Harris VHF Amp Rack Project – Welcome to Radio Station N1OFZ

I’ve been running my Harris channel 2 amp on 6M for a couple of years now. See here for details. I came across an offer from K5RUS who was selling Harris amps tuned up for 2M and 1.25M. He also made some very nice band pass filters. Needless to say it was a deal I could not pass up. I had a small UPS cabinet that was part of a Unisys computer system. That looks perfect for this project. I need to move some shelves around and do a bunch of wiring but in the end I think this will be a neat rack of 1000W VHF amplifiers.

When TV went digital all the analog amps were retired. These Harris amps are perfect to convert for ham use. I now have a channel 2 amp (54-60 MHz) on 6M, a channel 7 amp for 2M (174-180 MHz) and a channel 11 amp (198-204 MHz) for 1.25M. They have all been tuned up to operate on the ham bands. I’ve included some links below on the conversion process. Below are pics of the amplifiers.

Once the signal comes out the amplifier it needs to be cleaned up. So the next step is to send it through a low pass filter which suppresses any harmonics generated by the amplification process. It’s important to have a clean signal. The FCC states in part 47 CFR § 97.307 – Emission standards: The mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency between 30–225 MHz must be at least 60 dB below the mean power of the fundamental. So for the two new amps K5RUS built some beautiful low pass filters.

As you can see these filters will clean the signal up nicely. Then it heads to the my SWR monitoring system. I have a WaveNode WN-2 that can monitor up to 4 signals simultaneously. I currently have a HF-1 sensor that handles up to 2000W and covers HF to 60 MHz. This will be on the 6M amp. My UHF-1 sensor that would cover these bands but it’s only good up to 300W. I need a second one anyway so I’ve ordered the UHF-2KW and UHF-220 MHz sensors.

The WaveNode has been excellent, the only thing I wish it did was work with a Mac. The mfg has given me information as to how to write my own software and I hope to add this to my project list in the future. For now I have a Windows machine that use just for the WN-2. Of course I don’t need a computer at all as the WN-2 has a display itself. It’s just nice to see the status of all the amps at once on the station computer.