[TenTec] Orion v2.056 PSK question

[Grant Youngman]

> really puzzled about the TX EQ setting though.  The Orion 
> manual suggests a setting of -14db.  This setting alone 
> changes the output more than anything else.  If I move it to 
> a setting of "0"  power drops to 5w output.  (PWR is set at
> 100) As I adjust the setting to -14db, the power increases to 
> 35w and will rise to 75w if I move it  further.  If I look at 
> the manual, this seems rather counter intuitive.

That's because the TX EQ does not behave quite the way it's described in the
manual.  The way the book shows it, the output at the high frequency end
(when using "-" TX EQ values) is "anchored" and you get low frequency
rolloff.  So you might think that if you were running at 2000 Hz in the
window, a "-" TX EQ value would reduce the power output.  But that isn't
what happens -- assuming 2.056 behaves something on the order of 2.032.

It depends on exactly where within that 3 Khz bandwidth you are actually
transmitting what the effect on power output level will be.  At the extreme
(TX EQ = -20), there is a 10 dBu RISE in ABSOLUTE levels.  The curve shape
looks like the manual, but the absolute levels increase above the "flat" 0
dB reference.  Roughly, there's a linear rise of 10 dBu from 500 to about
2000 Hz, and then the levels are constant through the top end of the
response.

So you crank in negative TX EQ to cut the lows, and you do that on a
relative basis, but you're also getting up to 10 dBu INCREASE in absolute
levels.

Seems to me you really want to run with TX EQ flat anyway.

Grant/NQ5T