To: <tentec@contesting.com>
Date: Tue, 24 Oct 2000 20:31:14 -0700
From: "Peter G. Juliano" <jessystems@waypt.com>
Subject: [TenTec] Model 544 Frequency Hopping
Hi Ten Tec Users,
I recently acquired a model 544 Ten Tec Triton IV--and for about a week
it
has been working perfectly. Then this evening I noticed that the
frequency
display was jumping all over the place--it was not just a display
problem
but the frequency was moving too! The worst case is on 20 M where the
VFO
feeds the mixers directly. The frequency jump can be as much a 1 Khz. It
is
random too! Once it moves it continues to do so. Sort of like the one of
the
first VFO's I built.
I suspect a voltage regulation problem. The regulator board has a 723
regulator that is set for about 8.0 volts and this powers the VFO--but
there
is no adjust ment--( to see if raising the voltage would cure the
problem).
Any one out there seen this problem before?
I will call TT in the morning but thought some one here on the reflector
"has been there, done that"
Thanks
Pete W6JFR
Whenever I've seen problems with a 540 series or Omni like this
it's been due to one of the following:
1. The PTO needs to be rebuilt - easy to do yourself with a $20 kit from
Ten-tec.
2. The band switch has a dirty contact.
3. One of oscillators, probably the carrier/bfo, is simply jumping.
Best bet is to put a frequency counter on the PTO output
and then on the output of the other oscillators/mixers.
A good counter would allow you to troubleshoot this in an
hour or less.
I doubt that the 723 voltage regulator is going bad.
They tend to fail totally or work fine.
In any event, monitoring the regulator circuit output
with a digital voltmeter should show any instability.
73,
Doug/WA1TUT
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