Hi Ed,
Thanks for the fast response! Yeah, both the original poster (Guy) and myself are using computer tuning of both radios. I know for sure my SatPC32 is set up for adjusting both the uplink and the downlink, and I see the readout on the radio changing accordingly, so it seems to be working ... what puzzles me is why the computer tuning seems to be so poor, since even though it's complex math, it's just math and the computer should be able to keep up!
Of course, since there are many on the list here using SatPC32 and twin radios successfully, I'm almost certain it's operator error that's causing this slight drift (or lack of complete correction), but I just can't figure out what it is yet. :-)
One thing I *did* notice with the Twin FT-817's, is that those radios (817,857, 897) do not update the TX frequency by CAT while they're transmitting ... so as I call CQ, I definitely hear my voice drop in pitch because the SatPC32 is busy updating the downlink frequency but the radio is busy so is not updating the uplink frequency. I accept that as normal (and just unkey to let the computer reset the radio for proper shift) but ...
... what's confusing me is that the amount of correction seems to change from pass to pass and even during the pass ... at first (out of the box) SatPC32 was about 2400 Hz low on the uplink based on the values in the doppler.sqf file. I just figured it could be due to radio calibration, etc, so I applied the calibration factor, and now it's much closer ... but still I seem to have to adjust +/- 100 to 200 Hz at the start of the pass, and periodically during the pass, to keep my return pitch constant.
Thanks everyone!
Dave KB5WIA CM88 Northern California.
When one gets up to modes like LS, it gets more challenging because both Doppler and rate of Doppler change are greater. Probably should consider computer tuning of the radio at this point.