K2XX wrote:
>First, let me comment on diversity reception. <SNIP>
Joe, one of the most useful applications for me
was in the CQ 160 CW Contest. I used Beverages as
the input to Main/RX ANT and put my TX antenna on Sub
RX, of course with both Main and Sub assigned to VFO A.
This allowed me to hear stations that my primary Beverage
direction might have missed (i.e. calling from a null in the
Beverage pattern).
>Barry and Bill, I hadn't tried narrower bandwidths with the Orion because
>I expected the SSB to be unintelligible. I remember Bill's original post
>to the MP reflector with his carrier offset recommendations. They made a
>major difference in received signal intelligibility. I have even carried
>it one step further when I hear sigs with muddy audio, usually DX; I
>adjust the offset to whatever setting yields maximum intelligibility. I
>have often commented that the control should be on the front
>panel. Similarly, the effect on SSB transmitted audio is also quite
>dramatic and easily seen on a scope. I just went and checked, and I was
>using -100 Hz offset on RX USB this weekend. I had played with the PBT on
>the Orion a little before settling at +250, but maybe I should have done a
>little more experimenting.
To check for best intelligibility, tune Orion to a
"known" SSB frequency. Pick one of the 75m nets
where some fanatics will tell you if you are 1 Hz off-
frequency. ;-) Now set DSP = 1600 for a "worst case"
and adjust PBT for best intelligibility. The fact you
thought +250 Hz sounded best could be due to you
being slightly off-frequency when adjusting PBT. I've
found most people in S&P mode tend to tune in USB
signal carriers about 100 Hz low and LSB signals
about 100 Hz high. I'm not sure why this is but it's
true for me. I often offset my TX by +100 Hz when
in S&P mode to compensate so my TX is not 100 Hz
too low when calling stations.
If this were the case for you, PBT +250
would actually be accomplishing 2 things:
1. Compensating for the fact you were 100 Hz
off-frequency to begin with.
2. Additionally adjusting for the 150 Hz intelligibility
factor for narrow voice bandwidths.
The best way to check is as I described above.
>Frankly, I thought I was using an 85 dB decay on the Orion AGC. As I was
>writing my original post, I went and checked to be sure and was surprised
>to see it at 8 dB. I have been fooling with PSK31 a lot lately and
>probably changed it while in that mode. (BTW, I'm using the N4PY software
>to set the AGC and that's why I can get an 8 dB decay setting.)
If you were truly using 8 dB/s, this would be
terrible for contesting since the receiver would not
be able to recover from strong splatter, and would
likely mask weak signals. It would be equivalent
to Slow AGC in the MP which is also not a good
idea for the same reasons. As I said, try 80 dB/s
(i.e. Fast) and 0.00 Hang (0.04 at absolute most).
>I have very little need for the NB at this QTH. Bill, I went back and
>read your original post. Frankly, I'm a little surprised that the NB
>works on white noise, and I´ll check that out. However, every time I have
>compared the two rigs on weak signal reception, mostly CW, I find little,
>if any, difference. It may be that my requirements are less demanding
>than yours. I am only a casual contester. On the other hand, I really
>go out of my way to pull weak sigs out of the mud even with routine
>QSOs. I will continue making comparisons.
I generally have no need for the NB here
except for an occasional electric fence on 160m.
However I did discover how well it dropped my
already low noise floor on 10m. You should be
able to check this by simply tuning to 10m when
it is dead (not difficult to do these days!) and
alternately engaging and disengaging the Hardware
NB. I hear a very noticeable drop in white noise
when I do this.
>I should also comment, that I have found that invoking the NR often
>increases the noise. Another correspondent suggested turning down the RF
>gain when that happens. He commented that the apparent noise level seems
>to increase, but there is in fact an improvement in S/N ratio. Generally,
>I run the RF gain just above the threshold where noise is audible. This
>weekend 15M was very quiet and I was at about 88 setting.
There is a known problem with NR
interacting with RF Gain. I know this is on
Ten-Tec's list to address but it will probably
be on the back burner until their work on
the rumored new release is done. Your 15m
RF Gain setting sounds about right to me.
73, Bill W4ZV
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