[Amps] plate choke values

[Roy]

Eddy asked,

"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...?

I know confusion can creep in in the form of the self-destruction of these 
parts if the hapless home brewer happens upon a band where there's 
self-resonance in the choke...but that issue aside, is this all some matter 
of "...by gosh & by golly black magic", or are there very real minimum 
standards & parameters that we should adhere to...? And if so, where are 
said standards published...?

I certainly can't find them via "...the usual" routes --- but again, I must 
be missing something here..."

~73~ Eddy VE3CUI

Eddy,

Minimum value is mainly the concern on 160M. A simple test can be performed 
with a dip meter coupled into the tank coil, while connecting and 
disconnecting your plate choke. A choke of ample inductance will hardly 
change the resonant frequency of the tank circuit at all. A too small value 
will reflect "negative reactance" into the tank, and that will be manifested 
as requiring more capacitance setting of C1 in the pi-net, a result of too 
much RF current flowing in the choke's winding. The best plate chokes are 
'invisible' to the tank circuit.

73,   Roy,   K6XK