Amateur Radio Repeater

222.440/224.040 100 Hz PL

The Current Repeater

Currently, the repeater is a Bridgecom Systems BCR-220. I am using a used set of Wacom cavities and a Comet CX-333 antenna mounted at the peak of my roof in Los Alamos. For feedline, I am using some of the dreaded double shielded cable. The aluminum foil rubbing against the silver plated copper braid is supposed to cause noise. I have not noticed any problems yet.

Update 24 June 2018

I decided to replace my Hamtronics repeater with a Bridgecom machine. I have been very pleased with Bridgecom. The machine works well and the support from Bridgecom is first rate. They have answered all of my dumb questions without making me feel dumb.

Update 16 November 2010

While I did get the frequecy pair from the frequency coordinator, I was a bit slow actually filling out the paperwork for coordination. Well, it is now coordinated.

I am pleased with the coverage of the machine although it is not running full power. I need to retune the final amplifier sometime.

Update 26 April 2006

The crystals came and I installed them. While I was working on the machine, I managed to destroy the power transister that I had keying exciter. Now, the transmitter is running and I believe that it is on frequency. I have also tuned the duplexer to the best of my ability and equipment. The receiver is semi-tuned. It turns out that I didn't have all of the equipment that I needed to completely align the receiver. As a result, I have a used, ebay signal generator coming. With any luck, I should have the machine completely tuned in a couple of weeks.

Update 1 April 2006

This is the day that I was going to have the repeater up and operating. The good news is that the machine is working. It took me forever to get the final amplifier close to the specifications. I ended up adding 22pF in parallel with the 15pF fixed and 20pF variable capacitors to get the input impedence to 50 ohms. Then I had to remake the enclosure, because what I had changed the tuning of the amplifier.

I am still waiting on crystals to put the repeater on the proper pair. Currently, I'm sitting on 222.36/223.96. So, when the rocks show up, I'll have to tear into the repeater again and change crystals. Then, I'll attack the duplexer and IRLP connections.


At first, I didn't like the frequency pair 222.440/224.040. While it is 1.6 Meg apart, it goes from 222 to 224 and that sounds strange. However, I thought about it for a short time and realize a slightly odd pair was perfect for me. It matches my personality.

The repeater is located at my house in DM65uv.

The repeater is made up of Hamtronics components with the exception of the controller, duplexer and antenna.

The receiver is a Hamtronics R100 VHF receiver. I am running the crystal oven since I am using commercial power with battery backup.

The exciter is a Hamtronics TA51 VHF exciter. Again, I am running the crystal oven to maintain frequency stability.

The power amplifier is a Hamtronics LPA 3-15R.

WACOM model ?????? duplexer tuned by me. I suspect that it is not perfectly tuned.

The antenna is triband antenna mounted at the peak of my house.

During the rebuild of this repeater, great care was taken to double shield everything. The receiver, exciter and power amplifier are all contained within their respective tin boxes. All non RF connections go through feedthrough capacitors to exit the tin box. The tin boxes are mounted in a home made chassis partitioned to separate sections for receiver and transmitter components. Again, the non RF connections are run through another feedthrough capacitor as they exit the aluminum enclosure.

The contoller is mounted in an aluminum box that is separate from the repeater chassis. With this arrangment, I hope to be able to experiment with various controllers without tearing anything apart.