[Amps] Plate Choke Values

[Vic K2VCO]

Eddy Swynar wrote:
> Good Morning All,
> 
> Am I missing something here...?
> 
> Extensive research here into years & years of ARRL HANDBOOKS, Bill Orr HANDBOOKS, and
> the internet have shed precious little light in the matter of optimum / minimum values
> of inductance for plate chokes in the B+ leads of our tube-type linear amplifiers.
> 
> Have a look-see yourself: in designs that feature amplifiers that only go as low as
> 3.5-MHz, you'll see chokes that range in value anywhere & everywhere from 200-uh, to
> 50-uh. On 160-meters, I've seen quoted values as high as 1.0-mh., and others as low as
> 200-uh.
> 
> Just what, exactly, is a "...minimum reactance" for a choke, on a given frequency band,
> to do its job effectively, anyway...?

This is a good question which I would like to know the answer to as well. My SB1000 makes 
less power on 160 than 80 or 40 meters; I am wondering if the choke is adequate.

Some years ago I had an older SB1000 in which I had installed an Ameritron choke (to avoid 
resonances in WARC bands). It didn't have this problem, so I'm suspicious.

Input circuits are tuned to 1:1 and the tuning/loading controls appear to be in the 
correct places when tuned up.

I'm going to open the amp up soon to do a lot of things, so I can check the inductance of 
the original choke.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco