N6KB wrote:
>If we were willing to give up some accuracy in the frequency readout of
the Omni VI (say for instance when not operating close to band edges) we
could just bend the BFO a little bit and get any audio note we like.
Perhaps with some firmware modification, and some interconnection with
the RIT control, we could make an upgrade that could give us control
over the audio beat note, without giving up frequency readout accuracy.
I'm not ready to take this challenge on right now. Maybe somebody else
will, and Inrad can sell the kit.
I'm in the process of getting the Omni VI of N4SU (SK) ready
to sell. In some of Dave's correspondence with Ten-Tec and N4TY
about setting up the #221 filter, I found this:
************************************************************
"Tyler--Thanks much for the 250 Hz filter info. I will
call Scott at TenTec today. I am disappointed that their
engineers would only go for a 500 Hz center freq. I
re-aligned the 6 MHz IF on my Omni V and used 400 Hz
center freq for years until it developed an intermittent
problem I couldn't fix. TenTec engineers said I was
upsetting the SSB operation but I operated SSB plenty
with no problem. The lower center freq also improved
WWV AM reception on 10 MHz.
Oh well -- 500 Hz is better than 600 and the filter can be
used down to 400 Hz I imagine. The present 600 filter is
way down and useless at 400 Hz."
**************************************************************
I haven't looked at the VI, but this might be possible.
You would have to be careful with the impact this would have
on other modes (i.e. SSB) as Ten-Tec noted.
It's interesting that the TS-930S did this in the
early 80's without fully programmable frequency control
(such as Orion has). You could continuously vary Pitch
from the front panel and filter alignment was perfectly
maintained. Variable bandwidth tuning (VBT) was also
perfectly centered on whatever Pitch was selected.
Kenwood may have patented this idea since I never saw
it in other analog rigs (although the Yaesu 1000 family
began doing something similar in 50 Hz steps). I think
the IC-781 may do something similar but am not familiar
with it enough to say.
I love the ability to vary Pitch (aka Spot tone) in
Orion. In the 160 contest this weekend, I set it to
400-450 Hz when running to catch most off-frequency guys,
but dialed it down below 300 Hz occasionally when needed
for very weak signals (i.e. VP2V/W3HQ 2W QRP who called me).
73, Bill W4ZV
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