Project – NT1K

Power Pole Distribution Block

Now that my station has grown, I have quite a bit of equipment that requires 12-14Vdc of power. In the past couple of years I decided to start using Anderson Power Poles. I decided to use them as it’s starting to be the standard of some organizations and It’s easy. My only complaint that I would have is that sometimes the connectors can loosen up and doesn’t require much force for them to come apart.

At this point I have a very minimal setup that needs to be expanded. I have a pigtail off the power supply and set of power poles on each device. If I wanted to use one device, I would have to disconnect power from one device and put it on another.

The obvious solution to my problem is the use a distribution panel. There are some commercially made panels that use Anderson power poles but being the cheap ham that I am, I figured I can find a cheaper way.
While at a local hamfest this past weekend, One of the vendors had a bunch of products that use the Anderson Power pole. Two of those products has caught my interest. One of the was the “EZ-Gate” by ham source and the other was distribution block by Quiksilver. The EZ-Gate is similar to the PWR-Gate by West Mountain Radio but doesn’t have LEDs or Fuses. The EZ-gate is half the cost of the PWR gate and this would allow my station to instantly switch to battery backup during events like field day or when the power goes out in my house. The power distribution block was just a simple 4-way connection using power poles and priced at $20. I thought the price was fair but I thought would be cheaper and fun to make my own at home, For the price of one block, I decided to get twenty pairs of power pole connectors.

Having no clue how the little distribution blocks were made, I thought of way that I think it was done with the commercially available ones. I used 12ga soild copper wire to connect everything together.

Here is a photo of what I started with and the final product.

I cut 4 wires about 1.5″ long and placed the connectors on each end and did a quick assembly to check the gap between the sets. I wanted the gap to be short as possible so the entire block would remain rigid. I also cut and bent two additional wires to act as a “link” to the top and bottom sets.

Here is one of the wires that I crimped the ends on. After crimping I soldered each end to make sure of a good connection. Please note that the connectors on each wire are opposite angles from the other side. At this point I installed the wire and marked the location where the link will go with a sharpie.

Two of the four wires, I soldered one “link” favoring one side of the wire.

Here it is halfway assembled. you will notice the link on the positive side very close to the connector. When the other side will be installed, the other link will be close to the negative block on the opposite side.

Before connecting the other side, I used a pair of pliers and curved the links around the top stack of the link.

After completely soldering the links and installing the other end, I wrapped the positive side in plastic. If I were to do this again, I would solder, install heat shrink tubing both leads and then install the other set of connectors.

For what I would have paid for ONE commercially produced block, I’ve made two blocks and had and also have an extra set to make a patch cable or pigtails/adapters.

It’s no rig runner but it works and does what I need it to do.

Thanks for reading!

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

Happy New Year!

Just want to wish those who visit this site a Happy New Year. I haven’t been able to post many articles but that will change and stay tuned. I recently acquired a Heathkit SB-200 that needed some work so I’ll defiantly have a write-up on that. I also fabricated a 5EL VHF Yagi which I will show you step by step on how I designed, fabricated and tested (somewhat) the new antenna. And there is a possibility of my first HAM related home-brew equipment that I’ve seen in QST. It’s in the planning stages but I think it’s going to happen.

Hello APRS My old friend.

I’ve come to talk with you again.

APRS – ™ By: Bob Bruninga, WB4APR Http://www.aprs.org

Back in 2001 when I first got my license. I was interested in APRS because it was something I can do with my new license. I went as far as setting up a part time digipeater and after only a couple of months, the digipeater went down and lost interest in APRS because the cost of a GPS receiver at the time (even though GPS is NOT a requirement to listen or participate on the APRS network).
GPS receivers are a lot cheaper compared to 10 years ago and I have a old Garmin GPS-V lying around. So I figured this would be the perfect time to get back into APRS. For those who don’t know what APRS is, It’s Automatic Packet Reporting System which is an Amateur (Ham) based system for real-time communications of information using a digital protocal (AX.25). There are many possible things you can do with APRS. You can send (Short) text E-mail, SMS Messages, send weather data (Which the NWS uses) and when hooked up to a GPS , will send position data. I am not going to go into much detail because there are websites that are dedicated to APRS.
I am going to be doing a couple of things with APRS. One thing is that I am going to set up a part-time iGate (internet gateway) to make use of the frequency scanner and antenna that is not being used. Packets of Information received from the scanner (tuned to 144.39mhz) will be sent over the internet using the APRS-IS network so it can be databased and displayed on such websites as aprs.fi .

