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[AMPS] Re: [overshoes]

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Subject: [AMPS] Re: [overshoes]
From: gdaught6@leland.Stanford.EDU (George T. Daughters)
Date: Thu, 5 Jun 1997 14:14:08 +0008
hi tom,

you wrote

> I would too, if it worked properly. Unfortunately, those controls 
> more often than not allow the exciter to overshoot on leading edges.
> I've measured ICOMs that produce 300 watts PEP when set to 25 watts 
> output during the leading edge on SSB. My IC-706 hits 150 watts plus 
> on some bands (no matter what level I set the power control at), my 
> FT-757 hits nearly 180 watts, but my IC 751A is OK.
> A friends 950SDX snacks the PA with almost 300 watts on leading edges 
> with the power set at 100 watts. 
> The problem is the time constant in the internal power control system 
> (generally ALC derived from a directional coupler at the rigs 
> output) is slower than the rise time of the envelope.

this is a well-known (to some) problem... e.g. 87a owners who keep 
getting triggered off by these spikes.  and lots of transceivers are 
guilty of this it, by the way!!

putting an ALC in the amp isn't gonna cure it, because the rig 
obviously isn't quick enough to respond to the ALC signal!

oh, and make that "overshoot" in the subject line.


George T. Daughters, K6GT

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