[Amps] Fwd: Henry 1KD5 Reanimation

gudguyham at aol.com gudguyham at aol.com
Sun Aug 20 16:58:13 EDT 2017

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-----Original Message-----
From: gudguyham <gudguyham at aol.com>
To: k9mk <k9mk at flash.net>
Sent: Sun, Aug 20, 2017 04:57 PM
Subject: Re: [Amps] Henry 1KD5 Reanimation

<div id="AOLMsgPart_2_7ee89e13-e0d9-4fd5-a3e8-62304e7a2d5b">
<div class="aolReplacedBody">Mike, they aren't padder caps.  They are fixed caps that set the plate tune for each band and then the plate tune is finely adjusted with the variable inductor and the load adjusted as usual.  So you will have some degree of capacitance on each band unlike not having additional loading on each band as in a totally variable capacitance plate tune design.  Some models of Henry amps had ganged air variable capacitors for loading so that extra lumped capacitance was not needed.  Not sure off hand if that 1kd5 had the dual gang load caps.  

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-----Original Message-----
From: Mike & Becca Krzystyniak <<a href="mailto:k9mk at flash.net">k9mk at flash.net</a>>
To: amps <<a href="mailto:amps at contesting.com">amps at contesting.com</a>>
Sent: Sun, Aug 20, 2017 03:42 PM
Subject: [Amps] Henry 1KD5 Reanimation

Greetings All,

   This past week I recovered a Henry 1KD5 from an gargage sale/estate. 
   It appeared to be an 80M-15M model, that someone added 10M too.

   The amp looked clean so I brought it up slow with a variac.  Some initial
arcing from the HV wires which I quicky replaced.  
   However, up around the 3KV point I start hearing a steady hissing, with
some popping seen on the metering (Ip is flicking +/_ around zero).

   I can't be sure but it sounds like it is somewhere on the HV filter
board, the one that is mechanically holding the caps and bleaders.
   But nothing visible.  Are those boards a phenolic or bakelite or ???  
   Any hints on how to safely trace this down?

   The second issue is centered around the tube and tank.
   The is a Pi-L output and albeit an alleged design improvement, tuning to
get power out has been totally elleusive to the point I thought the 3-500Z
was bad.
   Looking at the cam shafted switched for the padder caps, I noticed that
the cam maybe off by one bandswitch step.

   Can someone tell me if all three of the plate tune padder caps are
"Switched in" on 80M, then 2 on 40M, and one on 20M?
   That is what the schematic suggests to me.  
   But this one has all three caps in on 80+40M, then 2 on 20M, and one on
15M.  It's like someone rotated the cams by one rotation indent.

   Back to the Pi-L tuning, does anyone have a better process for
setting/tuning a Pi-L tank (aside from the presets in the manual and web)?

Thanks in advance.

73  Mike K9MK/5    

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