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[Amps] B&W Filament Choke Query

To: <amps@contesting.com>, <topband@contesting.com>
Subject: [Amps] B&W Filament Choke Query
From: "EP Swynar" <gswynar@durham.net>
Date: Sat, 3 Mar 2007 15:17:18 -0500
List-post: <mailto:amps@contesting.com>
Good Day All,

Mining "...ye olden junque boxxe" here has yielded an undocumented, 
pre-historic Barker & Williamson type "FC-30" encased filament choke --- I  
would be most appreciative if I might solicit some feedback from seasoned, 
experienced users of this device...

Specifically, the unit has TWO pairs of terminals at EACH END (four per end, 
grand total of eight). I show continuity between any two terminals only, i.e. 
any one terminal on the LH side, & its immediate opposite on the other...

Simple & logical enough, with two leads coming into it from a filament 
transformer, & two leads going out, to the tube's filaments --- but then why 
the extra four terminals, two per end? Is it because the "FC-30" is, in 
reality, a "dual" type "FC-15" filament choke, & in order to attain 30-amperes 
current capability, one must PARALLEL the terminals...?

Also, has anyone ever utilized one of these devices on a frequency band as low 
as 160-meters...? These things were manufactured back in the day when there was 
no real practical need of any kilowatt linear amplifiers on Topband, due to day 
time / night time power restrictions imposed by the old LORAN navigation 
system. Consequently, I wonder if this thing even has enough inductance on 
1.8-MHz to effectively do the job...?

Up until now, ALL of my filament chokes were of the homebrewed variety, i.e. 
heavy-guage enamelled wire coiled around a ferrite rod...I have no experience 
whatsoever with this particular pre-manufactured unit, I'm afraid...but I do 
harbour thoughts of employing it into a dedicated 160-meter-only grounded-grid 
RF amplifier, utilizing a 4-1000A (still to be acquired!).

Many thanks in advance, & my vy

~73~ Eddy VE3CUI - VE3XZ
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