I’ve recently picked up and made some new gear for my rig. Still shopping around for a higher powered radio, but that can wait until the upcoming holiday season. Let’s go ahead and take a look at the new kit.
ExpertPower 14.5″ 2M/70CM Dual Band SMA-Female Antenna
This is a pretty solid upgrade to the stock antenna for the radio. I’m able to get clearer reception over the stock antenna, and I can hit the closest repeaters with a decent signal quality report. It’s a 1/4 wave monopole rubber duck with a floating ground plane, so it doesn’t perform as well sitting on a desk as it does in your hand. Putting a small piece of metal underneath the radio seems to improve the quality without requiring me to hold the thing the whole time.
Homebrew Single-Band 2M Slim-Jim
Dual band antennas definitely seem to be all the rage, but I’m also interested in antennas that will give me solid performance on the bands I use most often. I picked up some air-core twin lead 300 ohm antenna line, some RG8/X 50 ohm feed line, and lots of fittings. The Slim-Jim is an improvement on the traditional J-Pole antenna, but also extends the primary radiating antenna element an additional 1/2 wave folded over where the traditional J-Pole simply ends.
I was getting decent readings from the SWR meter with this antenna design with only a ferrite bead balun at the antenna feedpoint, but something in the back of my head was telling me that I needed to add a balun to match the feed line impedance with the antenna, so I did! It’s covered in heat shrink in the photos, but the balun is a cheap ferrite core wrapped in a 4:1 Guanella winding with small gage wire.
After everything was put together, I whipped up a holder and stand from 3/4″ PVC piping and joints, and it works pretty well. I can’t fit the balun through the pipe, and I’m going to need to upgrade that part to 1″ PVC, but atleast the recipe works and functions better than the 14.5″ rubber duck!
I’m using a SMA-female to SO-239 socket pigtail to connect the handy talkie to the antenna, and I suspect that I’m getting significant insertion loss from that. I have some similar fixtures that are a single component, and I believe that their arrival will further improve my reception. It’s still the best antenna I’ve tested for 2M operation, and I’m able to talk clearly on repeaters that wouldn’t even open their squelch for me before. I can break it down for mobile operation, but it’s not as convenient for that purpose as the rubber duck antennas.
I’ve got some designs I’m considering for making a 1/4 wave ground plane antenna for 2 meters. Some designs incorporate a second antenna element to make it resonant for 70 centimeters, but I’ll wait to bring that part once I’ve got the recipe down for the 2 meter single band version.
I would be a flat out liar if I claimed that I did all of this on my own in a vacuum. I scoured the internet for sources on antenna construction, baluns, and matching antenna impedance to the feed line. Some sources are better than others, but they’ve all been helpful. Here’s some that helped me out with this particular project:
So far, I’ve been scanning the local North Atlanta repeaters around Cobb, Fulton, and Gwinett county. I’m able to pick up fairly strong reception from some of the local repeaters, and I’m very impressed with the quality of freely available software that was available to help me get on the air. I’m presently making use of an inexpensive 4 Watt Baofeng UV-5R. I’ve been working with computer systems, unix system programming, embedded programming, and electronics for nearly a decade and a half, and it was only natural that I was going to come across some use cases that would require a radio license.
Initially, my interest was video downlink connection from model aircraft, but I’ve since come across digital modes for weak signals, and it’s consumed my interest. I have some designs captured in schematics for a Texas Instruments based PCM2900C USB sound card interface with auxiliary input/output and monitor. I’ve looked at the Signalink USB, and it’s interesting, but ham radio is about cooking up your own mad science! I’m still working on laying out a reasonable PCB before sending the order off the OSHPark or one of the other fine PCB bundling services. I intend to publish my work under the Creative Common Attribution Share Alike license when it’s ready.