfully mouser had all the parts in stock as well. Ron provides a list on his website that you can import to your mouser shopping cart. Be careful because he does list optional parts and he recommends an enclosure that may or may not work with this exact project.

Ron and Mouser shipped very fast and received both items within a week. Ron has included assembly instructions but I prefer the ones from his website.

If you follow the instructions, the build is quite straight forward. Be sure to follow it carefully as components have to clear other components. Only thing I did different was fabricated spacers for the SO-239 mounts instead of using nuts that he specified.

spacers for relay board
1/8″ spacers made for the KK1L
finished relay board
Completed 2X6

FreqEZII Build

The build itself was easy. I purchased the FEZ2 hat that installs on any raspberry pi that has a 40pin connector. Well worth the money if you ask me. Just plug the hat onto the Raspberry Pi. Getting it to work with the pi is where all focus will be.

Larry suggests using a Pi4 or a Pi3 and provided detailed instructions. However at the time of starting this project, Raspberry Pi’s are quite difficult to get. I personally have a few Raspberry PI 1 B+ units laying around. They have the 40pin connector and figured to give it a try. The Pi Zeros with 40pin headers could work as well.

His instructions are for those who don’t know their way around a Raspberry Pi, Linux or using a CLI (Command Line Interface). Due to the limited resources and limited CPU of the Pi 1, I didn’t want to install a full GUI (Graphical User Interface like with Windows). This is where I deviated from Larry’s instructions. I strongly suggest if you are following along to use Larry’s instructions. I know enough about linux to get myself into trouble.

As of writing this article, Larry has been very active in updating the software and the older Pis may or may not work after a recent major update.

I’ll keep this article updated as I go along.

Putting It All Together

With the 2X6 built and the FEZ2 in working order, we can now put both of these projects together. This will mostly involve wiring. This might change depending on exactly what you want to do with your project.

The KK1L uses 12Vdc to power the relays. However, the RPi require 5Vdc. Since most shacks use 12-14Vdc, you’ll need to convert 12v to 5. You can do it yourself but I went to Amazon and found a converter made for the RPi.

Even though I was initially confused at first, wiring the relay board to the FEZ is very simple. The FEZ has 16 outputs split into two bays. You’ll only need 12. 6 for “Radio A” and 6 for “Radio B”. What I did was use the first 6 outputs from the FEZ to feed all the “A” ports on the 2X6 and used the 2nd bay to feed all the “B” ports on the 2×6. Below is a diagram showing what I did

Relayboard and controller block diagram
Diagram showing how I wired the FreqEZ to the 2X6 relay board.

The KK1L 2X6 relays use 12v. The 12V+ from the PSU is going to both “C” (control) banks as they can be operated independently.

Wiring

You’ll see that I also wired the 12v-to-5v converted directly to the GPIO pins of the RPi. I did this because I purchase the wrong converter and had a different USB type end. If you decide to solder 5v directly to the GPIO pins of the Pi, please confirm that you are soldering to the correct pins and take care to prevent shorts. Not pictured in my diagram is inline fuses. I have one prior to the case and I added one on the 5v side to protect the pi.

As for the wire itself, I used CAT6 cable. The relays are not requiring a massive amount amperage. I used two “short” sections. One for antenna “A” and another for “B”.

FreqEZ2, Raspberry Pi and KK1L 2X6 Test Setup

Testing went okay. Loaded the FreqEZ2 windows software and was activating and de-activating relays to confirm operation. This allows me to stuff everything inside of a case and continuing setting up the software which I feel is the 2nd “battle” of this project.

Enclosure Fabrication

automated antenna switch enclosure

This is where you won’t be able to follow along. I did not purchase the enclosure that KK1L suggested as I wanted room for a raspberry pi and a divider hoping to keep RFI away from the Pi and hat. The enclosure in KK1L’s mouser BOM may or may not work with both the Rpi and Relay board in the same enclosure. I can’t confirm this. Hammond MFG does make a larger enclosure that you can purchase on mouser. I can’t confirm if it will work 100% as I went with a custom fabricated enclosure. For those who want to fabricate their own enclosure, KK1L provides drawings with the hole layouts on his site. The pi and relay board are in separate enclosures.

Inside of enclosure without relay board
Enclosure without relay board showing RasPI and converter
Enclosure with separator installed
Enclosure with RasPi covered up to help with any possible RFI reduction.

Trial By Fire

With everything together, it would be best to test things out independently within its own environment before implementing it into a station. Make sure everything is working properly and try everything possible to make it not work.

I’ve confirmed that the software and hardware worked. At first, There were some issues when it came to networked operations using multiple copies of the windows software. Larry and Ron were quick to help. Larry even updated his software because of some of the issues I’ve had.

With things appearing to work properly, I should have put RF through it and tested everything again but of course that wasn’t done. I decided to use ARRL Field Day 2022 to be the first real test.

If this works throughout the entire weekend then I considered it a major success considering the quick implementation. Worst case is we go back to manual switching. However, I don’t want that to happen.

There was one issue I had setting up. However, it wasn’t related to the switch itself . It was related to trying to use the switch on an established network and accidentally setting stricter firewall settings on the PCs controlling the switch.

First Run

automated antenna switch complete
Antenna Switch In Action

Started FD with the network and firewall settings issue but it didn’t really get in the way. After the first hour we finally figured out what was causing the issue. Ended up turning off the PC’s firewall. Next year we’ll make sure the PCs join the wifi network as a “Private Network”.

I configured the switch to work based off N1MM+ UDP broadcasts to automatically switch antennas. We’re using Icom 705’s that are also connected to N1MM for control and to pass data back and fourth. This allows the operators to focus on operating and don’t have to learn the FEZ control software.

After that minor issue cleared up, the FEZ and KK1L switch worked flawlessly throughout the entire weekend. Even during power cycles. The operators that were using the stations enjoyed not having to manually swap coax or remember which coax is which.

Overall Thoughts

Overall it was a success and it will be used for field days and other events to come. Also plan on building one for my shack. Larry and Ron were a pleasure to deal with and I think it’s an excellent combination. If you’re looking for a network/remote controllable 2X6 antenna switch and you are willing to put in the work, the FreqEZ and KK1L 2X6 is a perfect, cost savings project that you would be proud to use.

As I was typing this article, Larry (K8UT, FreqEZII developer) has came out with some exciting news. He moved the project to it’s own website and even developed another piece of hardware that makes use of the Pi ZERO. He is continually working on this project.

I’m also aware that Ron is in the process of developing PCBs that will implement FEZ.

Thank you for reading. 73 DE NT1K

Portable Operations – What I Carry

I guess I should post up something that isn’t about contesting. I am often asked about my portable setup so I figured just to post it up here to show all.

This setup works for me but it might not work for you. I attempt to pack as small and minimal as possible when it comes to portable. I know some who pack everything including the kitchen sink so opinions will vary.

Here is my portable setup

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That’s basically it. Here is a break down of the above picture

Elecraft KX3 – This is the most important part. When I was getting into portable operations, I wanted a radio that wouldn’t waste energy. The KX3 was just released and it met everything that was on my list. It can use AA batteries, the antenna match option works wonderfully, it has multiple modes and nice sized screen. I will admit it was expensive but I felt if I use it 50 times, it would be worth the cost. If the KX3 is not an option than an Yaesu FT-817 will do or those CW QRP kits like KD1JV’s MTR/Sprint radios.

G5RV Jr Antenna – Some people question as to why I went with a G5RV jr antenna and the answer is simple as that I had one laying around so why not use it. When stored properly, it doesn’t really take up much room. I had great luck with it so I kept using it.  However the one I had wasn’t suited for portable use. It was breaking apart and used solid core wire for the 450ohm “ladder” line.

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I ended up making a smaller one. I made custom end insulators that act as winders. I also used polystealth wire and a BNC port. The new antenna is much smaller and is somewhat easier to deploy.

Here is the radio with the G5RV jr working some DX while portable in Vermont.

EARCHI end fed antenna – This is my other antenna that I use if I want to be very quick or the local environment prevents me from using the G5RV. It’s just 31 feet (around 15m) of wire that is hooked up to a 9:1 UnUn. Even though I much prefer the G5RV, the end fed works okay.

portableKX3SC

Here is the Endfed on the beach in South Carolina. Salt water works wonders. Setup was less than 5 mintues and it didn’t take up much room in the car.

Jackite Telescoping Kite Pole (Mast) – For a long time I would tie rope to rocks and throw them over tree branches. In some locations there were no trees which made it much more difficult. Even though a portable mast is bulky for me, I think it’s necessary. I ended up going with Jackite’s 31′ Fiberglass pole because it was 31′.  It is designed for windsocks/kites but hams use it for antenna supports. It made portable communications much easier.

kitepolesota

Should have added something for scale. My only complain is the caps can easily come off which sucks when you’re in the middle of the woods when it happens. Little bit of electrical tape does the trip.

Logbook – I use two logbooks during operations. One is just a regular notebook that can fit in my bag and the other is the voice recorder on my phone. That way I can make youtube videos and also go back if I messed up my paper log. The notebook is just full of scribbles. Soon as I get home I enter them into the proper logging software or website.

Foam Pad – I carry a foam pad that gardeners would kneel on. It provides some cushion and ground isolation. It’s a must have and fits nicely in my bag

Misc Antenna Items – I usually carry a roll of RG-58 with BNC ends, tent stakes, small spool of nylon high vis mason rope and bungee/tie down cords. I avoid using any type of nail or screw. I do not want to disturb the environment. I say the stretch/bungee cords is what I use the most to secure the mast to trees and/or benches.

Dedicated Bookbag – When I was at costco I saw some bookbags on sale for $15USD and couldn’t resist. I dedicated it to portable operations since I usually don’t plan my operations.  When I get home after each portable operation, I make sure to organize my backpack and have it ready for the next time. I leave almost everything in the bag so I can almost grab and go since I decide to go out usually at the last second.

Future Plans

I’ve been trying to learn CW for a long time now. I am getting better but once I am confident that I can do CW without any kind of assistance, I will go out with a smaller rig and different antenna. I want a smaller light weight pack. I would also like to find ways to go without a mast but there are times where the area is unknown.

Thanks for reading,
NT1K

New Beam In The Air and I’m Swinging It Like I Just Don’t Care.

