[TenTec] Scout frequency jumping, Enough!

[Larry Kayser]

Greetings All:

This memo is to those who persist in trying to make a problem out of the
Scout's occasional propensity to change frequency under program control of
the internal microprocessor.  The microprocessor has the job of stabilising
the analogue VFO in this radio.

In the last few weeks several amateurs have opinioned on this forum and
other forums that the Scout is getting a bad rap, the so called "frequency
jumping" is not a real problem.  My intention in this memo is to carry this
issue one step further, to categorise the blame for the problem into two
piles.  The first pile is the tiny minority of radios that actually have a
problem and need to be sent to the factory for service.  (see the PS below)
The second pile, and the vast majority of all the discussion here on this
forum and in other forms is the result of using the radio in a way that is
less than optimum and results in the radio responding by jumping around.

I have a Scout.  I use it both mobile, fixed, and portable.  When someone
says it is jumping around I know immediately that I am doing something
wrong.  I know that I have RF feedback or I have a power supply with a
higher than acceptable internal resistance or I have a power cable that has
higher than acceptable internal resistance.  I can also tell that when I
operate the radio in a physically challenging condition, bouncing around on
the front seat, or in a temperature challenging environment, -25C in the
winter and the heater on full blast, that I am asking more of the radio that
I have a right to.   I also know that if the Radio is jumping around I have
done something wrong, I have a job to do to fix it, and when I have it fixed
I will not have a jumping around problem anymore.

On this forum in the last three years I have found over a dozen different
references to frequency jumping that was resolved by fixing a problem
outside of the radio.

If you have a frequency jumping problem remember that it is a 95% chance
that you are doing something wrong and further that you are broadcasting far
and wide that you do not know how to solve your problem!  The radio for 95%
of the time is telling you that there is a problem that needs fixing, only
approximately 5% of the time is the radio the problem maybe.

Now lets talk about the one place were the radio has a design issue that can
not be overcome without some consideration by the operator.  If you are
operating CW at and over 30 WPM you must supply a .5 to 1 second time
interval from time to time for the microprocessor to get a reading of the
VFO frequency and apply the correction to the VFO.   The VFO is doing what
all analogue VFO's do, it is wandering along moving its frequency at some
rate per unit of time.  The microprocessor needs to measure the VFO
frequency, check what frequency the VFO was last moved to and then apply a
correction voltage to the VFO so that the frequency does not jump to the
next increment of change for the VFO.  What is the "time to time interval"?
I sense for a Scout operating in a non physically and non temperature
challenging environment it is every 20 to 30 seconds at a minimum.

If you do not want to allow for the 1 second update interval buy a different
radio.  You will not get a radio with the low internal noise and the price
of the Scout that will meet such a requirement.  The lower price is the way
that Ten Tec found to not have to individually tune up the VFO's with
temperature compensating capacitors like they do for their other analogue
PTO's.

Remember, when you complain about the Scout jumping around your really
displaying your inability to deal with your problem - you might not like the
message, but you now know plainly what your peers think when they see the
ongoing noise about this radio, 95% of the time.

Larry
VA3LK

PS  How does one know if a Scout VFO needs service?  This is an area that
the factory could have put more attention to in my opinion.  The information
you need is at what rate is the VFO drifting and how often is the
microprocessor having to apply a correction to the radio to keep it on the
frequency it is set to.  It would be ideal to have some indication from the
radio as to what the rate of change of the VFO and the corrections applied
by the mircroprocessor are.  This would help the user understand the
performance of the radio and become part of the solution rather than a lack
of information encouraging the user to become part of a perceived problem.
This is a design philosophy issue that Ten Tec should not be expected to
discuss in public.


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