----- Original Message -----
From: "Douglas Snowden" <Douglas.R.Snowden@noaa.gov>
To: <conrad.farlow@virgin.net>
Cc: <amps@contesting.com>
Sent: Tuesday, April 10, 2001 3:25 PM
Subject: Re: [AMPS] MLA2500 and screen voltage for 4CX800.
> OK Conrad - thanks for the feedback. I read what
> you just said, but I don't understand why the screen
> would have a problem. I vaguely remember seeing something
> like this on a web site. Was it the measures page/s?
> Of course, I guess if the plate voltage got very low, I
> could see a problem developing.
>
> Doug N4IJ
Hi Doug, if you read the Tech notes on the G3SEK page there is a technical
explanation but basically ANY variation in screen voltage will wreck the IMD
performance of a tetrode and thus produce socially unacceptable amounts of
splatter.When you drive an amp with a complex varying waveform such as SSB
the anode voltage will swing all over the place.Obviously if you are
deriving your screen voltage from here your regulation will suffer. If your
regulation suffers then so will other band users.
http://www.vcnet.com/measures/D.a.08.GIF is the circuit to use off Rich's
pages. He also has a stack of zeners off the plate supply on another
page.Please don't do this.
Regards
Conrad G0RUZ
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