Since I got my first HF station up at my house, I’ve only used the G5RV (Both Jr. and fullsize) and the 10M dipole in my attic which is surrounded by aluminum siding. With these antennas I’ve been able to make thousands of contacts. I’ve manged to get  basic DXCC and WAS awards. Even though a lot of people harp on the G5RV, it provided me countless hours of contacts and I think  it was well worth putting up. I would still suggest the G5RV or its variants to others.

However I think I pushed the G5RV as far as it could go. The antenna has since stretched. More ladderline is laying on the ground. New entities are getting harder and harder and there are bands I haven’t really explored. 10 Meters on my G5RV hasn’t been really good to me and the dipole wasn’t going to cut it since it was basically surrounded by aluminum. I was also starting to get bored. I would only hop on to see if I can work a DX expedition or random JT-65 contacts. I needed an upgrade.

My first solution was to get a multiband vertical. In 2011 I purchased a used Butternut HF9V at a local hamfest. In 2013 I finally buried some coax and installed the antenna with a bunch of radials.

gBdIlsE

Upon getting it on the air, I found that it wasn’t really a performer. In a lot of cases, the G5RV was much better. The HF9V didn’t really give me the “WOW” factor I was looking for. But it work so it stays in my backyard. I needed something better. I needed a beam.

What Beam Should I Get?

That was one of the many questions I was asking myself. I didn’t want anything massive or anything that would require a large tower or rotor. I kept focusing on a Hex Beam type antenna, log periodic or a 3el tri-band antenna like the Mosley TA-33jr or Cushcraft A3S. I ended up going back and forth between the K4KIO type hex beam or TA-33.

The Hex Beam offers more coverage. It’s possible to get 20 through 6 meter coverage which includes the WARC bands. That’s 6 bands. In simple terms, it’s basically a 2 element beam with the elements folded in such a way that it still works. There is a claim 5dbi  (or 2.95 dbd) gain. The claimed F/B (Front to Back) varies from approx 25db to 30db depending on the band.  So in theory with perfect conditions and zero loss, if the antenna was fed with 100W, it would radiate around 192 watts. The hex beam would also attenuate signals from the back of the beam by 27db.  This allows you to hear signals better in the direction it’s pointed in.

The TA-33jr can only really be used on 20, 15 and 10 meters. The antenna could be adapted for other bands with the addition of the WARC kit. The TA-33jr has anywhere from 5.8 to 8.0 dbd  or claimed gain (or  7.95 to 10.15 dbi gain) and has a claimed front to back ratio of 20db. So once again, in theory with perfect conditions and zero loss, if the antenna was fed with 100W it would radiate anywhere from around 380w (on 20M) to around 631w (on 10M) and would also attenuate signals from the back of the beam by 20db

These comparisons are based from figures provided by manufacturers. That doesn’t mean that is how the antenna will perform in real world conditions. Things like height about ground, the type of ground, coupling to nearby antennas or other thanks and losses from coax and connectors play a major role in the performance and efficiency of the antenna.

On paper, the TA-33jr offers more gain on 10, 15 and 20 and looks easier to assemble but the multi band hex type beam has a better front to back (F/B) and offers more gain on the WARC bands. The TA-33 types of antennas have been in use much longer than the Hex type. If you were purchasing a beam on a small budget, the TA-33 type of beam would be much cheaper on the used market because they have been in use for decades (at least 50 years). I’ve seen TA-33 in decent shape for as low as $100.

How am I going to Mount The Beam?

No matter what I decide, I would need to mount the antenna to something. My first option was to obtain a tower and have it bracketed to my house at about 70′ in height. However that did not meet XYL approval because of possible guy wires in the yard and I want to keep my neighbors happy. Since a bracketed tower is out of the question, my next best bet was a roof mounted tower. My house at the peak is approx 40 feet above the ground level. With a 9ft roof tower and decent mast, I could get my beam 50 feet above the ground.  So a roof tower it was.

Going Shopping

I priced out a new Hex Beam from K4KIO, 9.5′ Tower from Glenn Martin, A new Rotor and Rotor Controller (Yaesu G-450), Mast, thrust bearing and cables. The price tag totaled almost $2,000. That is something I can not afford. However I was able to find a used TA-33, 5ft tower and rotor for much cheaper locally. I ended up purchasing the TA-33 package over the hexbeam. I am losing out on the WARC bands but the price made up for the loss.

A Pile Of Aluminum

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Upon receiving the antenna, I noticed right away it’s not a TA-33 that I thought I was getting. The Boom is 2 inches in diameter and longer than the TA-33jr. After a little bit of investigation, I found that the antenna is a CL-33 or a TA-33 Classic. The CL-33 is 6ft longer and provides slightly more gain and slightly higher F/B ratio compared to the TA-33jr. I was trying to go as small as possible but since I already have the beam, it will have to do.

The tower and thrust bearing was in great shape but the rotor appears to seen better days. The terminals were rusty and the rotor would “struggle” in certain areas when turning it without an antenna attached. I need to restore the rotor.

20131231_093936 20140102_161827

I stripped the rotor down and found a group of really rusty ball bearings. I soda blasted and powder coated the case, ordered new ball bearings, new brake parts and a new style connector. After some cleaning and re-wiring, the rotor is good as new.

The antenna was taken apart and traps were checked for debris and broken parts

20140801_185843

For the most part the traps were clean but some of the coils had cracks and even chunks of plastic missing. I ended up filling the cracks and voids with epoxy. Worst case is that I would have to get replacement traps. Being such a well-known antenna, it’s little easier to find parts.

After repairs I cleaned all the aluminum with scouring pads and applied an Anti Oxidation grease that will prevent the sections of elements from sticking to each other. I also applied anti-seize lubricant on clamps and other things.

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I did a test fit to make sure everything is working and bolting correctly to the tower. You will notice a different rotor.

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I have went with a Yaesu G-450 rotor because it was almost new and got it for much less. You will see WRTC spray painted on the rotor. It was used during the World Radiosport Team Championship (WRTC) here in New England. It’s not as heavy-duty compared to the Ham IV but I feel more safe using it.

There was only one concern I had with the tower and that was protecting the thrust bearing. I didn’t want rain, snow and ice to build up around the TB so I designed and fabricated a cone to slip over the TB shedding away anything from above.

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Now it’s time to test the boom mounted to the mast

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So far so good. The only concern I had was that the cone now provides a great home for hornets. I guess we’ll see.
The tower and antenna are now ready to be mounted on the roof.

Hurry Up And Wait… Now Hurry Up!

House

Now we have to get the tower mounted to my roof. I decided the best course of action is to mount the tower towards the rear of my house. That will allow the beam to clear a near-by tree and it makes it less visible from the street. Two trees in the front of my house hides the tower and beam quite well. I might provide some signal problems but we’ll see. I planned on using 10″ carriage bolts going through the roof into my attic and brace it using 2×4’s and a metal channel spanning over multiple rafters. I designed everything in CAD and put it through stress analysis. According to the results, it looks good.

Here is the problem. I don’t like going up on my roof. When I installed my X510, I almost fell off the roof and sort of been scared since. I don’t have the proper equipment to go up on my roof safely. the 10:12 pitch takes a toll on me. I am also stubborn and have a “do it yourself” attitude so I put the project off. It was planned to be put up in April before the New England QSO Party, but it’s now November and I still don’t have a tower on the roof.

I needed some roof work done before it got real cold outside. I had to hire a roofer to install venting and asked if he could install the tower at the same time.

20141101_163234

Thankfully he agreed and there is now a tower on the roof. Ignore my leaning diamond X510. It could have been prevented from leaning if I used a couple of self tapping screws. Due to the weather and hourly cost of the roofer, I decided not to install the antenna on the same day. Let the neighbors sort of get used to the tower on top.

TowerBrace

From inside my attic, I braced the antenna using 2X4’s and a large metal U channel covering 5 rafters. Very sturdy.

I Wanted To Get It On The Air

There is an upcoming 10M contest in December that my local club is involved in. I wanted to participate and I know my G5RV, HF9V or my 10M dipole wasn’t going to perform. I finally folded and contacted members from my local club to come help me install the antenna. A lot of people responded and on cold windy Sunday in December, a bunch of people came to my house to help install the beam.

TowerEd

A Major thanks to Ed, KB1NWH for staying up on my roof for hours.

We removed the Diamond X510 as it would be in the way and decided to assemble the beam on the roof since the tower isn’t tall.  We then installed the boom, each element and then the Diamond X3200. I didn’t want the X510 on the mast as it’s a much larger antenna.

NewBeam1

Finally. I now have a beam! There is still cable work to be done but everyone was able to leave in just a few hours. I was on the air just after noon.

I would like to thank Ed (KB1NWH), Jim (KK1W), Steve (N1SR), Frandy (N1FJ) and Dave (AA1YW) for taking time out of their life to help me get an antenna on the air.

 

What’s the difference?

I never had a beam before and I have no clue how one would perform at my house. I hooked my radio up to a A/B switch so I can switch between the G5RV and the Beam. The bands were not great when I finally got on the air but I was able to hear a lot of West Coast stations on 20M. I had a real hard time getting my signal out west and was amazed to see the difference. Stations that were S2 on the G5RV were coming in S8-9 on the beam. The front to back ratio was okay. I was pointed to EU and hearing a Texas station at the same time. When pointed to EU the Texas station was S7 and when I turned the beam toward the Texas station, he became a S9+. I will have to do more comparisons.

Here is a quick and dirty A/B video I did for a Fellow redditor. I should have found a week station but that will be for another video. I just wanted to show the obvious difference in antennas.

Contest Time

Having the beam on the air for the ARRL 10M contest was great. I have never participated in it and felt the beam proved to work quite well. 10 meters was open to Europe both Saturday and Sunday morning. I did about 100,000 points which is not bad considering I operated only 10 hours using low power (Around 100W) and was not using spotting assistance. I knew I would not win SOHP so the amp stayed off.

Overall Feelings

I should have done a beam much sooner. Or maybe I shouldn’t. Starting off on wires provided a challenge. With the wires I was able to make contact with a lot of operators and even won some awards and contests. Now that I have a beam, hopefully it opens up the door to even more contacts with those ham radio operators around the world. My signal will now be a little bit stronger and I will be able to hear farther away. Getting the beam on the air has renewed my interest in actually getting on the air.

