So another year has come and gone, at least for the June VHF contest. I started prepping for the contest months ago, mostly little things, like getting switches setup to change between 2 radios, and 2 mics, replacing some high-loss coax on my 2 meter beam with some quality low-loss cable, put up the 220MHz 5 element beam… There were some bigger projects that were nice to get done as well.
One of the bigger projects that has been haunting me for about a year is the 2 meter amplifier project. I did some trading last year and picked up an FAA AM-6154 amplifier. These amplifiers are quite popular. They can be picked up around $300, require a few hours of work and just a hand full of parts to get one operating in the Ham radio bands. I am not going to go into a lot of detail on this amplifier right now, if you Google AM-6154, you will find plenty of information on these amplifiers.
What I will say about the amplifier is that it takes 10 watts or less of input power, produces 400-450 watts output power (some claim higher), and can be modified for 2 meters, 220, or 432 without a terrible amount of work. My amplifier sat untouched for several months after I took possession of it while I learned a bit about what was needed. I don’t like to blindly modify an amplifier, I like to know what I am doing and why.
There were a few issues that need to be addressed as far as the contest is concerned. I run a modified Ameritron AL-80 on 6 meters that produces around 800 watts. At that power level I have issues of RF noise making its way onto the Mic cable. I did as much as I could do without tearing apart the entire station in the middle of the contest, but couldn’t get the issue completely fixed. A redesign is coming up soon for the mic/radio system, and I hope that takes care of those issues.
On the subject of the modified Ameritron AL-80, it has been a great amplifier and has not caused me any real problems. I ran the amplifier pretty hard for about 3 hours on Sunday until I noticed that I had no output on the watt meter. After checking some wires and scratching my head for a minute, I noticed that looking into the hole in the front of the amplifier where the band switch was removed from, there was no light inside the amplifier. The high voltage was good, so that tells me that I lost filament voltage to the tube. I have not opened the amplifier yet, but I am pretty sure that I got the amp too hot and melted the solder off of the filament pins ( a common issue). I will reflow the solder and should have the amp back online with no other issues.
There were no other casualties, and the contest ended well. barely pulling my my 101st contact with less than a minute to spare. I was thrilled to finally break the 100 contact barrier. Being down in a valley in Utah, we don’t get the big openings like the guys in the mid west do, so I am really dependent on 6 meters to open up to have any luck at all in the contest. When all is said and done, I enjoyed the contest, I am happy with the end result, and now I have a few more items that I know I need to work on.