[TenTec] Orion Prog AGC Threshold

[Bill Tippett <btippett@alum.mit.edu>]

NT1Y wrote:
>I've been twiddling the Prog AGC Threshold control on
marginal signals and find that quite often there is a "magic" setting that
pops the signal out of the noise (actually, it sounds like the band noise
drops leaving the signal alone).

        Bill, you are definitely nearing the end of your Orion Learner's
Permit and ready for a real Driver's License!  Here are a few hints to
minimize your efforts to set AGC Threshold:

1.  With your favorite BW/Preamp settings etc, press Menu-RX-Threshold and 
tune to an empty area of the band.  Now turn Threshold up until you
hear the noise level drop and set Threshold to the level just before
the noise decreases.  This level will vary depending on band and noise
conditions.  On 10 meters it may be 2-3 uV and on 160 it will seldom be
below 20-30 uV and may reach as high as the maximum 192 uV on an
extremely noisy night (storm QRN).

2.  Exit Menu and highlight RFGAIN (normally 100%).  If you hear a very
weak signal right at the noise floor, adjust RFGAIN down gradually until
the signal comes out of the noise as you mentioned above.

3.  By leaving RFGAIN highlighted and also Menu-RX-Threshold
highlighted, you can easily switch back and forth if necessary.
However, if you set Threshold correctly in #1 above, you will seldom
need to go back into Menu and can readjust RFGAIN only as necessary
for very weak signals.  Leaving it at 100% you will hear nearly all
stations that are much above the noise floor without having to adjust 
anything.  In listening around in the Stew Perry 160 Contest this
weekend, I seldom adjusted RFGAIN or Threshold once I got everything
set up correctly.  Of course, as you noted, if the noise level increases
you may need to go back and readjust Threshold.

        As I've said before, learning to use Orion's AGC Threshold was the
most difficult transition for me in learning to use the radio.  Now that
you've reached this stage, you are hereby designated an Orion Driver!

                                                73,  Bill  W4ZV

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