Thank for reading,
Jeffrey Bail (NT1K)

Portable Antennas: The EARCHI End Fed

In the search for the “Wonder Antenna” that is small, portable and easy to setup, I’ve decided to build an Endfed antenna using a 9:1 match. This antenna has been made popular by the Emergency Amateur Radio Club of Hawaii (EARCHI). It consists of 30ft of wire fed into a 9:1 UnUn (Unbalanced to Unbalanced).

Plans for the Antenna are available from EARCHI’s website 

I’ve been wanting to make the antenna for quite a while but I’m lazy when it comes to ordering things online.  During the spring of 2013 I went to a regional hamfest located in New Hampshire hoping to find the T106-2 toroid that was called out for in the plans. I saw a bunch of red toroids and decided to purchase them hoping it was the correct mix and size.

I ended up with what appears to be a T130-2 toroid. It’s a little bit bigger than the T1o6 but uses the same mix.

The Build

It wasn’t that bad… If you follow the instructions the build only takes about 15 minutes or so. I mounted everything inside of a plastic tooling container. Instead of using a chassis mount SO-239 I went with a small length of RG-58 coax with a BNC at one end. The reason I did that was because there is always a strong chance that I’ll forget the coax and could at least use the pig tail connected to the radio.

IMG_0674

 

The plan is to get this into even a smaller container.

Let’s hook it up to the Analyzer.

Before attaching it to my radio, I wanted to hook it up to the analyzer just to make sure I have the correct toroid being used. When it comes to buying toroids at hamfests, you could be taking a gamble unless it’s clearly marked. I might have purchased a different type even though it’s red in color.

IMG_0672

What I’ve done is hooked up a bunch of resistors to the output and ground of the unit. The resistors should add up to 450ohms. Since it’s a 9:1 balun (or unun in the end use),  9 goes into 450 50 times which we should see 50ohms on the otherside if all is correct.

EarchiScreenShot

With the 450 ohm load. The analyzer is see approximately 50ohms across the HF bands allocated for Amateur Radio. However on 6M the SWR and impedance is quite high. However this is most ideal situation. That’s not going to happen when the wire is hooked up as it will not have a 450ohm resistance.

Here is a video I made testing the EARCHI with the MiniVNA PRO

What about the counterpoise or the other half of the antenna?

If you look at the design, you will see that the “ground” is hooked up to the shield of the coax, so it would be suggested that you run some length of coax between the match box and your radio.

Testing the antenna in the real world

One could sit there and talk all day about using the antenna. Let’s see what it can do

I tested this right outside on my deck using a 31 foot fiberglass pole.  The wire is 30ft of #18 Poly-stealth.
The antenna only took around a minute or two to raise. I wasn’t really planning on making a video or even using the antenna that day so the batteries on the KX3 were not charged nor did I have it hooked up to an external source. I was using 3watts to conserve battery.

I went onto 15m and within minutes I managed to make a DX contact with LY10NATO which is a special event station in Lithuania. Not bad considering my conditions. The bands must have been in good shape. I then went to 20 and made contact with W1AW/4, an ARRL Centennial station in Tennessee.

I know it’s not proper to judge an antenna based solely on contacts but it just proves  that it works. If you need a QRP antenna that is portable and can get you on the air quickly then I would suggest the EARCHI to anyone. It’s easy to build and if you don’t have the time you can purchase one from EARCHI. It’s not a “Wonder Antenna” by any means but it’s hard to beat consider the cost and ease of use. Also having a decent match (tuner) helps.

Edit (4/3/2014): Someone on Youtube asked about SWR reading with the EARCHI. I decided to hook up the antenna to the KX3 with the internal ATU option using a couple configurations and here are the results. Please keep in mind the ATU in the KX3 has a wide ratio and could match a lot of wire. Doesn’t make the antenna any more efficient but it makes it work.

KX3 With KXAT3, EARCHI Antenna with around 30ft of #18 Poly Stealth and around 20ft’ RG 58 coax

Band Ratio
160m 18:1
75M 1.1:1
40M 1.0:1
20M 1.1:1
17m 1.1:1
15m 1.1:1
12m 1.2:1
10m 1.0:1
6m 1.0:1

KX3 With KXAT3, EARCHI Antenna with around 30ft of #18 Poly Stealth and around 1ft’ RG 58 coax

Band Ratio
160m 17:1
75M 4:1
40M 3:1
20M 1.1:1
17m 1.0:1
15m 1.0:1
12m 1.0:1
10m 1.0:1
6m 1.1:1

You’ll see that adding a length of Coax will help you out in the lower frequencies. Please note that results will vary depending on your equipment.

Let’s hook up the analyzer using the EARCHI w/ approx 30ft of #18 wire and approx 20ft of RG58 Coax

earchi20ftcoax

Thanks for reading!

 

Introductory look into the MiniVNA PRO.

As I get deeper and deeper into designing and building antennas, I figured I need something better than a SWR meter to make sure that my antennas are performing well. Since I am also publishing the antennas that I’ve designed and built here on this website, I would feel more comfortable knowing that it was done correctly. I needed some kind of antenna analyzer.

There are so many choices out there today that I was not sure what to get. The most popular antenna analyzer for amateur radio use is the MFJ-259B. You’ll see it or a model similar in a lot of shacks around the world.  I’ve used and enjoyed them but I felt that it was “Old School” considering technology has improved greatly. It was between the RigExpert AA-150 and the MiniVNA PRO. I purchased the MiniVNA as I felt it had more to offer. Being able to use Bluetooth to pair it up with an android device is what won me over. I found a used unit on QRZ for the price I was willing to pay. Wasn’t entirely sure about buying used  test equipment but it ended up working out for me in the end.

Mixed Reviews at First

The reviews for the MiniVNA and the MiniVNA PRO were mixed. A lot of people had a hard time getting it to work with their computer and a lot of people commented about poor documentation and how it was not “User Friendly”. Some claim to receive DOA Units. When it comes to reviews from hams (or anyone really), I don’t take them all for face value because I’ve seen people who are so called “Computer experts” fail to perform the simplest tasks like installing a driver. Instead of fixing possible problems with their computer/equipment, it’s easier to blame someone or something else. You also have those who have egos that are so big that anything they touch is the best because they only buy the best. Then you have those who give honest reviews that detail how good or bad the product is. It’s hard to know who’s reviews should be trusted.

First Impressions

Before the unit arrived at my house, I’ve read the 135 page manual about using the MiniVNA PRO and it’s software (vna/J ). I can see why people would think the manual is confusing. However I never used a VNA and I have no idea what any of the measurements mean other than SWR and impedance. I have a lot of learning to do so I can take full advantage of the VNA. Other reviews claim that the manual is NOT user (ham) friendly and geared toward experienced users but I feel that’s a challenge to learn more about the numbers I’ll be seeing. It will hopefully give me more insight into what’s happening with my antenna. I didn’t see much issue with the manual other than the order which topics were discussed.

Arrival

I’m lucky that the unit arrived right when I had some time to tear into it. Since it was used, I wanted to make sure it worked. It came with calibration slug/jumper cable and the seller even included a bluetooth module to hook up to almost any computer. Before even hooking it up to the computer, I went to FTDI’s website and made sure that I downloaded the latest drivers. Once installed onto my Windows 7 X64 OS, I hooked the VNA to the computer and the OS automatically recognized the VNA and  assigned it a com port. So far so good!

20140208_100753

Using  vna/J 

After downloading the latest vna/J (2.8.6f as of March 7th, 2015). I noticed it was a .jar file which tells me that it runs on the Java platform. Before running vna/J I made sure to update Java. Software started up with no issue and it was asking for a calibration file. First thing I did was go to the Analyzer menu > Setup. In the new window I highlighted the MiniVNA pro as well as the com port that is associated to the miniVNA. Once the proper unit/com port is selected, press the “Test” button. If successful, the status bar will turn green and  “Update” button will come active. After pressing “Update” the screen  will go away. You will still need to calibrate the unit.

First Calibration

Calibrating the VNA is easy if you ask me. All you would have to do is go to the Calibration menu and choose “create”. A box will pop up and if you have the calibration kit (SMA connectors), hook the “open” connector to the DUT port and press test. Then hookup short and then the 50ohm load. Once the calibration is done, save it and then press the Update. You are now ready to use the VNA. Whenever you load the vna/J software it will recall the last calibration file used. You can make different calibration files in case you’re adding adapters and cables you don’t want factored into the test. When you go into transmission mode, you will be asked to do a calibration using the jumper cable from DET to DUT. Similar to the reflection calibration.

Navigating around vna/J

I found it not to be confusing at all to use. The layout to me is simple and easy to use. Choose what you want to see (SWR / Reactance in my case), choose the frequency range by typing it in manualy or making a list, choosing reflection or transmission (reflection in the case) and pressing the “Single” button. I guess reading the manual helped but just messing around with stuff  helped me out even more. I ran a quick test leaving the 50ohm test plug on the DET port and the results produced a nice flat line at 50ohms and the SWR was 1.0:1

I’ve made a video showing the MiniVNA as well as installation and the first calibration.

First real test

Since I’m hot to trot, I grabbed whatever was nearby and tested it. It happened to be my Butternut HF9V located in my backyard. It’s 100ft away from my house fed with LMR 400. There is currently 7 radials in the ground.

u4agOxS

If the VNA is  correct, I need to go out and re-tune my antenna. From this plot I can see 75M has very narrow bandwidth (as mentioned by Bencher) and I’m off on a bunch of other bands.

20140311_182427

Tried re-tuning the antenna outside but it was so cold I decided it can wait for another day.

Bluetooth 

One of the main reason why I wanted this unit is because it’s truly wireless.  There is an application for the Android that allows the miniVNA to be used with a smartphone or tablet.
You could also use a laptop or desktop computer as long as it supports or could support bluetooth.

20140213_191537

 

I decided to try it wirelessly on a 10M dipole I had in my attic.
Screenshot_2014-02-13-19-23-08

If this is correct, then I need to shorten my antenna. It’s better than having too long instead of too short.

