[1000mp] Mark V Class A operation

[Rob Atkinson, K5UJ]

I am not an expert.  I have heard of people frying the pa in class a
operation.
A friend of mine and I tried class a and the heat sink got hotter than we
felt
comfortable with so we abandoned it.  I have heard of people blowing the pa
when cranking the collector current pot (power pot on the front panel) all
the way
clockwise and yacking away in class ab.  I have always run mine a little
below that.

Now you know where I was a few weeks ago.  I (or maybe it was someone else)
asked
something related to this on the yahoo group for yaesu and a guy who seemed
to be
very knowledgable about RF design said that in class A, you actually do more
damage
running at low power, and you stand a bigger chance of frying
the pa if you dial back the watts in class A, which was what we had done,
thinking less
watts, less heat.  We noticed that running the rig in class A at 30 watts or
so didn't make a
difference; it still got real hot.  Besides, for me, that would not help
because my amp needs
at least 75 w. to be driven as it is not one of these ceramic tube screen
driven amps.

he seemed to think it should be run at 75 watts.  i did not understand
it and it is a paradox of class A I guess, and decided to stay with AB to be
safe.
if I can find his explanation I will try to send it.

rob/k5uj




----- Original Message -----
From: "Jim" <pywacker at fuse.net>
To: <1000mp at mailman.qth.net>
Sent: Saturday, August 28, 2004 12:28 PM
Subject: [1000mp] Mark V Class A operation


> I have heard some hams on the air (just a few) along with some limited
> posting on some boards about the use of the class A feature of the Mark V
> contributing to the loss of finals in these rigs. Any real truth to this
> statement?
>
>
>
> Thanks, Jim
>
>
>
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