First post from a new member and already asking questions.
Has anyone had any experiences "good or bad" with the Russian GI7B
tubes. Just chasing information for a club project a "single band amp"
for possibly 40 or 20.

Noel
VK4HR

Noel,

Please see this page for lots of links to both retrofits and homebrew amps using the GI-7B including one in progress by Bob,VK3ZL: <>

73, Tony W4ZT

vk4hr wrote:

Hi Noel

I built a 2m amplifier a couple of years ago using a pair of GI-7b triodes. It has been absolutely trouble free except for one flash over when I accidently grossly over-drove it. That took out the HT glitch resistor as well as the transformer primary fuse but both tubes survived and are still in operation. The amp has been used (and won) several 2m contests here in the UK and I regularly run it using WSJT which is a high duty cycle mode.

25 watts of drive gives me the UK legal limit of 400 watts out. The maximum I get out of this pair on 2m with about 1700V on them is 700 watts.

This amplifier is online at BTW I wouldn't have dared post that link in the old Amps group! I'd have been torn to shreds!! But I know in here any criticism will be helpful and positive.

The tubes only cost me UK 15.00 each including postage from Russia. It's difficult to beat that for low cost.

I'm thinking along similar lines to you now and may also build a HF RF deck. I wouldn't hesitate to use the same tubes again. Their slightly bigger brother the GI-46 is supposed to give more power out. It's a bit more expensive but would also be worth considering.

73 Paul G4DCV

vk4hr wrote:

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