Motorola – NT1K

Custom 19″ Cabinet for a portable repeater.

This project is more related to sheet metal design than Ham Radio because the fact that it could be used for more than just radios.

A friend/fellow operator asked me if I can build a 19″ rack mount for a portable repeater. I’ve learned over the years to NOT volunteer my time and/or services because it can lead to a lot of trouble and out-of-pocket expenses. But I owed it to him and I actually always wanted to design a desktop rack mount. Since time is of no worry, I felt comfortable working on this project.

For those who don’t know what a “19 Inch Rack Mount” is. It’s a standardized frame or cabinet/enclose for mounting equipment modules (i.e computers, radios, telecom equipment, and etc). These modules have a front plate that is 19″ wide which have holes/cut outs to allow the module to be mounted to the frame that has a standardized pattern. Since it’s a (EIA) standard in the industry, designers and fabricators have the basic foundation to design their product off of. There is also a 23″ rack but the 19″ dominates the market at this point in time.

Having a standardized system makes the design aspect a lot easier to tackle. All I really had to figure out were the dimensions of the Motorola CM series radios.
Once I had that, It was actually quite easy to design.

I’ve personally dealt with these type of racks in fabrication, but I have never had a chance to actually design something using this standard. Hence the main reason I am making a this cabinet. I’ve learned quite a lot from this project that will make me look just a little harder when it comes to similar projects.

Here are some pictures of the project.

Here is the 3D rendering of what I designed. On a lot of my projects that involves showing the image of the render before fabrication, I added a dollar bill to the project as a reference to size. It actually took about a couple of hours over a span of 3-5 months to design.

The laser doing it’s job. It’s about to cut on the front panels

Here is everything after laser cut in the flat. Little bit of deburring to take off any dross/slag and off to the bender!

I wasn’t able to snap a picture of the machine actually bending up the cabinet but this is the machine that did it. It’s called a Panel Bender and works great for projects like this. The tooling is already installed and all you do is punch in a couple of numbers and off to the races. With this project and the time constraints, I bent every part by eye without using the CNC gauging system (takes longer to program the machine). I knew I was going to bend by eye so when I programed the part for laser cutting, I added little cutouts to physically show where I am going to place a bend. Line up the little cutouts with the tooling on the machine and it will put the bend within the tolerance that I need for assembly.

Here is the box after bending. I did a test fit by assembling all the parts. In the design I added 1/8″ diameter alignment holes. These holes when lined up and used with cleco pins (sort of like removable rivets) , will temporarily hold the panels together. This will allow me to either weld, spot weld or take one cleco pin out at time and replace it with an actual rivet.

Here it is all assembled and ready for paint. I decided on a black texture powder coat because it’s used often in the industry. Plus it hides my fat greasy fingerprints quite well.

And there she is… Ain’t that a thing of beauty? I placed a 2U power strip just to illustrate that how universal it can be. Well that’s basically it. This little article is to show to process from the thought to design and from design to build. If I were to even build something like this, I would use thicker material and stick to the specs on the standard a little more closely. I would also add handles and reinforce the area where the handles are mounted.

Edit (9/30/2011): Here are some more photos (Click to enlarge)

Here is it at the house…

Here is a different view. On the bottom of the unit is a surge strip. When I fabricated I only made 3U panels so if I were to install devices that took up 1u or 2u then I would have a gap. So I made some additonal panels which haven’t been painted

Here is a upclose shot that will show how the panels or modules are mounted. Depending on the design, some rack systems have sliding frame rails to extra weight support. The silver looking thing you see is actually a spring clip with a floating #10-32 nut. Back when these racks were first being designed, instead of using a square hole with a captive nut, they just had regular round holes that were drilled and tapped. Problem was if the threaded hole were to become stripped due to major use or misalignment, then the entire unit could be scrapped if it couldn’t be repaired. With the new system, you can just pop in a nut where ever there is one needed. If it gets stripped, just replace the nut!

