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Icom 751A & Ten Tec Hercules 444

To: <tentec@contesting.com>
Subject: Icom 751A & Ten Tec Hercules 444
From: zettel@homer.libby.org (Steve Zettel)
Date: Wed, 12 Feb 1997 15:25:51 -0700
>I am trying to use my IC-751A and Hercules 444  but they do not seem to
>get along together.After doing what the manual says for both Icom
>and Ten Tec doesn't work.After correct hookups and running 35 watts of
>drive, Hercules amp trips out and status light over drive comes on.
>Does this with 10 watts also.SSB,VOX and CW mode.This is how I have
>it connected.
>          (1) outside antenna to amp marked antenna.
>          (2) amp marked transciver to 751A output.
>          (3) ten tec relay line to icom relay
>                 this should be the T/R line
>          (4) alc to alc   (5) then grounded
>this is all it list for operation.Any ideas would sure help.
>                                           thanks
>                                              73s/mr


Is this a new (first time) use of the Hercules? The reason I ask is that I
recently sold a Hercules II to another ham and he was getting overdrive
lights and poor power out with his Omni VI; I had been driving it with MY
Omni VI and had had no such problems. We were stumped until we discovered
that I had been using the brute-strength Ten Tec power supply or a marine
deep-cycle battery to power the Herc, and he was using a large mil-surplus
DC power supply. When he tried a battery, the problem disappeared.
Evidently, the Hercules is very sensitive to power-supply regulation and
requires a "stiff" or highly regulated supply with very little "droop".

The other possibility is a large,leading-edge spike on the output waveform
of the Icom. It is not unusual for solid-state gear to have a large
transient on the leading edge of the first or "keydown" signal. For most
tube amplifiers (excepting some of the Alphas), this presents no immediate
problem, but transistorized amps can and do react quickly to what they see
as an overdrive condition. In some cases, this CAN damage the amp if left

Hope this helps,

Steve Zettel  KJ7CH

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