I also had a choke fail in my 3KA. Gary ( another ham sent you his call)
rewound it for me and did a great job. It does need to be the same
inductance as Henry did use resonant chokes with a small capacitor in
parallel. Gary checked the inductance on my original to make sure it
matched. He also told me exactly how it failed (short of secondary to frame
but only at high voltage so needed a Hi-Pot tester to diagnose and confirmed
visually when disassembled. It blew through the cardboard bobbin to the
laminations. Gary used a modern plastic bobbin rated for the voltage.
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Elliott L
Sent: Tuesday, December 12, 2017 12:52 PM
To: amps@contesting.com
Subject: [Amps] Henry 2k-4 HV inductor
Hi All,
I recently purchased a Henry 2k-4 with a high-voltage fault. The fault has
been traced to the inductor, L201, which is located directly after the
bridge rectifier.
The value, according to the schematic (I have the same PDF that most of you
have, with K9ARZ's stamp on the cover) is 8 Henry, 700mA.
Peter Dahl lists a 2k-4 choke "exact replacement" part for this amplifier,
but the value is 10 Henry. I called up the company and they verified that
the manufacturing directions do indeed specify a 10 Henry choke, and also,
that their copy of the 2k-4 schematic shows the value should be 8 Henry.
So my questions is two-fold.
1. How critical is the value of this inductor to begin with? Is there some
intentional resonance with the parallel capacitor? Wouldn't the RF be fairly
snubbed out already from C49, C48, and L11? My intuition says that the value
is not super critical, and that 10 Henry is probably better than 8, all
things considered. Looking at the wiring at this DC stage, it doesn't look
like a high-tollarance tuned circuit.
2. The original part inside the amplifier has this writing on it: "14405
FERRODYNE 13821" Does anyone have a reference for what the intended value
actually is? Other Henry amplifiers in this line (2k-x, 2k-classic, etc)
have 8 Henry, so I am inclined to believe that 8 Henry is correct, but a
reference back to the original part would be pretty good evidence.
And more ancillary question, the original is rated for 700 mA. Would that
likely be intermittent or continuous?
Thanks very much (and great mailing list!),
--Elliott
W6EL
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