That's been my experience, too. Once when operating portable, it took a
major frequency shift on SSB. I traced the problem to a corroded crimp
lug where the power cable connected to the SUV battery. Too much voltage
drop.
The voltage regulator is a low differential type, whatever they are
called. There are some helpful tricks that you can do to minimize
voltage drop, like tightening the pins on the power connectors and
replacing the spring-loaded fuse holder with an automotive blade type.
Fixes applied directly to the PTO are shortening the coil leads where
they connect to the PC board, to minimize vibration effects, and
replacing one of the 15 pf N750 caps with an NP0 type, because some
Scouts are overcompensated.
There is one software quirk that I noticed. If I transmit on CW, then
immediately flip the toggle to the "speed" position, the PTO will take
off. Not something one would normally do, and definitely a software
issue, I think.
On SSB, my Scout seems to sound best with a dynamic mike instead of an
electret type.
73,
Bob WB2VUF
Stuart Rohre wrote:
> I have always had good reports on SSB on my Scout.
>
> The drift problem was a non problem if hams just read the manual and
> were not CW speed addicts. I never could send as fast as they said it
> caused the CW problem so a non issue here.
>
> I did find that Scouts don't like to run a battery that is only capable
> of 11 volts, one year at Field Day. Then, it did drift on SSB, but it
> was entirely the fault of the discharged battery. Putting a fully
> charged one on the rig fixed everything. The limit was because of the
> input to output differential needed by the model voltage regulator
> chip. Most standard ones need a 2 volt differential or so. I was going
> to see if a low drop out regulator could be found to fit the board, but
> never got time to pursue that mod. There were some capacitor changes
> that improved the CW issue, at high speeds. They are in the archives of
> QRP-L reflector, if not also in Ten Tec list archives.
>
> 73,
> Stuart
> K5KVH
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|