The other thing I want to do is location tracking. In order to do tracking you’ll need 2 or 3 things. You’ll need a GPS receiver that has an output for NMEA data, TNC (Terminal Node Connector) and a transceiver (VHF [144-148mhz] is Most used). As stated earlier, I have a Garmin GPS-V lying around and I also have a Kenwood TH-78A. All that is missing is a packet TNC. A Real TNC can cost $100+ and needs a computer. However there are units designed and built for APRS that will encode the data from the GPS to the AX.25 protocol and transmit the signal using the transceiver. I’ve purchased one of these units called ” TinyTrack3+” from a company called Byonics. It’s as basic as it gets. You can either buy it as a kit or assembled, with or without a GPS Receiver, with or without cables for your transciver or with or without cables for various GPS models. I ended up going with a solder and assemble your self kit without any extra cables because I wanted to invest the least amount of money in it as possible.

Here is the kit as you would get it in the mail. It comes with the componets, board, case and instructions.

Here is the board soldered up. I used a 35W Pencil type soldering Iron. I filed the tip a little bit to assure that solder flows to the tip. It took about 1/2 to 3/4 of an hour to solder. If your new to assembling boards, I would go to the Byonics website and download the manual because the online .pdf manual will cover the assembly and everything else in great detail. As long as you follow the step by step instructions, it will turn out great. For newbies make sure the diodes are going in the right direction, LEDs in the right direction and make sure the notch (little cutout) is aligned with the silk screen image.

Now that board is done, time to make some cables! (Since I didn’t order any)

Here is the cable all assembled! It’s a DB-9 Connector (Radio shack P/n: 276-1538 US$2.69) , Pos and Neg power cords with Anderson power poles attached so it could powered by many different sources (7-35vDC), Sacrificed speaker microphone from the Wouxun for its cable, Ferrite Core choke (Optional, Radio Shack P/N: 273-105) and the DB-9 Case (Radio Shack P/n: 276-1539 US$2.09). I Got the wiring diagram from the Byonics website and took about 1/2 hour to make which ended up costing me around $5 since I already had the cable, choke and power connector

Just an FYI, I sacrificed a speaker microphone from my Wouxun. Power-Werx which distributes Wouxun products (as well as the power poles), has the exact same cable for this application for sale on their website. They also have a similar one but with a cigarette lighter plug (Both for US$20). Byonics also sells cables for this and many different radios. Also note that that wouxun speaker mic layout is the same for kenwood HT’s!

After you assemble the tracker and the cable. Apply power to unit and hopefully it comes to life by flashing the yellow and green LEDS three times. Only thing left to do is to program the tracker using your computer. This point it can get tricky. The TinyTrak3 needs a NULL modem cable (Or adapter) to program it and possibly a gender changer. I found that I didn’t have a null modem cable, all I have are straight through cables. Since I didn’t want to wait for an adapter I made one from old computer parts lying around my house

Here is the cable that I made from parts out of an old 486 that I had in the attic. It’s not pretty or rugged enough for daily use but once you program the Tracker and are satisfied with the operation then you will most likely not have to program it again.

Here is the complete setup. Right now I have the unit running off a 9V battery. I also used a cigarette lighter plug with power poles connected to it. Depending on how you programmed the tracker, It will only send when there is data from GPS. There are limitless things you can do with this setup. For SOTA members (Summits On The Air), They can bring this along with them so others can see their progress in their hike. If you helping out in a public service or public events which ham radio operators are helping, you can show your location to HQ without even telling them. It makes things a lot easier.

Here is my first track. I learned a lot when doing this. I found that my handheld in the truck has a hard time communicating with the digipeaters in the area. I might purchase a small 1/4″ wave mag-mount or a duplexer and switch to my dual band antenna for when I am running APRS in the truck.

Modifications

I added things to the Tinytrak3+ which I think will make it better for me to run. If I had to be really critical about the tracker is that the DB-9 connectors did not come with mounting screws. The first test out with my truck the power/radio connector became loose and eventually lost power to the tracker. To fix this I went scavenging parts off a old computer.

Now I can secure both the power and GPS connections. The screws came off the LPT and monitor ports of an old mother board. There is a small amount of space between the back plate of the connector and the board. So I had to grind down the bolts and nuts so It would not touch the board.

Another issue that might come is when I am portable (walking). More likely the power source for the tracker for this purpose will be a 9V battery. The tracker with all the LEDS running will consume around 18.6ma which means a 9V battery (.370Ah avg) could possibly last for about 9-12 hours (60% discharged). If you turn off the LEDs, the power consumption is 6.6ma. On a 9V battery, the tracker could last around 30 hours. The TinyTrak3+ can run without the LEDS by cutting a lead (tells you how in the directions). If you using a high-capacity 9V (.580Ah)with no LEDs it could last for more than 50 hours so it might be beneficial to cut the lead and add a jumper. The down side is that you will not know the status of the Tinytrak.

