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Re: [Amps] Cold neutralization with high voltage bias?

Subject: Re: [Amps] Cold neutralization with high voltage bias?
From: Guido Tedeschi <>
Date: Thu, 9 May 2019 19:53:19 +0200
List-post: <>
Hi Ron and thanks for the answer.

I know that the better method is neutralize for minimum feed through of the signal with no screen and plate voltage applied (also disconnecting only the heater voltage will work), but I was thinking on an easier prcocedure that can be made even without having to open the radio.

Is an high negative Bias voltage not enough to cutoff the tubes and allow a correct neutralization?

73 and thanks

Guido, ik2bcp

Il 09/05/2019 01:05, Ron Youvan ha scritto:
  Hi Guido Tedeschi:

  Is it possible to neutralize a grounded cathode tube PA for minimum output signal, if the Bias voltage is set to maximum available value (ex. -80V for
a pair of 6JS6C) and the drive is limited to less than few volts peak to
peak (just to leave the tube in cutoff area)?
This method would be simpler and better than the classic "neutralize for
maximum power with plate dip"...

  The only way I ever neutralized an amplifier is to warm up everything to normal operating temperature (possibly operated in to a test load) and feed in a small sample of the actual signal and remove the plate and screen (if any) voltage then adjust the neutralizing control/s until you minimize the feed through of the signal.  (usually by observing the output with a spectrum analyzer)

  I was in charge of maintaining many transmitters during my life.
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