I beg to differ on the matter of neutralisation.
There are different ways this can be achieved, but true neutralisation can
be redrawn as a bridge circuit which is frequency independent.
Classic texts all show this.
Classic amps hold neutralisation over a frequency range of several octaves.
73
end
Barry Kirkwood PhD ZL1DD
Signal Hill Homestay
66 Cory Road
Palm Beach
Waiheke Island 1240
NEW ZEALAND
www.waiheke.co.nz/signal.htm
----- Original Message -----
From: Richard <2@mail.vcnet.com>
To: <g0ruz@btinternet.com>; AMPS <amps@contesting.com>
Sent: Tuesday, April 09, 2002 1:12 AM
Subject: Re: [Amps] tuning tetrode amplifiers correctly
>I know that this subject has been visited a few times but how exactly
should
>you tune a large tetrode amplifier. Adjust the loading to get the correct
>value of screen current, then peak the screen current with the tune C and
>back off the drive so that the recommended screen current is restored. Is
>that about it? I have been running triodes for a long while now. I would
>appreciate a step by step approach.
>
? With an adjustable output driver and with no anode or screen V:
1. Apply expected drive level and adjust the grid's variable inductor
for zero reflected P.
2. Adjust grid-bias V for <0.05mA grid current.
3. Remove drive.
4. Apply anode and screen V. Adjust screen V to the rated max.
5. Apply drive and tune/load tank for a peak at the mfg's rated screen
current.
6. Add readings and freq. to the tuning reference list.
Notes -- For ultra linear Class-A operation, back off the mic gain until
the anode current does not rise during modulation. // Since
neutralization only works at the frequency of operation [Step 1], the
grid must be terminated with a resistance unless you are trying to build
a VHF oscillator.
cheers, Conrad
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
end
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