[Amps] Henry 2k-4 HV inductor

Gary Schafer garyschafer at largeriver.net
Tue Dec 12 21:11:09 EST 2017

Be careful of changing the inductance. I am not real familiar with the Henry
amp but you seem to indicate that there is a small capacitor in parallel
with the choke that would indicate that it is a tuned choke.

If it is a tuned choke you will want to have the same value as the original.
The choke would be tuned to 120 Hz. 

Gary  K4FMX

> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Elliott L
> Sent: Tuesday, December 12, 2017 2:52 PM
> To: amps at 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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