The application “BlueVNA” was developed by Dan, Y03GGX. For a free program it’s really nice.
I do have issues where the program force closes or stops working at random times on my Samsung Galaxy S3. It’s a minor annoyance but I can’t complain. reload the app and you’re back in business.
There is a claim that the miniVNA pro can transmit up to 100 meters which I would guess that would be under best conditions. Obstructions and quality of the other bluetooth module is a major factor. I’ve had it lose communications withing feet of the unit. I also tried it outside and worked well.

Measuring Transmission Loss

Someone gave me a low pass filter over and wanted to use the vna to measure it. An low pass filter allows “Low Frequencies” to pass through but attenuate or “block”

I was able to see how the filter reacts through a range of frequencies.

Here some other stuff I measured

Here is a video of it hooked up to a 1:1 current choke

eRsgZeV

The Diamond X510 on my roof. Not bad, it was as expected.

uIhPSqn

Rubber duck antenna that is on the TYT . I added a counterpoise to see what would happen as I feel that the chassis of the radio makes up the “other half” of the antenna.  Very very weird results.

Overall experience

After a few weeks of using the MiniVNA PRO, I’m quite impressed in what it can do for the small package it comes in. It was easy to setup (I think) and it was easy to use considering I never really used test equipment. Understanding what all the results mean is a different story but that means I have a lot more learning to do.  I’ve tested basically everything I can hook it up to.

If I were to get nit picky and they were going make a new version, I would ask for a metal enclosure, SMA connectors to be off the board and possibly an LCD screen with control buttons to make which would alllow to me to use the unit without the need for a computer or android device.

I think I made a wise purchase and I would recommend the MiniVNA to others that need something more than just looking at SWR

Thanks for reading!

SOTA Activation – Feb 22 2014 – Bare Mtn. (W1/CR-014)

Since it was a warm weekend than normal, I decided to take advantage of it and hike up Bare Mountain in Granby/Amherst area in Massachusetts and do a SOTA Activation.

20130423_172240

 

Elecraft KX3 Ready to go with Spare Batteries

Since this was a spur of moment thought, I didn’t have time to properly prepare my equipment. However usually when I come home from an activation, I take the time to repack my bag and make sure all the basics are included because I know I’ll be grabbing it with short notice. I could consider it my “Go-Kit” as it’s an entire HF station  with antenna that fits into a small backpack.

Need More Batteries

For this trip I didn’t even charge the battery from the last activation. Since I’m using a 3 cell (3S) 2200mAh RC/ battery with each cell being 3.7v, The battery pack will be fully charged at around 11.1v to around 12.6v. The KX3 Folds back TX power from 10w to 5W when the voltage dips below 11. This does not give me much room to play with. I am able to do an activation at 10W without much issue. If the TX power folds back, it’s usually at the end of my activation so my last contacts would be at true QRP levels. I could purchase a LiPo or LiFePo4 battery that has the proper voltage but that could end up costing me quite a bit of money compared to the cheaper RC batteries used in Quadcoptors and similar. The other option is purchase a 4 cell battery which could gives a 14.8 to 16.8v. It’s a little too much for the KX3 but you could step down the voltage using a couple diodes inline until the voltage drops below a certain point. The downside to that is the diodes will heat up. I’ll stick with the 3 cell for now but I should buy more and alternate them. At $10 a battery, you really can’t complain.

Before the Hike

Even though it’s short notice, there is some preparation that is needed before you leave. Besides making sure you have everything and double checking, it’s strongly suggested that you submit an activation notice (alert) to SOTAwatch.org. Even more so if you’re a CW operator. That way people will expect you. You wouldn’t want to spend all this time hiking and  setting up gear to make zero contacts. Since SOTA is gaining more popularity, it means there are more chasers and activators participating. There will always be someone listening out for you as long as you tell them when and where you’ll be. Cell/Data service at the summit is a huge advantage as you’re allowed to Self spot on the SOTA Cluster. CW ops have it even easier because if you send an alert through SOTAWatch, when you start calling CQ the skimmers will pickup your signal and automatically spot you on the SOTA Cluster. That’s pretty darn neat. I know people that have been involved with SOTA for a long time and they’ve told me stories of how they failed to make the minimum of 4 contacts. I have yet to have one of those activations and I hope it never will happen.

The Hike

The hike up wasn’t bad and the use of crampons helped since there were icy spots in the snow. After some huffing and puffing I made it to the summit with some time to spare.However all the time was used tring to untangle my mess of the mini G5RV that I use. It wasn’t designed for portable use and it uses #14 THHN wire. I took along tent stakes but ended up tying off the ends to near-by trees because the ground was frozen. I “Secured” the mast using bungie cord to a tree branch. It held up quite well

20140223_124834

 

Mini G5RV in a inverted V configuration. Mounted to a Jackite pole

Once everything was setup and checked, Out came the logbook and sent a spot over SOTAWatch.org. It didn’t take long for the traffic to come. There were times where I had pileups to work me which is real fun.

20140223_124831

 

Operating conditions. Notice the lack of seat.

The following operators worked me from the summit, if you worked me and  you either see your callsign wrong or not there, please contact me. I had a real hard time trying to write down calls correctly and It’s possible that I messed up your call. I try to check each contact against QRZ.com’s DB. It’s even better when the profile mentions SOTA as it makes me feel better the call is correct.

(20 METERS – Start 16:34Z)

  • N4EX
  • W0MNA
  • K1MAZ  (SOTA Jerks)
  • G4OBK
  • W7RV
  • W5ODS
  • KU4GC
  • K5WI
  • KD8NBB
  • DJ5AV
  • AA7DK
  • NS7P
  • WA2USA/4 (In Florida)
  • N7AMA
  • KB9VZU
  • EA7HX
  • G4UXH
  • G0VWP
  • G0RQL
  • G6TUH
  • K8SSS
  • KK1W (SOTA Jerk)
  • KAEZE
  • AK4BH/QRP
  • KC9TTR
  • W5RST

(12 Meters – Start 16:55)

  • W5RST
  • AD5A
  • KK1W
  • W0KEU

(15 Meters – Start 17:03)

  • G6TUH
  • M0MDA
  • EA2DT
  • M6ARE ??
  • G4UXH

(40 Meters – Start 17:13)

  • KB1RJC
  • KB1RJD
  • VE3JCW
  • N2ICE ??
  • N7UN
  • KK1W

(10 Meters – Start 17:30)

  • W7RV
  • G6TUH

(Contacts with other SOTA Summits)

  • W7IMC (W7I/SR-138 Idaho)
  • KI4SVM (W4C/WM-039) (NC QSO Party)

Over 45 contacts were made, I also chased some DX I heard while scanning around the bands and chasing other SOTA activations. I’m glad to make a  couple Summit to Summit contacts which to me is more thrilling as we’re both on summits with less than ideal operating conditions.

20140223_124809

There were a lot of other hikers up at the summit and some came over to talk and were amazed that I was contacting Spain and England considering what I had.

20140223_131126

 

View  from the other side of the Summit. You can see UMASS, Amherst and Hampshire college from this view

I could have stayed longer but Kneeling in the snow wasn’t helping me out. I need to find an easier way to be more comfortable during the winter activations. Thinking about using a kneeboard that I can attach my radio to that also has a clock. The hike down was a lot harder than the hike up. I kept sliding and had to use my antenna mast as a walking stick at times.

20140223_132139

Notice someone made little snowmen along the trail

Lessons Learned

Besides having extra batteries, I think some kind of seat or something that would allow me operate more comfortable. I was either standing  or kneeling down in the snow which was more damaging to me than the hike. It was extremely difficult to log contacts while holding the microphone.

Thanks for reading!

 

SOTA Activation – Jan 18th – Mt Tom (W1/MB-006)

It’s a new year! For those who are into activating summits, this means we can go back out and activate our easy and close-by summits that will count for points.  A known SOTA activator in the region (Doug, W1DMH) was going to be in the area activating a couple summits which caught the interest of a couple other hams in the area..  It was reported that it was going to be a rain/sleet/snow mix for the entire day so I was under the impression that I wasn’t going to be out. While out running errands, I’ve noticed it was clear enough so I ran home, got my gear and went to Mt. Tom.

It’s been awhile since I activated any kind of summit. I would also say it  was the last time I really ever “exercised”. The hike up was not easy. I had to stop a few times to catch my breath and I ended up taking baby steps to  the summit.

SOTA 1/18/14 - Mt Tom

Once I got to the top of the mountain, I was able to catch my breath but then I had to setup shop. Visibility at the summit was poor due to weather. Due to other activators in the area were already on the air, I had no time to walk around to see what was up.

Setting Up

After seeing a lot of activators using some sort of monopole to support their antenna, I jumped on  the band wagon and purchased a fiberglass kite pole during the holidays

Jack Kite Pole

I ended up going with the 31′ Jack Kite Pole.  I wouldn’t say that it’s the best choice for activities like SOTA. Soon as I got it out of the box, the threaded cap came off. It happened more than once which caused all the sections to fall out. I’ve also read reports of the top sections breaking under light loads. To be fair, it was designed to be use with kites. To combat the issues, I’ve removed the top two sections and made a sheath using left over outdoor canvas that I used for my Elk antenna. The sheath has a shoulder strap that allowed me to carry the pole w/o much issue.

20140118_123533

 

Here is the kite pole with antenna mounted to the top.

In past activations that included the same exact spot, I’ve used a Mini G5RV by throwing rocks with a rope attached into the trees. The trees on some of these summits are not that tall and could only manage to get the antenna 6ft off the ground. It worked but I could have done better if it were higher. This time with the kite pole, things went much faster even though I had some issues  with getting the wire  snagged  in nearby tree branches.

20140118_123822

I try to stay as minimal as possible. Even more so if  know the layout of the mountain/hill. What you see in the above photo is what I took up. I packed the KX3, microphone, battery, 90 degree BNC adapter, antenna, kitepole, mason line (rope), elastic cord, tape and 2m HT. Due to the massive amount of RF that is already present on top of the mountain, doing a VHF activation is out of the question. I’ve heard other people up there trying to do VHF and they always had trouble receiving.

Getting On The Air

Once the antenna is up, getting on the air is quite easy. However getting spotted or spotting yourself (which is allowed using SOTAwatch) could be difficult depending on conditions and which mode you’re using. I lucked out because I had cell service and was able to spot myself. Since this was last second, I didn’t have the time to give advanced warning of the activation.

