Category: Electronics

Building a Ham Radio Power Supply

Ham Radio Isn’t Cheap

Much like shooting, ham radio is expensive. I think all fun hobbies are. But after spending $820 for the radio, I wasn’t in the mood (or the financial state) to drop another $100 to $150 on an Alinco Power Supply. Slick as spit, but not worth it.

So, here is what I came up with:

My power supply has the following features:

  • Hacker cred. I put it together, and it looks nice and works great, on 2M at least.
  • Dual USB ports, for keeping a phone topped off.
  • A cigarette lighter, for powering/charging a baofeng or anything 12V compatible.
  • Dual Anderson Powerpoles on the rear, for the ham’s favorite 12V connector
  • Uses a standard computer power supply cable.

So, here is my Bill of Materials:

A few build notes:

  • I crimped the powerpoles using my standard channelock wire strippers and then soldered them with my hakko. This gives about as good as a connected as you can get.
  • I used standard spade connectors (though mine are from Menards), again crimped and soldered, to connect everything to the power supply unit.
  • Most ham radios expect 13.8VDC, instead of the 12V this one was outputting. That’s okay, there’s a dandy reostat you can use to adjust the output power. I had mine set for 13.81V and its drifted to 13.84/5. I suspect it has to do with the construction and actually powering the unit up. However, my 857 will tolerate a +/- 10% range, so eh. I’ll adjust it again the next time I fire it up.
  • Take care when making the AC Mains connections. I am using a cut\trimmed piece of a PC power cord, with crimped and soldered spade terminals connected to the socket and to the power supply unit. I used some push on connecters to make a removable/solid connection to my socket, then put heat shrink over the arrangement to make sure I had removed and electrocution hazard, as best as possible. 14VDC will tickle, 120VAC will kill, and hurt the entire time.
  • Cut outs for the Chassis mount and PC powersupply socket were done with an x-acto knife, a ruler, and a little bit of caliper work. Everything fits perfectly. Lay out the holes you need, then visually check the marks are in the right place. Make light passes with the x-acto to cut through the plastic of the dry box.
  • This is such a gadgety thing, but it makes doing zip ties so much easier, tighter, and with practice the cut offs cleaner.

The total cost of the arrangement? Not counting the sundries I had on hand, $54.04. Not bad, a third of the cost and quite a bit more fun. You could do this even cheaper if you skipped the power powerpoles and the other features, but charging phones is good. When I first made it, I had the radio and a cut off power cord running directly to the power supply unit. It worked, and worked well, but I wanted to make things cleaner for sure.

Questions? Comments? Leave them below. 73, and good night all.

Edit: I posted this to /r/amatuerradio and generated a fair response. I would like to highlight Megas3300’s RF Choke. This is probably needed for mine as well, but so far I’ve only used this on VHF. A proper HF antenna system awaits.


Icom IC-W32A: A Work in Progress

This is contingent to my “Workin’ the Birds” Series. However, it is a more technical discussion of amateur radio equipment. The primary purpose of this blog is preserve information I want for later. However, I feel that the information contained in these posts may be found edifying for others. If you can’t look up edifying, you are not the target audience of that secondary purpose. A third purpose is a demonstration of my technical skills and abilities as well as communication. It is not working as well as I would like.

I wanted an upgrade from my Baofengs for multiple reasons and the Icom IC-W32A is the radio that I ended up choosing. The W32A is well regarding within the Amateur Satellite Radio community as one of the best. After my post on the high price and poor selection of equipment available at this time, I ended up back tracking into the early 2000’s for my “new” gear. This HT is well loved. Wear spots, but no nicks or gauges. Used, but not abused. The only thing that was missing from what I wanted (better receive, reasonable price, better channel management, S-Scale) was better channel management, though there is the option of skip programming which may prove useful.

The bad is being an ebay radio (and 10 years old), I knew I would be needing a new battery. With this particular auction I didn’t get a charger either. At this moment in time, the charger missing is a bad thing. I don’t know if the radio will even turn on. While I was willing to risk what I did on the auction, I wasn’t ready to double the bill to fail. I need to know if this thing will power on and transmit. I was able to get around this though, with an adapter from RadioShack. Two options:

Since I have all of components for option 2, I went with that. The primary reason was the low cost – $3.50 and a bit of wire and solder. You could buy an official Icom Charger, but if this thing functions well, I’ll be switching to this lithium-ion battery pack. What a waste to get the official Icom option when I’ll use it … once.

