Bill, I just wanted to let you and the list know that I had a chance to
check out your procedure for RF gain, etc. adjustment this weekend on FW
1.373b5. There was a vast improvement in performance, although I didn't
spend as much time as I wanted to with it, and I'm still evaluating.
I wound up using 18 dB of attenuation and the RF gain at 60-80 with a
threshold of 1.02 uV on 30 and 40M CW. When I invoked the NR, the noise
(gain) did increase, but readjusting the RF gain got it back under
control. I haven't really checked the settings out on very weak sigs,
etc, but there's no doubt that a vast improvement was obtained.
I did have to do a master reset (after the initial reset after loading
the new FW) when I lost all output power. Others have reported similar
glitches with 1.37x FW. I had occasionally observed power output, mike
gain or audio output losses with 1.37x myself.
Another issue: If the NR works by narrowing the receive bandwidth in a
manner similar to manually reducing selectivity of the filters (I
presume that the NR uses different algorithms for CW and SSB.), why have
an NR at all except for its automatic feature? Interestingly, I had
reported that FW 2.059d seem to clip the signals when using NR at a "1"
setting. However, I also noted that the clipping could be minimized by
very carefully centering the sig in the passband, which seems to support
the argument that NR works by reducing BW. OTOH, with weak sigs no
amount of centering helps.
73 and thanks for your help.
Joe
K2XX
Joe Giacobello wrote:
> 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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