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Re: [Amps] 813 "Flimimate" Choke

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Subject: Re: [Amps] 813 "Flimimate" Choke
From: "AA6DX - Mark" <>
Date: Sun, 4 Mar 2007 11:51:37 -0800
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More on the days of yore--
My first home-brew amp was a pair of 813s, GG .. cheap and dirty, as it was 
called back when .. no tuned input.  The GG filament choke was wound on a 
pencil, using fabric insulated wire ... worky worky for DXCC!  I cannot 
remember the turns, etc... was 42 years ago .. HIHI.  Got another one of 
those pink slips from the Franklin Candy Company with this when working 
split DX on 40M SSB-- too close to the band edge with the HT-37 phasing 
rig's mike gain cranked up, along with the non-tuned up input on the amp .. 
but, whatta heck, I was working EUs with a 40M dipole!  HIHI..
Also .. Dentron amps infamous for desoldering themselves in important places 
.. if yours quits worky worky, check the large solder joints FIRST .. 73
Mark Nelson  -  AA6DX


Message: 1
Date: Sun, 4 Mar 2007 00:49:15 EST
Subject: Re: [Amps] Old POwer Cord
Message-ID: <>
Content-Type: text/plain; charset="US-ASCII"

Kim, Dentron is noted for the poor wire used on it's power cords.  I  have
had to replace several cords on Dentron amps in the past.  Your not  alone.
Good luck with the amp. 73 Lou
> Kim, Dentron is noted for the poor wire used on it's power cords.

It's not just Dentron.  I had to replace one on an Alpha amp
recently.  OK, it's an OLD alpha amp (70V) but the black wire in the
cord was crunchy the whole length.  The white and green were OK.

Moral : check the power cord from time to time.


George T. Daughters, K6GT

Good Morning All...

...And many thanks to the SEVEN respondents who took the time to address my 
query yesterday re. the whys & wherefores of my old Barker & Williamson type 
"FC-30" filament choke...

For benefit of any interested parties who may one day chance across one of 
these assemblies at a Hamfest, etc., here's what I learned on the PLUS side 
(file it away on the back-burner --- it may prove to be useful at some 

-The FC-30 is, in essence, TWO type FC-15 filament chokes in ONE enclosure;

-Each of these FC-15 chokes is rated at 15-amperes: to safely pass 
30-amperes through them, you simply parallel the two, and,

-The unit has the flexibility of feeding two separate tubes from two 
separate filament transformers via its two separate chokes (maximum 
15-amperes per filament, of course), or, one tube / paralleled tubes 
requiring 30-amperes maximum.

Now, on the MINUS side:

-The FC-30 is specified for operation from 3.5-MHz to 30-MHz, inclusive: 
because each FC-15 rod is only 3-1/2" long, it does not have enough 
inductance for 160-meters;

-Even if I elected to SERIES-connect the two interior FC-15's to secure 
twice the inductance for possible use on Topband, I would be robbing it of 
its ability to handle 30-amperes of filament current...and my hoped-for 
4-1000A requires 21-amperes to make it glow (sigh!).

I've always been curious as to the possible effectiveness of employing the 
ferrite core from a TV picture tube deflection yoke / coil assembly as the 
foundation for a robust torroid-type filament choke...I have an inordinately 
LARGE example of one here, which was removed from a junked early colour TV 
set many years ago: maybe this is an opportunity in disguise, waiting to be 

I have no knowledge of anyone ever having tried this latter trick, but I 
can't see why it wouldn't work.

~73~ Eddy VE3CUI - VE3XZ


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