Some Scouts can benefit from having adjustments to the NPO type caps to set
minimal drift in CW mode. See the manual for why a PTO drifts in the Scout.
The computer can only correct it up to about 25 wpm code speed, unless you
pause periodically in sending, (which most folks would do anyway). That
gives time for the PTO to be corrected for any heat drift. Otherwise there
will be a step correction at first pause. If you adjust the NPO type
compensation to minimize drift from normal heating, you do not have to
correct the PTO as often.
Just adding a fan blowing on the heat sink when running 50 watts will help
the PTO stability some have found. I guess it keeps conducted heat from the
front of the radio here the PTO is.
Other mods are to place a pot for the fixed resistor that sets RF gain, and
to place an outside pot to adjust power, replacing the on board bottom
facing trimpot. Use of flat cable allows the 3 pot leads to be run out the
back of case between lid and back wall to a bracket mounted pot. Another
version makes the mike gain a fixed resistor and uses that 10 k pot to
replace the power pot.
If you mainly run SSB, you will not need to do anything to the PTO about
thermal (normal) drift of the LC circuit. The computer will correct. It
only comes up in CW because the computer also runs the keyer, and there is
not enough time at speeds above 25 wpm to do both. However, who runs 20
plus words per minute without pauses? I think it is more of a possible
concern than a real concern, as the instructions point out the simple fix,
pause in your sending.
73,
Stuart K5KVH
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