20-03-2023, 02:03 PM
Recently, an old home-brew project of mine which I'd long forgotten about turned up at my local radio club (Geelong ARC) among donated "junk". It is a 6m transverter that I built over a weekend from accumulated parts from my then junk-box. This was in the early 1980's, hence my previous call sign, VK3BRZ, scribbled on it. At the time I had a TS-520S transceiver to use as a tunable IF, so it was a very simple matter to construct the transverter using mostly valves as the various voltages from the TS-520S internal power supply could be used to supply it.
The transverter lineup comprises the following:
Local Oscillator: 12AT7
TX Mixer: QQE03/12 in push-push configuration
TX Power Amp: QQE03/12
RX Amplifier: MPF131
RX Mixer: MPF???
Output power was about 10W, enough to drive a QQE06/40 PA that followed (I may have photos of that, too).
I don't recall the source of the brass enclosure. It is obviously home-brew, judging by the imprecise screw holes for the covers. Old-timers might be wondering why the PA stage is operated with the QQE03/12 twin tetrodes in parallel rather than push-pull. The answer is the enclosure was not large enough to fit the larger coils and split-stator capacitors necessary for the more common push-pull configuration. The eagle-eyed will spot the neutralisation trimmer among the circuitry.
It strikes me that so much old, home-brew gear just disappears as junk, and along with it, a part of Amateur Radio's history is lost.
Chas
VK3PY
The transverter lineup comprises the following:
Local Oscillator: 12AT7
TX Mixer: QQE03/12 in push-push configuration
TX Power Amp: QQE03/12
RX Amplifier: MPF131
RX Mixer: MPF???
Output power was about 10W, enough to drive a QQE06/40 PA that followed (I may have photos of that, too).
I don't recall the source of the brass enclosure. It is obviously home-brew, judging by the imprecise screw holes for the covers. Old-timers might be wondering why the PA stage is operated with the QQE03/12 twin tetrodes in parallel rather than push-pull. The answer is the enclosure was not large enough to fit the larger coils and split-stator capacitors necessary for the more common push-pull configuration. The eagle-eyed will spot the neutralisation trimmer among the circuitry.
It strikes me that so much old, home-brew gear just disappears as junk, and along with it, a part of Amateur Radio's history is lost.
Chas
VK3PY