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[AMPS] FT100D driving Alpha 87a

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Subject: [AMPS] FT100D driving Alpha 87a
From: (carl seyersdahl)
Date: Fri, 27 Jul 2001 18:11:33 -0400
I am not at all familiar with all the amps in opn. today, nor the many
exciters in opn. today, but it seems to me that many amps can be easily
overdriven by the many exciters on the market today. It would seem to me
that the mfrs. of both , should be aware of the situation and provide for
proper opn . of both.!! IE: provide for power control on the exciters and
provide for control of excessive drive to the input of the amps. this ALC
business is , to my mind , nonsense. There are a number of amps in this area
operating happily , altho  not max. legal limit (or more)with no alc ckts.
There may be some operators who are not even aware that their amps alc ckts
aren't even connected . This I know because I "repaired" their amps and
added the "negative feedback" resistors and disconnected the alc input or
output ckts. this is according to Mr. measures original info on this
subject. negative feedback is a subject that , it seems, is not being
utilized to max advantage. This is just one old ham's opinion on the
    carl/ kz5ca
----- Original Message -----
From: "2" <>
To: <>; "AMPS" <>
Sent: Thursday, July 26, 2001 9:50 PM
Subject: Re: [AMPS] FT100D driving Alpha 87a

> >
> >I am using an FT1000D to drive an Alpha 87a, and am thinking of building
> >"DC ALC" circuit to throttle back the juice to 60-80W out whenever the
> >is in "Operate" mode (because otherwise one day in the heat of battle I
> >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
> >to reduce the power in the same manner as turning down the drive control
> >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
> >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
> >to take my chances with the reliability of an active circuit.
> /\  100w?  The average duty-cycle of SSB is 15% during transmit.
> >
> >.....
> good luck, Curt
> -  R. L. Measures, 805.386.3734,AG6K,
> end
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