[Amps] 4CX1500 class AB1 vs. AB2

[Peter Chadwick]

Tom said:
>As a matter of fact, I'd never consider it a good idea.<
That makes two of us then, Tom.
Putting NFB on in a grounded cathode amp isn't that difficult - some resistance in the cathode - say 10 ohms - with a suitable RFC across it so the effective bias doesn't vary has a very useful effect. I got about 12dB improvement in 3rd order products from that in my AB2 pair of 4-250As. But I do use a shunt regulated bias supply and a regulated screen supply, as well as about 200 ohms of grid shunt resistance for the RF load - my driver is an FT102, so the SWR doesn't worry it.
73
Peter G3RZP