Bill, thanks. I remember Sinisa's paper, but I never had much luck with
it. Nevertheless, I'll reinstall 1.373b5 and try exactly what you
suggest. There is no doubt that there was too much RF gain. However, I
did manipulate the attenuation, RF gain, and threshold and I would never
use the preamp on 40M anyhow. However, I didn't manipulate them in an
orderly fashion such as you have described. I'll let you know how I
make out.
Thanks for your help.
73, Joe
73, Joe
Bill Tippett wrote:
> K2XX:
> >I replaced 2.059d with 1.373b5 last night and the change in performance
> was both dramatic and negative. There was an enormous increase in RF
> gain, which was further increased when invoking NR. I tried
> manipulating the Threshold, Decay, Attenuator and NR setting without
> much improvement. To make 40M CW even marginally listenable, I had to
> use 12 dB of attenuation. The NR seemed to act properly with the
> attennuation. The Threshold setting seemed to have no effect and there
> seemed to be a non-linearity in the RF gain control.
>
> Almost certainly an indication RF GAIN is set too high.
> Also, AGC Threshold and RF GAIN are now linked in all V1
> versions following 1.371. To set RF GAIN correctly:
>
> 1. Set AGC Threshold = 1 uV for all bands, all AGC options. Set AF
> GAIN to mid-scale.
> 2. Tune to an area of the band with antenna connected but no
> signals.
> 3. Adjust the following, in order, until you cannot hear band
> noise when switching between no antenna and your antenna (e.g.
> ANT 1 vs ANT 2 with nothing connected to ANT 2):
>
> a. Preamp Off
> b. Attenuator (6/12/18 dB)
> c. RF GAIN
>
> 4. When you can no longer hear band noise, then increase RF
> GAIN until it just becomes comfortably audible (but not beyond
> that point).
>
> Anytime I hear people complain about Orion being
> "noisy", it is usually a sure indication there is too much
> gain in their setup. The above is adapted from a paper
> Sinisa YT1NT wrote below, but it was prior to 1.372 when
> Threshold and RF GAIN were integrated into one control.
>
> http://www.geocities.com/va3ttn/UsingOrionRX.pdf
>
> 73, Bill W4ZV
>
>
>
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>
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