So what I did is cut the lead on the board and installed a bridge (shown in the picture above with the blue jumper). When jumped the LEDs are operational.
Also pictured are 2 bridges installed (on the left side) for jumpers J5 (outside pair) and J6 (inside pair). If J5 is jumped it will switch to what was programed in the secondary tab in the program (Program 2) . This would work great for an event which required either a different call and/or different settings. After the event, you can switch back to the primary settings. If J6 is jumped it will send a signal to power on the transceiver. This would involve another board with a relay to put power into the transceiver or modifying the transceiver. I don’t plan on messing around with it any time soon but since I am soldering on jumper bridges, why not.

Overall it was a really great build and I am having a blast with APRS. My plans are to find a way to make it all fit into a nice tiny package that I could carry when hiking or driving.

73 and thanks for reading!

Homebrew GMRS 3 Element Yagi

Since I’ve built a ton of J-Poles and wire Antennas, I’ve wanted to build something different. I decided on a 3 element YAGI built for GMRS that is directly fed with 50ohm coax. After a couple of failed yagis and the help of another ham on QRZ.com forums, I finally built a Yagi that works! The reason I’ve chosen a Yagi built for GMRS is due to the ultra high frequency, which ends up being a small antenna. If I were to mess up (Which I did), the material cost would be low. I also wanted to use it on a GMRS repeater in the area.

The first Design I used is with a Web Site that has a Java base applet to design the Yagi, After getting all the Dimensions from the website, I went to work building the antenna. After everything was done, I learned two things. One is that my drill press does not drill straight (90 Degrees) through the tubing. The other thing is that when I hooked up the antenna to a simple SWR Meter, That didn’t work either (Pegged the Meter). At this point I got frustrated and posted my issue on QRZ.com. A Ham by the call of WB3BEL (Harry) took my dimensions (That I got from the applet) and plotted my antenna into 4NEC2 software (Like EZNEC but freeware) and it would not work for the center frequency of the GMRS Band (or any part of the GMRS band).
WB3BEL actually re-designed the antenna to where it would work so I give him credit and major thanks for help. I took his Dimensions, Modeled the antenna for fabrication and built the antenna. I Hooked up the antenna to a transceiver and SWR meter and got a 1.2:1 SWR and a 1.5:1 SWR on the outsides of the GMRS band. The Design is calculated to yield 7.5Dbi of Gain. Considering connector and cable loss (Lets say 4Dbi using 50ft RG-213 W/ 3 SO-259 Ends and a Barrel Connector) still yields gain of around 3.5Dbi which is not too bad.

Here is rendered Image of the Antenna. The elements are Insulated from the boom using plastic shoulder washers for the Reflector and director. The Driven Element is insulated using a 0.750(OD)X.375(ID)X1.5″(L) Plastic spacer. Since the elements are going THROUGH the boom, It will make the elements electrically shorter so you have to compensate for the loss by adding 0.279528″ (7.1mm) to the element to correct the effect (Boom correction). The elements are secured using #8-32 Screws screwed to the boom. The screws are also insulated from touching the boom. The screws do not make any significant changes to radiation pattern of the antenna as long as it’s insulated from (not touching) the boom. I did notice that the screws actually lowered the SWR a tad which is great.

I didn’t add a matching network to the antenna because I wanted an easy to build and assemble antenna which is the entire point of this article. The antenna is fed using RG-213 Coax with terminals soldered to the core and shield. I tried to keep everything as short as possible because this and the ring terminals effect the performance and SWR of the antenna.

Here are a couple of screen shots from the antenna software that show the Radiation Pattern and gain. Nothing special here.

Here is the calculated results for the SWR of this Yagi. Please note that it’s in the ball park. By adding screws, coax leads and the ring terminals, it could or will effect the final pattern and/or performance of the antenna.

Here is a SWR Shot. As you can see, I don’t have a very good meter. I would like to buy a HF/VHF/UHF Antenna analyzer for my Antenna builds but I don’t think that will happen in the near future.

Here is the complete Antenna.
Overall it was a fun little project. It took a short time to build and it’s a great directional antenna with some gain to help your signal on GMRS reach its destination.

Continue reading if you want to build this antenna.

Continue reading “Homebrew GMRS 3 Element Yagi”