For the uninitiated, 52.525 MHz is the simplex calling frequency on six metres FM. Over the years I have built at least one 'homebrew' radio and modified a number of ex-commercial radios for myself and other hams. It's a time consuming process but I enjoyed the challenge. Below are some radios from the 1960's, 70's and 80's that were in common commercial use in Australia and often converted to six FM. Further down the page will be my latest homebrew efforts.
The first is an almost all-valve AWA model MR6. It would be 'all valve' except that it has some solid state rectifier diodes and two germanium PNP transistors in the DC to DC high tension supply. I have owned this radio since 1978 or there abouts. It produces around 10-12 Watts of RF on transmit and around 0.5 uV sensitivity on receive. I added a MOSFET RF preamplifier to the receiver a couple of years ago. Its biggest drawback is its wide bandwidth 2 MHz IF filter. These radios were used in the day when channel spacing was 50 KHz or greater in Australia. I had my first inster-state contact on this band using the AWA MR6 pictured below not long after it was modified for six in 1978. It was a great thrill talking so far on VHF!
Last updated on the 24th August 2020