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Re: [Amps] Question for the tetrode experts

To: Vic K2VCO <k2vco.vic@gmail.com>
Subject: Re: [Amps] Question for the tetrode experts
From: N1BUG <paul@n1bug.com>
Date: Fri, 08 Nov 2013 16:01:08 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Tuning is VERY touchy. You really have to have the loading right or the screen 
current is
excessive in either direction.

None of my 4CX1000A or 4CX1500B amps were all that touchy, from 1.8 to 144 MHz. Screen current does vary with loading, from negative through zero to positive, but it is a smooth and easily controlled change provided the loading capacitor has some reasonable rate of adjustment. I prefer vacuum variables, but if using an air variable I put a vernier drive on it.

With vacuum variable tune and load caps in a pi network, I have no problem going from band to band by using logged presets. Of course the presets have to be changed if I make any change to the antenna system, and tuning needs to be verified if there is any possibility of weather conditions affecting the antenna (ice or snow).

73,
Paul N1BUG
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