G4DCV GS31b 144MHz Amplifier/gs1-2.jpg

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If you do not understand high-voltage safety procedures do not attempt to build a tube amplifier.

The HT voltage will kill

The input circuit is used by YU1AW on his 144MHz triode amplifiers. I'm using 2 turns.

I also use this input circuit in my 2 x GI7b 144Mhz amplifier. The input SWR is 1:1. Since the photograph was taken I have replaced the lower variable capacitor with one of a smaller value (10pF).

The white pipe blows air from the anode compartment across the cathode. It is an electrical conduit elbow. Thanks to Ian, GM3SEK for the idea.