Mark said:
" So, it would seem adjusting the mic gain with full output would be more
accurate for psk31 (or other data) work."
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As was indicated earlier, a major issue with PSK31 transmissions is
"self-inflicted" IMD (Intermodulation
Distortion). Significant IMD (Created at the transmission point) can make an
otherwise strong signal difficult or impossible to copy. Consequently, you
really don't want the output power level of the Orion anywhere near the ALC
trigger point. The Orion power set adjustment on the front panel sets the ALC
trigger point. Therefore, setting that level high - as in 100W - and then
adjusting the audio signal drive level to something like 25W output on the
Orion will ensure that the Orion is operating at a very linear point of
operation (No ALC action is even close to occurring) and the PA has plenty of
headroom - of course no signal processing on.
Another very useful meter facility for PSK31 is PSKMeter
http://www.ssiserver.com/info/pskmeter/ . This allows "measurement" of the
transmission envelope on idle. You can see the waveform, against a correct
pattern overlay, and automatically measure the IMD. This allows you to use
higher power levels for DX but still insure the IMD level is very low. This is
the kind of capability that would be "a natural" for the Orion and its signal
processing and display facilities. Even with the growth in popularity of new
digital modes, today's transceivers are essentially "without tools" to
correctly set signal levels. Maybe in a future release of the V2 firmware :-)
73, Merle - W0EWM
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