----- Original Message -----
From: "Rich..." <2@mail.vcnet.com>
To: "R_Davis" <WD8JJA@arrl.net>
Sent: Friday, February 15, 2002 9:18 AM
Subject: Re: [AMPS] AL811H on AM
>
>This brings up a question I have always had.
>
>We are always urged to tune for maximum power out at maximum drive. For
>SSB, I tune my FL-2100B (you guys already know this has 572B's) with 100
>watts drive
? Max drive for 2, 572Bs is c. 65W.
@@ OOPS - I believe that is 65 watts per tube, so at 100 watts drive, each
tube
gets 50 watts.
>at ~50 dots per minute (or whatever the max. of my keyer is) for
>maximum output, which is usually around 800 watts A0 into a dummy load.
>
>Now, for AM, RTTY, or some constant carrier mode, should the drive from the
>exciter be reduced without retouching up the tune/load controls?
>
? For AM, Yes. Even though the AM carrier is only 25% of PEP, the
loading will be right at 100% modulation peaks.
@@ Interesting perspective. I can see that point.
>I typically repeak the output of both transmitter and amplifier when I
>reduce the power. This gives more power output with less plate current.
The
>Plate control doesn't change much, but the Load reduces a lot when power is
>reduced.
>
? An amplifier needs to be tuned for the max PEP it will be used at.
@@ What about RTTY, SSTV, PSK31, etc where you drive it with audio from a
sound
card? I haven't actually use the amp for that yet, but the same principle
would apply to the sweep tubes in my transmitter. Would you peak the
plate/load for max out at the reduced drive or tune for max power at max
drive, then reduce power to a safe plate current. The power out will
definitely be less with more plate current. That sounds like a lot less
efficiency - wasted power in the tube - read HEAT.
Thanks for the reply and 73's.
Rick, WD8JJA.
>...
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
end
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