[Amps] New SB-200 owner

[Steve Thompson]

Peter Chadwick wrote:
> Steve said:
> 
>>I think they can do better linearity than that - the amps I built have 
> 
> all done so at 250-300W/tube. The STC data sheet for 4CX250B gives IMD 
> figures under the typical operating conditions. At 2kV, 325W pep output 
> they give IMD3 -30dBc and IMD5 -50dBc.<
> They can do even better with some negative feedback. The KWS1 (which didn't have feedback) claimed 35dB down, although they don't say if that's relative to PEP or to tone. That's at 1kW input, which would align with Steve's figures.
> But you need a screen supply, and from an economy viewpoint, that can be a trouble.
It needn't be. If you stay simple, a dropper from the anode supply with 
an uncomplicated active shunt regulator costs about a pack of beer. 
Regulation is more than adequate. I begrudge wasting 30W as heat, but it 
saves a transformer.

Steve