Scout Anomalies

20 May 1996 10:52:59 -0500

A jump in frequency and 200 Hz backlash sound like non normal operating
problems.  They are not in agreement with what Ten Tec describes as the normal
correction of the PTO.  One of the major points is that you have to pause in
sending, to allow the micro to take on the PTO correction instead of keying
duties.  Why do some send such long fast code strings without a break or
pause?  That 

Instead of just complaining, to the list, I would urge anyone who actually has
the jump in frequency to write up a detailed description, including at what
code speed, (Timed, not estimated), and if possible record a short cassette
tape of it and send to Ten Tec Service.  I think there may be a way they can
help you.  One thing that comes to mind is the variability in microprocessor
clock frequencies.

Of course a faster Microprocessor should process all duties better than one
running on the slow edge of normal.  Many cheap microprocessors can get into
clock problems.  This can be a cheap crystal, that has a range of tolerance. 
If one PC has a slightly different clock from another, it is not so noticeable
unless the two are side by side doing the same task.  Yet, when a time
critical interrupt task such as the keyer funtions take more of the total time
and do not allow the PTO correction, one can exceed the design range of the
manufacturer.  One obvious solution would be to run an external keyer into the
manual key jack, leaving the internal micro to control PTO alone.

Mechanical tuning is just that, mechanical.  Each has their own preferences as
to touch, feel, and tolerance for resistance to turning.  But, there should be
some adjustment available for those PTO's exhibiting backlash.  Perhaps some
on the list who have rebuilt the older model Ten Tec PTO's can comment if
there were aspects that allowed adjustment of backlash?  Of course, the best
resort would be a phone call to Ten Tec Service.  Or a detailed letter,
carefully  describing all aspects of your use that produce less than desired
-73, Stuart K5KVH