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[AMPS] FT100D driving Alpha 87a

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Subject: [AMPS] FT100D driving Alpha 87a
From: (Curt Terwilliger)
Date: Thu, 26 Jul 2001 18:00:06 -0700
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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