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Old 11th Apr 2012, 10:48 am   #15
Roger ZS1J
Retired Dormant Member
 
Join Date: Mar 2012
Location: Plettenberg Bay, South Africa.
Posts: 30
Default Re: Valve Linear Amplifier project

Way back in the early 60s I made an HF Linear amplifier using a 7094 Tube in passive grid. Thinking about it today with more experience I think that going passive grid was messy. You needed a dummy load to dump much of the driving power and also the 7094 required a stabilised HT voltage which was done with a dropping resistor from the EHT and some OA2s and and OB2. The efficiency was quite good as the 7094 was rated at full power up to 60 mHz. 30 watt drive would give a good 300 watts out.

Just out of interest I built a G2DAF design linear much later but was very disappointed with its performance and also very messy using the 6X4 (I think) as the rf rectifiers to power the screen grids. Eventually I modified it to GG and what a difference. Worked an all bands.

Still think you are going the wrong route with 807s. They are much better when used in class C.

73
Roger ZS1J is offline