20140118_131908

A minute or so after spotting, my first call was from Doug (W1DMH) who was on another summit nearby. This counts as a Summit to Summit (S2S) contact that gives both doug and myself extra points. I was hoping to work Jim (KK1W) and Frandy (N1FJ as NE1SJ) that were also on nearby summits but I sort of arrived late to the game and missed out on 2 additional S2S.

After the first contact, the rest came in one after another with the occasional pileup. It was very exciting and made it worth the trip up. Talking on SSB with stations all around the US is fun when you’re using low power. I can see why people find QRP to be very rewarding. I also made some DX contacts with stations in Canada, England and my furthest contact with GI4OUL in N. Ireland. Approx 3000mi only using 7W (428mi per watt)  is not bad.

Thanks to the following who worked me.

Call Time Band Mode Notes
W1DMH 17:43 14MHz SSB Thanks For S2S
N4EX 17:44 14MHz SSB Thanks!
AE4FZ 17:44 14MHz SSB
VE1WT 17:45 14MHz SSB
AJ5C 17:45 14MHz SSB Thanks!
K0LAF 17:45 14MHz SSB
W0MNA 17:45 14MHz SSB
WG8Y 17:46 14MHz SSB
NS7P 17:46 14MHz SSB
KI4SUM 17:47 14MHz SSB
W7RV 17:48 14MHz SSB
W4DOW 17:48 14MHz SSB
NE4TN 17:49 14MHz SSB
WA4WKL 17:49 14MHz SSB
W4SKC 17:50 14MHz SSB
VA6FUN 17:52 14MHz SSB 2000mi on 10W TY!
AD5A 17:52 14MHz SSB Thanks for TX!
W5ODS 17:52 14MHz SSB
K4WAI 17:53 14MHz SSB
G4UXH 17:54 14MHz SSB Thanks for DX!
N6KZ 17:55 14MHz SSB
AA7DK 17:56 14MHz SSB
WB9EAO 17:57 14MHz SSB
K9ICP 17:58 14MHz SSB
GI4ONL 18:00 14MHz SSB Thanks for DX!
KC4TAC 18:00 14MHz SSB
W7RV 18:14 24MHz SSB
W1MSW 18:15 24MHz SSB

After doing a few summits, some of the callsigns start to become familiar as they chased me on other summits in the past. It’s nice to hear them and it makes it real easy to pick them out on packed/noisy bands.

Lessons Learned

Even though I’ve done over 6 summits alone, I’m still learning things along the way. For example, my logbook.

scratchlogsota

 

It’s an envelope… Not an logbook. It works but not well. I need some better way to log contacts w/o using some big and bulky notepad.
The G5RV needs to replaced with a SOTA version. Right now the current G5RV is using #14 electrical wire and the ladder line is solid core. It’s bulky and tangles to easily.  I would like to still use the G5RV as it works well but I would like to use polystealth wire and a ladder line made from stranded cable that was thinner.

Thanks for reading!

Antenna Reviews: Arrow Satellite II Vs. Elk Log Periodic

I was given two popular antennas to use for a decent amount of time. I figured to try them both out and share my feelings about each one. I was given the Arrow Satellite II from Arrow antennas and a dual band Log Periodic from Elk Antennas. We’ll look at each antenna individually and then compare them to each other.

Arrow Satellite II

Whenever someone mentions working amateur radio satellites (reapeaters in the sky), the Arrow Satellite II is almost always mentioned. It’s been mentioned so many times that I wanted one.  However like most hams, I’m cheap! If I feel that I can make the exact same antenna, I will try my best to do so. I tried looking for the plans for that antenna but couldn’t find them. I was bummed out until someone I knew (N1KXR) purchased a used one from another ham. This was the perfect time to  take the antenna and dissect it.

The first thing I did when I got the antenna was to assemble it and PLAY!  The actual assembly of the antenna was OK. The reason it’s called an ARROW antenna is because the elements are made from aluminum arrow shafts  that are used in archery. The great thing about using arrows is  that they are light and built to some strict specs.

I like that it’s light weight and that I can setup the antenna to either VHF or UHF or Both. The duplexer inside the handle is a big plus.  I don’t have a spectrum/network analyzer or lab equipment to give you the in-depth specs of the antenna (I just wish I knew) but it shows good SWR on  my bridge (meter) and it performs. The only thing I would do if this was mine is to use different color electrical tape (or paint markers) to identify the correct pairs of elements. I lined them up by height. I would also drill a hole in the handle (away from the duplexer) so I could mount  the antenna to a tripod better. As I found with the PVC Tape measure yagi, It gets heavy after holding it for awhile.

Let’s Reverse It!

I wanted to make this antenna almost exactly the same way it was purchased. From using arrows shafts all the way down to the micro-duplexer that is in the handle.  I didn’t want to drift far away from the original design so out came the 5ft vernier calipers and went to town remaking the entire antenna in CAD.

Arrow Yagi 3D Model

After putting all the dimensions back into CAD this is what I got. I would like to say it’s within .005″ and the antenna is possible to reproduce if you have access to a drill press, arbor press (can’t tell if the BNCs are pressed) and lathe (Or a good fixture for the drill press) as most of the work would be focused on the driven element/gamma match.

Is it worth making your own?

Even though I have access to some of the material, I wanted to look at as if I had nothing and had to go out and buy all the material. So I started calling around for quotes on material. The more and more I got into it, the price kept climbing and climbing.

Let’s start off with the Arrows. I wanted to use the same aluminum arrows just like the ones that are used on this antenna.  I went looking for the Arrows they used based on the dimensions I got from reverse engineering. While trying to find these arrows I learned a lot about all the different types of arrows used in archery.  When it comes to aluminum arrows, they use a 4 digit number system. The first two digits are the diameter of the shaft in 1/64″ increments and the last two digits are the wall thickness in 1/1000″.  I found out that they are using  1716 arrow and the only ones I can find are by Easton (Easton Blues/Jazz) and they are not cheap. Just the shafts would end up being $60-$70. That doesn’t include the 8-32 Inserts.

The tubing, square stock and bar stock for the boom and gamma match would add up to approx $30.

BNC connectors, Coax, plastic tubing, wire, screws and threaded rod would add up to approx $20.

So far we’re looking at least $100-$120 for the material and that doesn’t even include the micro duplexer. You can purchase the duplexer ready to go from Arrow Antennas for around $60 or you can make it yourself using the plans found on KI0AG’s Site that appears Arrow Antennas used as well.  If you don’t have the means or equipment to make/etch your own boards then it will still cost a decent amount of money.

For me, It’s not worth building.

The price of material would meet or exceed the cost of the antenna if you were to buy it from Arrow. This doesn’t include the splitboom, duplexer and labor involved. As much pride as I take in building my own, it’s not worth it. I can buy the antenna already made for less then it would take to manufacture. I tried things like using 1/4″ solid aluminum rod to reduce the materials costs but now you are spending more time in labor in drilling and tapping for a 8-32 screw. A lathe would really help in this situation.

How does it perform?

I can’t get too technical because I don’t have any of the testing gear or the know how to give you exact figures.  The following evaluation is just from my personal observations.

The way I received the antenna was in a tube with what appears to be the original plastic bag that separates the UHF and VHF Elements. Since this antenna is used, I am not sure how it comes from the factory. Assembling the Antenna is quite a challenge. The elements are NOT labeled! What I had to do was line up the elements by height and pair them together for both the VHF and UHF side of the beam. For me, most of the time assembling this antenna is spent finding out which element is which. This would be my only complaint about the antenna. However it can be fixed by doing a couple things. Buying multicolored electrical tape and put some tape on the elements and boom. You can also purchase or make your “Antenna” bag with pockets for each pair of elements.

Assembly is pretty much straight forward once you know what goes where, Just screw them together through the boom, hook up the BNC connector and you’re  ready to go. I’d suggest the first time you put it together to check SWR and adjust the gamma match for optimal SWR.

I spent some time tracking Sats, hitting repeaters that I can’t normally hit with a rubber duck and some back yard RDF. The antenna performs, I was able to pickup some satellites like the NOAA and some Ham Sats and it performs just like you would expect. There is nothing much more I can say performance wise other than it works.

Pros:

  • Uses aluminum
  • Lightweight
  • Tuneable (Gamma Match)
  • Built in duplexor
  • Use either 144 or 440 or both.
  • Breaks down into a small area

Cons:

  • Elements not marked
  • Arrows can break
  • Built in duplexor
  • Very bulky when assembled
  • Hard to transport

If you noticed I put duplexor in both the pros and cons. The reason is because it’s great that you just one connection to the radio but you will have loss at the duplexor. I would assume the loss isn’t much at all so I wouldn’t be to concerned.

When you assemble both the VHF and UHF side of the beam, it turns into quite a bulky object and would be harder to transport inside your car. Not saying it’s impossible but you would most likely have to break down one band of the antenna.

Overall a great antenna and would recommend it to anyone that is serious about portable sat work, RDF and low power operations (<10W)

Elk Log Periodic 

Whenever the Arrow antenna is mentioned, the Log Periodic by Elk Antennas is also mentioned and vice verse. The antenna is known as a log periodic which is a little bit similar to a Yagi.  Instead of one boom, It uses two booms which the elements that are attached to each boom are 180 degrees from the elements on the other boom. In a simple way I can put it is that it’s a bunch of dipoles of different lengths. When the signal enters the antenna, it will find the best pair of “Dipoles” for that frequency and the other pairs help direct the signal.

Lets reverse it!

Well I didn’t. I didn’t think it was worth it.

The antenna is made with some quality parts. The Booms are thick walled aluminum tubing. They are spaced part using plastic spacers and plastic bolts and it has tapped holes along the boom with #10 screws to hold the elements.  The boom is mounted/supported by two different grades of PVC tubing. The PVC used for mounting is schedual 40 and the other appears to be electrical conduit.  The elements are also aluminum tubing that appears to have been either wet or powder coated with vinyl caps to protect the ends. They also have pressed in threads (10-32). They are high end tent poles. Included is a Handle made from PVC tubing that has a foam grip fitted to one side. This handle allows for portable ops.

Is it worth making your own? 

I priced everything out as if you didn’t have any of this material laying around the house and you started from scratch.