After looking around the manual and talking with people on reddit and the AmSat mailing list, I was able to determine the polarity and power output of the plug. 12V, center positive.

After charging, the radio powered up! Oh joy. I at least have a reasonably priced scanner now. Except tuning to a NOAA Weather station, I do not have audio output. Plug in some headphones, and I have sound. Great. This could be either a broken speaker, or a broken headphone jack. Without the headphones, I have a working mic. With the headphones, I do not. For now, the solution is to find a reasonably priced handset to plug in. This will work until I have checked everything else out, and insure that the radio is worth my time to repair further. It will also provide inexpensive replacement parts. The replacement will be here Monday (4/18) and I will attempt to check into my ham club net with the radio that night.

That’s all I have for now. I’ll leave this post linking various resources and information that I found while waiting and getting the radio to function to this point.

Resources

Parts

Disclaimer:

Borrowing from my podcasts, this post is not sponsored by our employers, employees, who or what have you. All opinions expressed have been, are, and always will be our own. Said opinions expressed on the show are believed to be well reasoned and insightful. If you find a topic mentioned on the show interesting and decide on further action, then it is your responsibility to research, consult your doctor, lawyer, significant other, etc and understand the full risks of such an action. Providing a link to a resource online does not certify the usefullness, safety, or reliability of the content or providers on the other side.

The information in this post is semi-technical and capable of damaging\ruining\destroying your prized transceiver. It’s not my fault if you turn it into and efficient boat anchor.

Minor Update

I’ve found that filling a bit off the bottom of the plug from radio shack makes it connect more reliably.


Fixing Over-modulation in a Cheap Throat Mic

I purchased this throat mic back in April. When I hooked it up to the UV5R, it was reported that I was over-modulating the mic. In layman’s terms, the mic was so sensitive that it was picking up my voice so well it was “overdriving,” or clipping the audio. You can see a fair example at the beginning of this youtube video:

So how to deal with the over-modulation in mics? If you have your Technician’s license, you know that this is one of the questions on the Amateur Radio Technician’s test. The answer is to move the mic further away from your mouth. But throat mics use a piezo element which translates vibration into an electrical signal. So, to work, they have to be touching the source of the vibration.

The solution is to dampen the vibration. One way to handle this is to rotate the throat mic about your neck so its not directly setting over your voice box. But, in my case, it wasn’t enough. To much low end in my voice, I suspect. In the end, the solution I employed was to put some theraband between the cup wall and the piezo element in the cup.

Theraband is basically rubber banding. Removed from sunlight, it doesn’t break down like a regular rubber band will do – an excellent quality for our intended use. Jorge Sprave uses it for his ridiculous launchers. I had some left over from a previous infatuation. If you don’t have theraband, you can use foam sheeting. I actually wanted to use the foam sheeting, much like this amazon product, but all I had was theraband. The idea was to reduce the amount of vibrations that the mic can “feel” by adsorbing some of the vibrations produced by speaking.

In the photo of the throat mic, the piezo element is located in that left hand cup. You can take it apart by removing the two Philips head screws on the inside of the band and gently pulling the cups apart. Then cut a piece or theraband or foam sheeting into a circle (a nickle is about the right size) and place it in the cup in between the piezo element and the inner wall that will be contacting your throat. Put the cups back together and then screw the screws back in. Be careful – the cheap plastic strips easily. I ended up needing to use some black electrician’s tape to hold mine together because I managed to strip out the screw holes and then lose one of the screws. I actually only needed a single piece of theraband to bring the mic into a usable range.

I used it to check into the local repeater net earlier, and heard no complaint. I’ll have to check with the fellow that pointed it out, but if I’m still over-modulating I’ll just place another coin sized piece of theraband between the cup and the piezo element. This is probably my favorite mic system to use. The acoustic tube makes for discreet listening and the mic needs to be directly on the sound source so it won’t pick up background noises.