[1000mp] MPV Driving Amp

[Garry Shapiro]

You have been lucky--and it depends upon the load you are driving.

I once guest-opped at a sizeable station owned by a good but eccentric
individual, now SK. He had an FT1000D and a homebrew 4-1000A GG amp with
untuned input. I had the tuner on, but the amp's input Z varied with drive,
and so varied when keyed. According to my host, the tuner went nuts tracking
this change on every character--I was QSK---and failed, resulting in a large
repair bill.

-----Original Message-----
From: 1000mp-bounces at mailman.qth.net
[mailto:1000mp-bounces at mailman.qth.net]On Behalf Of Win
Sent: Sunday, October 22, 2006 8:42 AM
To: 1000mp at mailman.qth.net
Subject: [1000mp] MPV Driving Amp


I have heard, or read on this list, that you should not drive an amplifier
with the tuner in line. I am sure that there is a good reason for this, but
I can not, for the life of me, figure out what is is.

Yesterday, when a DX station I needed appeared on 15 meters, I switchewd the
amp over and started tuning.  The SWR going into the amp was 2 to 1,
limiting my drive.  This is probably because of some mods I made in the amp.
In any case I turned on the tuner and matched to the amp, and made the
contact.

Correcting the problem with the amp is nothing more than adding a cap to the
input circuit the nexty time I am into it..  I still ponder, however,  why I
should not use the tuner into the amp.  I have done this before many times
with other rigs using passive external tuners.

Win
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