[TenTec] TX EQ = -14 dB for PSK31

[Merle Bone]

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