Here a picture of the back of the unit. I created a 2X3″ in opening to allow cables to be routed through. When not in use, the gasket-ed cover can bolt right into place using two #10-32 screws that screw into pressed inserts on the main body to create a nice air/weather tight fit (even though the rest of the unit is not air tight).

Here it is with the radios installed. Considering this is the first time I actually got to physically handle the radios, everything lined up okay considering I was using the specs from a similar radio for it’s dimensions.

Overall it was a great build, I just might build another one and apply what I’ve learned on the new box If by some chance you have the chance to fabricate something similar, I would use 1/8″ Aluminum or 12ga (.105″) steel.

APCO 25 (P25) and DSD

Since I have a radio capable of transmitting Digitally using the Project 25 protocol. I wanted to test it out. The only issue is that there are no P25 ham radio repeaters in receiving distance from my house and I do not have another P25 radio to communicate with. After searching around Google, I found some websites discussing software that will decode the digital signal and convert it to analog over your computer’s sound card.

Hardware Needed:
Scanner – I guess it can be any kind as long as you can get at the discriminator output. I used a Radio Shack PRO-97.
Audio Patch cable – From the discriminator output to the computer
Computer – Not sure what the minimum requirements are. I used a 1.5Ghz single core AMD (Circa 2003) and a motherboard with a built-in sound card.
Sound Card (If you computer doesn’t have Sound Card) – I don’t think there is a need to go out and spend hundreds on a card that your going to use for this purpose. The money spent on a expensive card could have been spent on a scanner that can decode APCO25. I’ve found that a sound card using the AC97 Codec works the best.

Software Needed:
Linux OS Or Windows – That’s right L-I-N-U-X!! ~~DSD Will NOT run on ANY KIND OF WINDOWS OS. Let me type that again. DSD DOES NOT RUN ON WINDOWS!!!~~ Sorry but I had to do that. I’ve used UBUNTU Ver 10.04 . At the time of writing this, the current version of Ubuntu is 11.04 . For some reason DSD DOES NOT WORK WITH UBUNTU VERSION 11.04 . The reason I choose Ubuntu is that it’s downloadable, free and has a Graphic user Interface. Since I never Ran Linux before, I felt a little more at home with Ubuntu. You can run a Dual Boot system so that when you start the computer, you can have a choice of which Operating system to boot into. With Ubuntu you can also run Ubuntu off the CD instead of installing the OS on the computer. Please note that there is a lot of reading in installing Ubuntu which I will not cover on this website. Google questions you have and I’m sure there is an answer out there

DSD (Digital Signal Decoder) – This is the software that actually takes the digital signal and decodes it.
Mbelib – This software actually takes the decoded information and synthesizes it so you can hear the decoded audio.

DSD and mbelib can be downloaded from here (See note at the end of this writeup)

After modifying your scanner and getting Linux to run, download Mbelib and DSD in Linux and remember where they are located. In terminal CD (Navigate) to the directory where both Mbelib and DSD are located, Unpack both Mbelib and DSD and then install Mbelib first then DSD. If your very new to Linux and have some computer skills, this thread helped me out.

After installing everything, in Terminal type “dsd” (without quotes) and If all goes well. The last line should be “Audio In/Out Device: dev/audio”
Errors that I got at this point mostly have to do with sound. Either your sound card is being used by another application (even the sound control panel) or DSD is not calling up the correct sound card. DSD is defaulted to use sound card device 0 (zero). So if your sound card device is in a different spot then you need to tell DSD the location for the sound card. You can check where your soundcard is (if it’s installed) by typing “aplay -l ” into terminal. If it’s device 2 for example then you type in terminal “dsd -i /dev/audio2 -0 /dev/audio2”

I’ve uploaded a video showing up how DSD works with APCO 25 (P25, Project 25). It also works on other digital modes but I have not yet tried.

I am loving this software. It’s not the easiest software to install or use but if your into scanning and just even wondered about Linux. This is the perfect project to get your feet wet in Linux.

