Variable gain preamp anyone?

Tom Crosbie G6PZZ

I have always been aware of overloading receivers since my first comms RX, a Drake SSR1.

I think that any RF “gain” control should also include a degree of attenuation in its range.

Chris, I’m wondering how effective a variable voltage PSU (say 0-15V range) will be with the new + amp?

Experiments with a cheap Chinese amp module and variable DC supply kit proved less than successful. I think mainly due to the stability (or lack of!) of the supply.

I was hoping the voltage display could give some correlation to gain. The PSU used an LM317 but the 5k pot was a very course adjuster.

I’m trying again with an LT1083 which is quite a high current device but I’ve bought some 10 turn pots, looking for finer control of the voltage adjustment.

Looking for inspiration, ideas or being told I’m mad…





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