I am working on a Henry 2KD Classic amp for a friend who has had a stroke and
can not tell me much it history. I want to get this fixed for him so he has
something to use in his condition. My friend told me that the grid current
meter vibrates very hard, and it does. He says that he has not made
modifications, but I am not sure of his memory and I have found some
differences from the manual. I fixed his power supply (was tripping circuit
breakers) and now have good High voltage and it has new caps in it (470 mfd at
500vdc), but have some metering issues and a resister (R109) that burnt out. I
replaced the resistor R109 25 ohm at 25 watt, only to have it burn out again.
It is then that I started to look more and found several differences from the
manual. If it were not for "the odd part" (see at bottom) I would chalk this up
as many miss-wiring. Miss-wiring can not explain all the issues. Too many odd
things going on without confirming some of the questions below.
Perhaps you could answer one or more of the following questions for me. Henry
2KD Amp. 2 * 3-500 tubes running 3200 vdc HV. Can anyone confirm or deny one
or more of the differences that I describe below? Even answering one or two of
these will help a lot.
1. R119 and D107 are Parallel in the book, but series in the amp (solder
looks factory, also parts are in control head). Was the book a miss-print or
what? Please confirm one way or the other.
2. R119 goes to HV (neg or low side) in the book, but in the amp it goes to
between R109 and D106.
3. D105 (Zener 100v) in the book, but is a 22.5k resister (note two 22.5k
resisters r113 and this replacement)
4. F101 is hooked between R109 and D106, your book shows that connection
should be on the other side of R109 (via R119 and D107) see question number 1
The odd part is that R119 and D107 is not in the power supply, but in the
control head. That suggest to me that the owner most likely did not mess with
this. Looks like factory soldering.
Other differences, but mostly interested in the top four. I thank you in
advance.
73, Bruce, w8hw@att.net
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