[TenTec] re: Model 544 Frequency Hopping

[dslosty]

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

--
FAQ on WWW:               http://www.contesting.com/FAQ/tentec
Submissions:              tentec@contesting.com
Administrative requests:  tentec-REQUEST@contesting.com
Problems:                 owner-tentec@contesting.com