  • 4Ft Aluminum tubing for the boom – $25
  • 12ft Aluminum tubing for the elements – $35
  • PVC for mounting – $10
  • Vinyl caps – $5
  • Stainless Screws/Nuts (Nylock) – $15
  • Plastic Screws/spacers – $10
  • SO-239 Chassis mount – $5

Total Materials cost – Approx $105

Just based on materials alone, It’s cheaper than if you were to purchase one.

For Me, It’s not worth building

Even though the materials are cheaper than what it’s being sold for, there is quite a bit of work that has to go into this antenna. One of the booms will have to be machined for a notch to allow the SO-239 connector to sit flush. There is also a LOT of drilling and tapping going on. That means you need a drillpress that is almost perfectly 90 degrees and fixtures/jigs available to drill nicely through round stock. If you don’t have the time or you highly value your time, I can see 4 or so hours in manufacturing and assembly. If you wanted to go all out and powder/wet paint the elements, then you are add more time and costs.

How does it perform? 

Once again, I don’t have the equipment to give you a proper assessment of the antenna. The following evaluation is just from my personal observations.

I got the antenna mostly un-assembled in a bag.  I am not sure how it comes from the factory as this is also a used antenna. Assembly is easy with this antenna. The elements and boom are marked with different colors. All you have to do is match up the colors and screw them to the booms (Yep, still calling it that), connect the coax and away you go!

I was able to receive some Sats, and hit some distant repeaters with my HT. I also mounted this to my simple TV rotor in my attic and used it with my FT-1900R.

20130220_201947

 

I even did a night time SOTA activation with it. Worked quite well.

Pros:

  • Easy to assemble
  • East to transport when assembled
  • Dual band
  • No duplexor
  • Easy to break down
  • Can be semi permanent install
  • Can accept up to 200w VHF and 100W UHF

Cons:

  • Uses PVC 
  • Coax has to be positioned correctly to avoid SWR issues

Even though the antenna works and does a great job, The use of PVC just makes me feel that the build quality is… meh. It has a home-brew feel to it, that’s all. When hooking up the coax, you have to keep at least 8″ of the coax 90 degrees from the boom as suggested on their website. In order to get the most out of this antenna, you would have to make some sort of fixture to mount the coax correctly which could be a hassle depending on how you’re looking at it.

 

Dueling Antennas.

Cue the banjos and setup the octagon because we have a fight on our hands. Well… Not really. There is no winner and there is nothing that would make one WAY BETTER than the other. They both have their unique features and they both pretty much perform equally in my book. I like the Elk because it’s not as bulky and can handle more power but I like the Arrow because it doesn’t use Plumbers\Electrical PVC and it’s easy to adjust. If push came to shove and I had to make a choice, I would lean toward the Elk. If they redesigned the boom holder/mount using something other than PVC tubing then I would prefer the Elk over the Arrow.

20130307_170603

I decided to make a carrying case for the elk. I used outdoor canvas and my sewing skills are absolutely horrible. But it’s better than the nylon tent bag that was being ripped up by the screws that are sticking out of the boom.  Now all the elements are organized and I have a pocket to put coax or a small handheld radio. The green tube in the background is what holds the arrow that was created by the owner of the Arrow.  It appears to be a pool stick bag with a PVC pipe. It’s long because at the time, it was one solid length of boom

20130307_171039

 

Here is a photo of both the antennas un-assembled.  At the point of taking this photo, the Arrow still has a one piece boom. They both pretty much take up the space if the boom was split on the arrow.

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Here is the duplexor that is located within the handle of the Arrow. Wasn’t going to cut the shrink wrap to show the circuit but it’s no secret. the plans are out on the internet.

20130307_172104

 

Here are both antennas assembled. You can see that the Arrow is bulkier due to it’s cross polarization and it’s a bit longer than the Elk. But I will say that the arrow “Feels” lighter. I wouldn’t be holding either antenna for an extended amount of time.

20130308_131328

Here is the “Split Boom” modification I did to the arrow antenna. This is available as an option from Arrow Antennas and I would suggest spending the extra money to have it done for you. What’s great is even though arrow sells a split boom model, they published the modification to make your one piece boom into a split. I followed the directions on the site except for the angle. I used a piece of 1/2″ plumbing copper pipe. I should have turned it down in the lathe as it was a really tight fit. Once I got the copper pipe a couple inches in the boom, I drilled a hole through the boom and tube and used aluminum pop rivets to secure the copper tube. Once I got the other end of the boom to slide on the copper pipe and meet the angle, I drilled a hole through copper tube using the hole for the first director element for the UHF side of the antenna. This way when you thread the arrows through the boom and tube, it will “Lock” the booms together. Nice move on arrows part.

Overall there is no clear winner. They both have their strengths and weeknesses. My personal preferance would be the elk even though I wouldn’t mind the arrow at all. Tasters choice I guess.

Thanks for reading!

73,
NT1K

My Offset Attenuator Project

Even though I have yet to participate in any type of Radio Direction Finding (RDF) event, I find myself buying and building stuff for it.  This time I decided to build an offset (active) attenuator as I think it’s a must need for RDF. When I was testing out my 3EL tape measure Yagi, I placed a transmitter on my property and tried to find it with a Yagi and found that it was near impossible to pinpoint the source as my radio was showing full scale and dead full quieting no matter where I went.

Since I’ve been reading a lot about fox hunting, I knew I needed an attenuator. However there are different kinds of attenuators that you can make or buy commercially. I wasn’t sure what to get at the time. I narrowed it down to the offset attenuator and the  step attenuator. I went  with the offset attenuator because it appears to be cheaper, easy to make and better than a step attenuator.

The attenuator that I went with was found on HomingIn.com’s  Website. The article was writen by Joel Moell (K0OV) and explained in detail about the attenuator. What the offset attenuator does is “Offset” the received signal by 4MHz using a diode, oscillator and some other passive components. You are now listening to the signal away from it’s transmitting frequency. Your antenna and radio is no longer being overloaded and you’ll be able to get even closer to the signal.

It appears to be quite easy to build, even for me!  So I went with it. The parts that are listen in the article are a little outdated

Here is an updated list of parts that I purchased. I usually use Mouser for components but I wasn’t satisfied with their shipping to the North East so I used Digi-Key with better results

Qty Desc Price P/N Source
1X CAP CER 470PF 2KV 10% RADIAL $0.23 ea 1286PH-ND Digi-Key
2X CAP CER 4700PF 50V 10% RADIAL $0.30 ea BC2683CT-ND Digi-Key
2X RES 2.2K OHM 1/4W 5% CARBON FILM $0.10 ea 2.2KQBK-ND Digi-Key
1X RES 4.7K OHM 1/4W 5% CARBON FILM $0.10 ea 4.7KQBK-ND Digi-Key
1X DIODE SMALL SIG 100V 200MA DO35 $0.10 ea 1N4148TACT-ND Digi-Key
1X OSC 4.0000 MHZ FULL SIZE $2.49 ea CTX774-ND Digi-Key
1X BNC FRONT MT RECEPT SHORT $4.67 ea ARF1064-ND Digi-Key
1X 5K Audio Tape Pot $3.49 ea #271-1720 Radio Shack/In-Store
1X Perf Board/PC-Board $2.49 ea Radio Shack / Instore
1X SPST Swith $2.49 ea Radio Shack / Instore

Total project cost:  Approx $8.00-$18 USD

Making Sure Everything Works

Before putting it on any type of board I wanted to make sure that It works. I never really messed around with making electronic devices from a pile of parts. I put the entire project onto a breadboard  following the schematic as close as possible

20130209_201941

 

Here it is being tested out on the breadboard It went together pretty easy. I used a voltage meter to make sure the correct voltage is coming out of the LM7805 regulator. I was seeing around 5V

Here is a video of it in action

Now that I know it  works, it’s time to transfer the design to a more permanent home. I wanted to compact it as short as possible to get it to fit into a small PVC box.  Since I had a PVC box I wanted the board to go into, I measured a piece of perf board and cut it up

After cutting the board, I laid out all the components and attached all the wiring I could from underneath the board

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Here its with most of the stuff attached.

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Here is the Top view of the board. I had to use some jumpers (red and green wires) to get some of the components to make contact.
The black wires you see leading away from the board are for power and the adjustable resistor. I tried to test it out at this point to make sure it works before adding the coax and other things but It turned out not to be worth doing. But I did check the circuit wiring a couple times  to make sure.

Final Assembly

Getting it jammed into the small box was going to be difficult. I knew right away that I wouldn’t be able to fit the 9V  battery and the circuit board into the same compartment without using a larger box.

20130305_211224

 

Here is the PVC junction box with the circuit board, switch, POT and cabled jammed into it. I had to have shave some of the flange off  on the cover as the Pot is almost the same size as the Inside dimension of the box.

20130305_211053

 

To solve the battery issue, I fabricated a small aluminum box that can hold a 9V battery. I drilled a small hole in the side of the PVC case to route the power cable through. In the above picture you can also see the on/off switch and adjustable pot. I mounted the switch sideways to avoid any accidental switching even though it’s still possible.

20130305_211040

 

Here is the fully assembled antenna. The PVC junction box is also used to mount the grip handle. This way most of the weight is sitting on top of my hand instead of  out on the boom. I also didn’t want to put any kind of electronics/metal between the reflector and driven element. Not sure if it would make a difference but I think it’s better off this way

Lessons Learned

I learned a lot while making this attenuator.  The circuit was simple enough to where I can understand what is going on.

If I were to build another one, I would make some changes to make it even better.  The big problem is that the coax runs from the driven element straight into the attenuator from inside the PVC. This doesn’t allow me to swap out antennas. What I would do is put a BNC connector sticking out of the PVC box and have the coax come out the boom to make the connection.  I could  just make an attenuator that is seperate from the antenna but that is just another bulky piece of equipment to carry around. I wouldn’t want to attach it directly to the radio because I think it would put strain on the  connector that is in the radio.

You also can’t TX using this antenna. If you do, you can kiss the diode and possibly other parts goodbye. I would try to install some kind of switch that would allow me to TX but I’ll just carry an extra antenna or extra radio for now.

Hopefully it will see a lot of use.

Thanks for reading!

