[Boatanchors] Grounded Grid filament choke spec's

[Carl]

There is no magic since some designers use a smaller choke and design the 
input network to compensate. The problem there is having enough bypass C at 
the transformer end and its still often a compromise on 160M that absorbs 
some power.

The old standby for a 25-30A choke was a 33 Mix ferrite rod 7 1/2" x 1/2" 
which is good 160-10M.

Carl
KM1H


----- Original Message ----- 
From: "Greg Mijal" <bluebirdtele at embarqmail.com>
To: <boatanchors at mailman.qth.net>
Cc: "Glowbugs" <glowbugs at piobaire.mines.uidaho.edu>
Sent: Thursday, June 04, 2009 5:34 PM
Subject: [Boatanchors] Grounded Grid filament choke spec's


> Hi:
> A couple of months ago the group discussed using filament chokes in 
> grounded grid amplifiers.  Someone mentioned that if you were planning to 
> use the amp on 160m a larger filament choke was required.
> So what's up with that? What's the magic number of uh's needed to decouple 
> a 160m driving signal?
> I measured a B&W FC 30 filament choke and it measured in the 7 - 10 uh 
> range for each wire. Am I ok using the FC 30 as is on 160m?
> Tnx
> Greg
> WA7LYO
> Kinston NC
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