[Milsurplus] Calling All Smart People: "To Drive or Not To Drive?"

[Kenneth G. Gordon]

On 26 Apr 2016 at 9:10, David Stinson wrote:

> I can still drive the transmitter only to about 
> half rated output and the PA grid current is 
> very low compared to an xtal.
> To be fair, I think my buffer's output inductor
> is faulty and I'm replacing it.
> But here's the question:
> Why is driving the ARC-5 stage so much 
> easier than driving the BC-669 stage?

Well, first of all, IMHO, ARC engineers were better than Halli's.

Secondly, L-315 and bias voltage is lower or closer to Class B, requiring reduced drive. 

It seems to me that the 6L6 stage is more heavily biased towards Class C, therefore 
requiring more drive. This does, of course, contribute to stability, the 6L6 being a 
single-ended tube, but it makes the tube harder to drive.

But I could be wrong.

Anyway, 7 - 15 V of drive should be enough for anyone.

I have never cared for direct resistance DC feed to a grid in an oscillator stage, much 
preferring an RF choke to keep any RF voltage at the grid where it belongs. This is probably 
a small thing, but it makes me happier. Belt-and-suspenders, and all that.

Ken