73,
Jeffrey Bail (NT1K)

 

Homebrew 5 Element VHF Yagi

 

Okay, enough of UHF/GMRS antennas. Now it’s time to step it up (just a little bit) and fabricate a bigger antenna.
Due to material, I decided on a 5 element Yagi built for VHF since all I would have to buy is more 3/8″ round stock. I’ve taken what I learned from the GMRS Yagi and applying it to the design and fabrication of this VHF Antenna. I am writing this article in a way in which I hope newer hams can understand, build and learn about antennas. So please excuse if I go into details about things that you consider simple and  “common sense”.

In order to design a Yagi we have to learn what a Yagi is.  A Yagi is a Directional antenna made of up elements.


The 3 Major parts which make a yagi are the driven element, reflector and director.  When cut and placed at a calculated distance (On a Boom), the elements will cause the RF (Power) to be sent (radiated) or received in whichever direction the antenna is pointing to. In the radio world this is a great because you can basically “Focus” the power and direct it in the direction you want. Whereas a Vertical (Omni-Directional)  radiates its energy in a 360 degree pattern (think of throwing a rock in a still lake and watch the ripple pattern in the water.) which will send out your signal “everywhere” but will dissipate quicker.

On the lower frequencies (HF), a Yagi would be the antenna of choice by Hams. Well then how come every ham doesn’t have a Yagi (on HF)? There is a couple of down sides to having a Yagi or Beam antenna (on HF). First off, HF Yagis are huge. In order to use a Yagi/Beam to it’s fullest you would have to install an antenna tower/mast and rotor. HF Yagis are expensive and so is the tower and rotor, so the parts alone could add up to couple thousand dollars. I’ve seen cases where someone moved or is SK (Passed on) and sold their equipment cheap.  There are also several other factors that would steer someone away from a Yagi. Those factors could be age, housing restrictions, living in an apartment, permits, handicap, property size, neighbors, and more stuff than I list. However the Yagi I’m building does not take much space and could be transported to be used in events where I am portable. Yagi’s come in many different sizes depending on the frequency and the efficiency of the antenna. The lower the frequency, the larger the antenna. The higher the frequency, the smaller at antenna. The length of the antenna will vary depending on how much efficiency/gain you want. Increasing the length (boom) and adding more director elements will increase the gain/efficiency of the antenna. On the Yagi that I am building, the design is based on the length of the (boom) antenna rather than the gain.

So you want to build a Yagi. To start off your going to have to know what material your going to be using. Most Yagi antennas are built using Aluminum since it’s light and is a great conductor (Well, compared to steel/stainless). There are many different types of aluminum and I would say that 6061-T6 Aluminum would be the best choice for antenna building.  The reason is that 6061-T6 is more weather durable and easier to work with compared to other aluminums. The downside of 6061-T6 is when it comes to bending. 6061-T6 tends to crack when bending using a tight radius. Since we’re not bending anything on the yagi we’re building then It won’t matter. If it comes to other designs of yagis that use a Hairpin or folded dipole then I would take the type of aluminum into consideration.

Okay, we’re using Aluminum. What’s next? Now we need to figure the sizes of the material we’re going to use. This all depends on personal preference. For HF Yagis, you’re going to need Tubing ranging from 2″,  telescoping in diameter down to 1/2″  because the antenna is going to be big and will need to support the weight of the elements. Since we’re dealing with smaller VHF/UHF antennas, the material doesn’t have to be large. For the antenna that we’re building we will be using 3/8″ (.375″/9.5mm) round solid aluminum and 1″ (1.00″/25.4mm) square tubing to mount the elements to. You can also use 1/4″ solid round aluminum instead of the 3/8″ to save a couple of dollars but realize that it’s easier to damage 1/4″ rod. If you decide to go with 1/4″  round please note that the dimensions and calculations you see in this article will NOT work using 1/4″ rod because 3/8″ rod has more surface area for the signal to travel on and all the calculations are made with 3/8″ In mind. You can change it to work with 1/4″ which I will cover later on.

Now that we have the material and size in mind that we’ll need, we now need to know what frequency we want to transmit on. Since this is a VHF yagi that we’re building, it will most likely be in the 144-148 range. Are you going to use this antenna for sideband (ssb/usb) only, or both ssb and FM (repeater/general operation)? Reason I ask that is if your designing this to be on sideband only, you will only need it to design it to work best over the span from 144.000Mhz to 144.500Mhz whereas FM would need to be designed over the entire band (144.000mMhz to 148.000Mhz). Since we’re building an antenna for the entire 2m band, we going to use 146.000Mhz as the design frequency  since it’s directly center of the band and would allow for a somewhat even performance throughout out the band.

Another downfall of the Yagi is that it has a narrow bandwidth.What I mean is that the antenna will work the best over the span anywhere from  100khz to 10mhz depending on the design (Could be more or less).  If you start transmitting out of that span, it could create signal loss and high SWR causing the transmitter to step down power to prevent damage (or actually damage older radios). Why build an antenna that is not going to radiate the power going to it?  If the antenna is designed and fabricated correctly and you have at least a SWR Meter/Bridge then this should not be an issue.

So now we have everything we need to start designing a Yagi-Udi Antenna. Well… How do you design one? This is a fork in the road and there are many different ways you could design one (too many to list). There are different programs for different types of Yagis and there are different mathematical formulas for different (or the same) types of yagis.  The method I am going to use is a Antenna modeling  (software) program called 4NEC2.  This program is based off the Numerical Electromagnetics Code for modeling antennas. The great thing about 4NEC2 is that you can model almost any antenna and the best part is that its FREE!  What this software allows you to do is to design/draw an antenna using X,Y,Z Coordinates and then run the antenna through a simulator to see it’s efficiency, SWR, impedance and many other things that I have yet to look at. Basically it will tell you if your antenna is going to work and how well it will work on or near the frequency you designed it for. Another great thing about 4NEC2 is that it will perform adjustments on your antenna to optimize it for the best results. So if you are somewhat close to a good antenna, the software (if the programed right) will make it even closer. This software however is slightly (or very) difficult to use for a new person in the hobby. I adapted to the design portion of the software because I have knowledge in CAD (Computer Aided Drafting), but I had to do a lot of reading about the electrical properties and how to make the software do what I want. I am not going to dive in depth explaining this software. However, I will show you how I used the software to create the antenna. If you find the software to difficult then skip the section and use the final results in building your antenna.

Before we start using the software, we’re going to need to know what dimensions to input in the software. We can’t just throw random numbers into the software and expect magic to occur and produce the “Perfect” Yagi antenna. The U.S Department of Commerce and the National Bureau Of Standards released a document which helps in Yagi Design. Information based off the manual has lead to the following Dimensions

300 (speed of light in meters)/146.000(mhz) = 2.0547 wavelength or(WL) (in meters). This will be used as reference for the following dimensions.

Length of each element as follows:
Reflector Length = 0.493 X WL=1.01297m (or 39.880″)
Driven Element Length = 0.473 X WL = 0.971873m (or 38.262″)
Director 1 length = 0.440  X WL = 0.904068m (or 35.593″)
Director 2 length = 0.435 X WL = 0.893795m (or 35.188″)
Director 3 length = 0.430 X WL = 0.883521 (or 34.7843″)

Spacing of each elements from the reflector as follows (WL = 2.0547 in meters)

Reflector to Driven element = 0.125 X WL = .256838m (or 10.1117″)
Reflector to Director 1 = 0.250 X WL = .513675m (or 20.223″)
Reflector to Director 2 = 0.500 X WL = 1.02735m (or 40.446″)
Reflector to Director 3 = 0.750 X WL = 1.54103m (or 60.670″)

Now that we have all the dimensions that will put our Yagi in the “Ball Park” of a good VHF Antenna. The software will end up fine tuning the elements and spacing between elements to obtain the best SWR for the giving variables (i.e Element diameter, Boom length and etc).

Open the 4NEC2 and plot the antenna using the dimensions above. At some point in the near future, I will post a video on how I plotted the antenna. If you don’t know how to use 4NEC2 I suggest searching using google for results because that’s how I learned.

Please note that using the “Optimization” will give different results what I came up with. So do not get alarmed or worried. If it was done right then there shouldn’t be any issues to the design that the software gave you. DO NOT START CUTTING ANYTHING!! These dimensions will change!

Here are the Dimensions and spacings from 4NEC2 that I got! (Note that these dimensions will be the ones used for the rest of the article and that they will be different than your results if you decided to use the software)

Spacings (Each from the reflector)
S1 =12.469″
S2 =20.492″
S3 =37.933″
S4 =58.000″

Element lengths
RL =40.495″
DE =38.363″
D1 =36.056″
D2 =36.086″
D3 =34.074″

Now you should have all the Dimensions (lengths) of the elements and the spacing. Now we need to work on the BOOM. The Boom is the tube that we are going to mount the elements on. At this point we have to decide what material, size and length we’re going to use for the boom and how we’re going to mount the elements. I have decided on 1.000″ square aluminum tubing because it’s commonly used and that it’s easier to work with compared to round tubing. The length that we’re going to need is based on the location of your last (furthest away) director.

I also decided to mount the elements by drilling through the boom and using plastic shoulder washers so we can slide the elements through the boom without the elements contacting the boom. At any point we DO NOT WANT THE ELEMENTS TO CONTACT THE BOOM!! Because we’re putting the elements through the boom, the elements will become electrically shorter because of the inductance change. So we would have to increase each element which is called “Boom Correction”.

There is a formula to calculate the “Boom Correction”. In fact, there are many different formulas to calculate the correction so I am going to use the one that I see most on the internet

C= (12.597B) – (114.5B^2)
The C equals the correction, and B equals boom diameter in wavelengths. This formula will work on boom diameters smaller than .055 wavelengths (Smaller than 4-1/2″ boom diameter on VHF and smaller than 1.5″  boom diameter on UHF). So let’s dissect this problem to make it easier.

To find B we’re going to need the wavelength of the frequency (146Mhz) that were going to use in millimeters.
300/146 = 2.0547 meters or 2054.7 millimeters.

Now we need to take the boom diameter in mm (1.0″ = 25.4mm) and divide it by the wavelength (in MM) of 146Mhz
25.4/2054.7 =0 .012362 (B is .012362)

Now we can do the problem
(12.597*0.012362)-(114.5-(0.012362*0.012362))=.138226

Now we take the correction and multiply it by the boom diameter (in MM)
.138226X25.4 = 3.510mm or .138″ is out correction

We now have to ADD .138″ to EACH element.  So our NEW element lengths (in inches) are as follows.

