-----Original Message-----
From: Chris Tran GM3WOJ <gm3woj@talk21.com>
To: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: 07 September 2000 18:17
Subject: [AMPS] 4CX1000A grid current
>
>Hello all
>
>This reflector is getting busy ! Difficult to get a word in on
>the frequency !
>
>I have a homebrew 4CX1000A amplifier (passive grid,
>grounded cathode) and over the past few months the
>grid current meter (control grid) has started to read off
>the scale in a negative direction, about 1mA ?
>The reading slowly appears over 3 mins. as the cathode
>heats up.
I'm working from memory here. Some years ago there was a RadCom article of a
hf amp using (I think) 4CX1000. The author mentioned seeing this effect in
some of a selection of valves he had. they all appeared to work ok in
practice. A friend saw the same in a 2m PA he built at the same time. It's
given him no problems, although it's not been overworked.
Steve
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