-----Original Message-----
From: measures <2@vc.net>
To: AMPS <amps@contesting.com>
To: <amps@contesting.com>
Date: 25 March 2000 11:54
Subject: [AMPS] Is screen potential important?
>
>In a G2DAF amplifier, screen potential wanders from zero to approx. max.
It doesn't wander. It follows the rf envelope.
>Some say that screen potential can wander about with no serious
>consequences. Please consider the constant-current curves for the 8171
>posted at the beginning of my Web site. One set of curves is for a
>screen potential of 500v. The other set is for 1500v on the screen.
>Assuming a peak grid potential of +10v, with1500v on the screen, peak
>anode current is c. 12a. However, with +10v on the grid and 500v on the
>screen, .peak anode current is 3a.
But screen voltage is set by rf (=grid) voltage. If +10 grid gives +1500
screen it won't suddenly or randomly give 500V screen instead. The time
constant in the screen system is in the order of usecs, the fastest edge in
a SSB signal is in the order of 100us - to all intents and purposes, the
screen will follow the rf envelope.
I don't think you could get +10 grid and 500 screen at the same time with a
normal SSB drive signal.
Steve
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