Please note that I am not an expert on the DSD software or Linux. Most likely I will NOT be able to help you if you’re experiencing problems. The install went so great for me and worked so well that I wanted to install it on another computer. After installing it on another computer, I had nothing but trouble. The good that came out of having a hard installation is that I learned a bit about DSD and Linux.

Thanks for reading

UPDATES 10/24/2011
I haven’t been using DSD much as I’ve been out of touch with APCO but I was informed by a user on Youtube that There is a verison that runs in windows.

Here is the link to the RadioReference Thread

Basically what the Author did was compile all the stuff from the linux version of DSD into a windows .exe file. If you just want to listen to P25, Download the version in the 3rd post of the thread. All you have to do is un-zip everything into a folder and run dsd.exe

I’ve tested it against my XTS3000 (P25) and everything looks and ran great. I think the Audio was a little better sounding on my Linux box but the audio is still legible and I’m glad to now have it on a windows box. Maybe I’ll listen to it more often.

Make sure to plug into the discriminator tap and put the other side into the LINE-IN (Blue). Before loading DSD make sure that the LINE-IN is your DEFAULT recording device and you should be all set. If you try to do this while the DSD is running you can run into issues just like when it was in Linux.

Thanks to the RR crew because it makes scanning more fun and less expensive.

I’ve gone Bat$#!t – Hello Moto(rola two-way)

In the past couple of weeks I picked up a couple commercial two-way radios. I’ve purchased a Motorola Maxtrac 300 (Mobile) and a XTS 3000 (Handheld).

I’ve been a fan of commercial radios since I got my hands on a HT1000 and beat it up pretty good. I’ve dropped it, thrown it, threw it into a puddle and who knows what else and they always worked out.

There are PROs and CONs about owning a commercial radio for Amateur use. One of the CONs is programing. Unlike amateur radios, the majority of commercial radios have to be programmed. With Motorola, depending on the situation, the software that is used to program these radios will end up costing as much as half (or more) of what you purchased the radio for. You could also have a local dealer program the radio. Another one of the CONs is the ability to change the frequency “On The Fly”. You can only change to a frequency (Channel) that is programmed into the radio.

One of the PROs are that you will get a radio that is built to public safety and/or military specifications. These radios can take a lot more abuse then it’s amateur counterpart. Another PRO is that these radios are built as “Part 90” (Public safety, Private business, municipal, etc) radios. That means you can use these radios in both the LMRS and Amateur frequency blocks. Your not allow to take a amateur radio and modify it to transmit in the LMRS. So if you have a job that uses radios in the LMRS blocks or you want a radio that can do both GMRS/UHF (Or MURS/VHF) then you will have a radio that will possibly cover all 3 possibilities.

This is the Maxtrac 300 I got on e-bay for around $100. It was being advertised as a 430-470mhz split which is rare but when I hooked it up to the computer, it was the 450-470mhz split.

Just a note for anyone that is looking to buy this or it’s GM300 brother on eBay. Make sure the auction has the Model number in it. For example, the model number D34MJA7JA5AK means that’s it’s a 10-25w (2nd Number[3]), UHF (3rd # [4]) Conventional (Numbers 4,5,6 and 7[MJA7]) 32 Channel (8th # [J]) A5 HEAD (9,10th #) Revision K (Last Digit).

So now you know your getting 10-25 watt 32 Channel UHF radio. However these types of radios have 2 splits per band. On Uhf you could get getting a 403-430 or 449-470 split. I’ve read that there is a 430-470 Split RF but I have yet to see it. The only ways to tell what split the radio is, by looking at the radio in the RSS (programing) software or actually opening up the radio to see what the part number is on the RF Board. So be careful if your looking for a Ham band Maxtrac.

This is my Motorola XTS 3000 UHF Handheld radio. I purchased this item because the “But It Now” price was just where I wanted it. Another reason is that it can decode/encode P25 Digital. Always wanted to mess around with it and now I have the chance. Only issue is that there is only two P25 systems for ham radio in the state of Massachusetts and they are both located out of range. If there is enough interest in the area, I would like to setup a repeater capable of P25. We’ll see…

Thanks for reading!