RL = 40.633″
DE = 38.501″
D1 = 36.301″
D2 = 36.224″
D3 = 34.212″

At this point we should have all the lengths of the elements, spacing distances from the reflector to each element, boom diameter, boom length and the type of material we’re going to need for fabrication… Right?

We need to go shopping before we build. Here is a list of what we need to build

  • 5ft (60″) of 1X1″ Sq Aluminum tubing (1/16″ Wall/Thick)
  • 16ft (192″) of 3/8″ Round Aluminum Rod

I would suggest that you google for a local “metal supply” shop. I would avoid the big chain stores (like Home Depot, Lowes) or stores that have every type building material under one roof because the markup on material is very high. I was able to purchase 12ft of sq tubing and 24ft (2 12ft lengths) of rod for around US $30. There was enough material to build this antenna and two UHF 3 Element beams.

  • 8pcs – 3/8″ Inside Diameter Plastic Shoulder Washer
  • 6pcs – 3/16″ Inside Diameter Plastic Shoulder Washer
  • 1pcs – 3/8″ Inside Diameter X 3/4″ Diameter X 1-1/2″ Long Plastic Spacer

These Items will be a little tricky to get. If you’re in the US, you can go online and order from a company called McMaster Carr. I have the part numbers listed on the blue prints that I’ve used. However when I put the antenna through the ringer (tests), I will see if I have to change the part numbers to something else. I have been considering using plastic rivets instead of shoulder washers because I am afraid that the adhesive (epoxy) will not hold the plastic shoulder washers to the boom. If you get different washers or insulators, The dimensions will differ from what I have on my blue prints, so please change dimensions accordingly. If you do order through McMaster Carr, They will only sell the washers and spacer in packaged amounts. If I recall the small shoulder washer came in a pack of 100pcs, the larger shoulder washers came in a pack of 50pcs and the Spacers came in a pack of 10. It’s great because I ended up making a bunch of antennas w/o having to make an extra order.

  • Glue or  epoxy.

Anything that you know will bond plastic to metal and will survive the elements (rain, cold, ice, snow, heat, wind). Still a good idea to use even if your using plastic rivets.

  • 6pcs – 9/16″ Long #8-32 Screws

I would suggest using stainless steel screw as it will survive in the elements longer

There are optional things that you buy like Sq caps for the boom and vinyl caps for the ends of the elements for water and safety protection.

There is some more paper work to do (Grrrrr). Now that we have all these neat numbers and material, We should at least have some kind of drawing to help us when it comes to actually cutting, drilling and tapping these parts. I assume that your building the antenna for one or two reasons which are that you either don’t have enough cash to purchase a commercially made (and tunable) Yagi, or that you actually want to learn how these types of antennas work. So let’s take some more time to layout the antenna so we can have something to use when we’re cutting, drilling and tapping.

I am going to use software called “AutoDesk Inventor 2011” which is a 3D design software that is used for CAD (Computer Aided Drafting) purposes. This software will let me make each part in 3D and assemble all the parts to make sure of proper fitment. This software will also let me create Blueprints based on the information I typed into the software. If you can’t get your hands on any type of this software, no worries. You can do the same thing on graph paper.

My Results are posted below. Please note that I’ve included all the information that is needed IN the Blueprint for those who just want to download the prints and fabricate w/o reading this article. However the information listed on the prints (other than the dimensions) have only basic information for experienced fabricators/ antenna builders.

**** INSERT BLUE PRINTS ****
(Still working on them, please check back)

Now that we have all the dimensions and a print, LETS GET FABRICATING!

Here is a list of basic tools that are needed. Most Hams have these tools or can get access to them. Following this list will be a list with the preferred tools that would make the job faster, smoother and more accurate. However the majority of people do not have a lot of the items

Basic Tools Suggested:

  • Hacksaw
  • Measuring Tape
  • Marker
  • Drill
  • *Various Drill Bits (Ranging from .125″ to .750″)
  • 8-32 Bottoming Tap (With T Handle)
  • Bench Vise
  • Sandpaper (120 grit)
  • Scratch Awl/Scriber/Etching pen (or anything that has a sharp point that you can easily handle)

Preferred List Of Tools

  • Metal Chop Saw (With vise)
  • Vernier Calipers (6″ or bigger)
  • Automatic Center Punch
  • Marker
  • Drill Press (With a vice able to hold SQ and Round tubing/stock)
  • *Drill Bits (Various to .750″ [or 3/4])
  • Files or deburring device

* – For those who don’t have .750″ drill bit, depending on where you live,  a 3/4″ Drill bit can get expensive. I would suggest either a step bit (still expensive) or a 3/4″ countersink (at 82 degrees). Drill the specified hole up to the biggest bit and then finish it off with the 3/4″ countersink. Since it’s aluminum, it will not damage the countersink and you will be able to counter sinks holes on other projects (DO NOT COUNTERSINK HOLES ON THIS PROJECT!

Lets start off by cutting all the aluminum rods (elements) and tubing (boom) to the correct lengths by using the tape measure. The blueprint posted in this article shows both decimal and fraction to the nearest 32nd of an inch.


(elements shown cut to size with a band saw)

After you cut the elements and boom to length, It’s time to layout the hole pattern on the boom and each element

I used a red pencil to mark the location along the boom. Then I marked the center of each location using a pair of verniers and used a marker to make the center point more visible.

When marking the elements it’s a good idea to mark the center point twice. Once from each end so you know that your exactly on center of the element. With the driven elements, you just need to place a mark at 3/16″ in from only one edge.

Using a drill or drill press with a small (>.125″) drill bit. Drill pilot holes on every center mark on the boom. DO NOT DRILL THROUGH THE BOOM! Only drill through the side you marked unless your using a bridge port mill that has a perfect 90 degree head.

Also drill pilot holes at the marks of each element. Once again, DO NOT DRILL THROUGH THE ELEMENT! You will only want to drill half way through the element. A bit of advice is to measure from the tip of the drill bit 1/4″ up and use the edge of some masking tape to tell you where to stop when drilling.  If you feel un-easy about drilling the element, you should have a couple of inches of scrap rod that you can test both drilling and tapping on.

This photo shows pilot hole being drilled into the boom


This photo shows the Pilot Holes drilled in each element

After drilling the pilot holes, time to open the holes according the blue print. With the elements, I suggest using a .120″ (or #31) drill bit as the element could wobble causing the hole to open up a little more. With the boom I would start with opening the holes where the elements slide through first! Then switch to the 3/4″ bit and open up the holes where the driven element slides through. Switch back to the pilot drill bit, insert the plastic spacer that will hold the driven elements and using the two holes on the top of the boom as guides and drill halfway through the plastic spacer. Then open the rest of the holes to the correct size.

The next step is to tap each element with a #8-32 bottoming tap. If you can get your hands on a bottoming tap, you can take a regular tap and break the head off it and grind/file it flat.


This photo shows a element being tapped. Try to make sure your tap is 90 degree and straight.

After everything is cut and drilled and tapped to size. It’s time for assembly. Assembly is pretty stright foward.
Glue/Epoxy all  shoulder washers/rivets into place and let dry. The driven elements are going to slide into the plastic round spacer. Make sure that each side of the driven elements does not come in contact with each other. Then slide in the reflector and directors and secure them with the 6-32 screws. When finished I placed more epoxy around the elements (NOT THE DRIVEN ELEMENT) at the point where they meet the boom. I did this because I don’t plan on taking apart the antenna.

Attache your coax to the driven element making sure you don’t have the connections contacting the boom.

You should hopefully have a functional 5el VHF Yagi

Here are some reading I’ve taken with a analyzer that I borrowed.

At 144.42Mhz, I got a 1:1 SWR with an Impedance of 48ohm.

 

At 146.02Mhz, I got a reading of 1:1 SWR with an impedance of 46ohms

At 147.72Mhz, I got a SWR of 1:1 and an impedance of 44Ohms
These readings were taken in my house with the antenna mounted to a wood broom stick. When I got the antenna into the attic I took another set of readings before I gave the meter back and I saw that a slight change on the values. Can’t wait to get it outside.

If you plan on making your own Yagi, please take ALL SAFETY considerations into effect. Know and respect all the tools you are using and when it comes to installing your Yagi,  make sure the antenna with not come in contact with any utility lines.

If you are using the plans from this page, please note that your results may/will vary from what I’ve made. Since I’m new to antenna making, I would not want you to risk any material/money. Please confirm your findings with someone who does know before purchasing or building. These are just my notes on what I did to create an antenna.

 

 

 

Sources Of Information:

Peter P. Viezbicke, National Bureau Of Standards. “Yagi Antenna Design”. U.S Department of Commerce/NBS  Tech Note 688 (Dec 1976). PDF (Sept 2011)

G.R Jessob, and  R.S. Hewes. “Radio Data Reference Book” (ISBN: 1872309305)  Radio Society of Great Britain; 6th edition (November 1995)

Unknown Author (N4UJW?). “Basic Yagi Antenna Design For The Experimenter”.  YAGI ANTENNA DESIGN BASICS. Web (Sept 2011)

Martin Steyer (DK7ZB). “DK7ZB Yagi – 144Mhz-Yagis”. DK7ZB Website. Web (Sept 2011)

ARRL, R. Deam Straw. “The ARRL Antenna Book: The Ultimate Reference for Amateur Radio Antennas, Transmission Lines And Propagation.” American Radio Relay Leauge; 21st edition (May 2007)

Peter Knott. “Wire Antenna Modelling with NEC-2”. Antenna Engineer 8/12/2009. PDF (Sept 2011)

Daniel C Lester (KE9SE). “The Effects Of A Conductive Boom On Element Lengths”. VHF-UHF  Basics (9/17/2009). Web (Sept 2011)

Guy Fletcher (VK2KU). “Effects of Boom and Element Diameters on Yagi Element Lengths at 144, 432 and1296 MHz”. ARRL QEX Magazine (Jan/Feb 2000).

Software Sources:
Arie Voors . “4NEC2” – Web – (Freeware) Program Used to Design and Simulate Yagi (and other) antennas
Autodesk Corp. “Autodesk Inventor 2011” – Web – (Trial/Edu/Paid) Program used to Design and create blueprints