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Author Topic: Henry 2KD Classic  (Read 1538 times)
AB8BC
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« on: November 13, 2008, 09:36:16 AM »

I have a Henry 2KD Classic that has lower than expected HV at idle (about 1700V CW/2600V SSB).  Previously I would have 2100/3100V.  My biggest issue to date is, when keyed to transmit, HV meter drops and shows no HV at all and Plate Current meter shows about 300ma.  No Grid current.  Unkeying exciter, the amp goes back to display 1700V on CW.  Both tubes light.

What I drive in (example 10 watts drive from a TS940) results in 10 watts out.  No amplification.

I have replaced one tube that was dark with one that I believe to be good (current state of operation).  Before I replaced the dark tube, I switched sockets to be sure the dead one was really dead.  It was in fact, but the curious thing (to me) was that it still showed 1700V (on CW) at idle.  So with one good tube in either socket, resulted the same HV according to the meter.

I am a bit puzzled here and any help would be appreciated.  Thanks and 73--  Kirk  AB8BC
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WB2WIK
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« Reply #1 on: November 13, 2008, 09:59:36 AM »

>Henry 2KD Classic       Reply
by AB8BC on November 13, 2008    Mail this to a friend!
I have a Henry 2KD Classic that has lower than expected HV at idle (about 1700V CW/2600V SSB). Previously I would have 2100/3100V.

My biggest issue to date is, when keyed to transmit, HV meter drops and shows no HV at all and Plate Current meter shows about 300ma. No Grid current. Unkeying exciter, the amp goes back to display 1700V on CW. Both tubes light.<

::Something is introducing a lot of resistance in the HV circuit where there shouldn't be.  "No HV at all" is a hell of a lot of voltage drop occurring somewhere.  Maybe the HV choke is open?  Or one branch of the HV rectifier?  The Henrys didn't use doublers, as many amps do.

>What I drive in (example 10 watts drive from a TS940) results in 10 watts out. No amplification.

I have replaced one tube that was dark with one that I believe to be good (current state of operation). Before I replaced the dark tube, I switched sockets to be sure the dead one was really dead. It was in fact, but the curious thing (to me) was that it still showed 1700V (on CW) at idle. So with one good tube in either socket, resulted the same HV according to the meter.<

::Well a "dead" tube, unless it's shorted, wouldn't change the HV in any way.  If the filament's burned out, the dead tube does nothing; it might as well be a piece of plywood plugged into the socket.  But it won't impact the high voltage.

Sounds like a power supply problem, needs to be debugged methodically.  If you're not comfortable working on live high voltage (and obviously lethal) circuits, you might ask someone who is to help you.

WB2WIK/6
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