The 87a should shut off if you over-dive it. Let the amplifier safety
circuits take care of the problem.
Although and ALC circuit just in case is a good idea. I would not rely on it
for everyday use. It most likely result in splattering.
73 and good luck
Jim W7RY
----- Original Message -----
From: "Curt Terwilliger" <ki6j@hotmail.com>
To: <amps@contesting.com>
Sent: Thursday, July 26, 2001 6:00 PM
Subject: [AMPS] FT100D driving Alpha 87a
>
> I am using an FT1000D to drive an Alpha 87a, and am thinking of building a
> "DC ALC" circuit to throttle back the juice to 60-80W out whenever the amp
> is in "Operate" mode (because otherwise one day in the heat of battle I
will
> forget to reduce the drive power manually and probably cook the 3CX800s).
>
> This would not be RF derived ALC, just a DC voltage applied in steady
state
> to reduce the power in the same manner as turning down the drive control
on
> the front panel.
>
> AG6K, to whom I earlier mentioned this plan, has observed that using
> suitable cathode resistors might be a more simple and reliable way to
allow
> the Alpha to accept a full 200W of drive. Point taken, although I am not
> keen on adding 100W of dissipation to the cathode compartment and am
willing
> to take my chances with the reliability of an active circuit.
>
> I was wondering what others think about this DC ALC approach, and if
anyone
> is currently using it?
>
> Tnx es 73,
>
> Curt W6XJ
>
>
>
>
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