After my 500 and 250Hz filters changed today from the way they were
acting previously, I decided to do a master reset to see if that would
help -- it did! I also did a user reset at the same time, so I don't
know for sure what cured things -- resetting the menus to the factory
defaults or resetting the user things to the defaults, or both.
Anyway, now the filters tune like they did before. Additionally, all of
the AGC selections now act more like you would expect then to. Don't
know how that bug got in there, but the reset definitely improved things.
Even NR has some (a little) effectiveness with a 100Hz BW.
I enabled both filters and set their CF offsets to where they seemed to
be right previously. I did not change the factory default sidetone/spot
pitch of 670 Hz and noticed that there was no apparent attenuation in
either filter. The Ten-Tec filters have more insertion loss than the
wide ones and Ten-Tec explained to me that they follow the narrow filters
with an amplifier to make up for that loss.
Then I discovered something not mentioned by Ten-Tec, nor have I heard it
on this reflector:
If you change the sidetone/spot pitch more than about 100Hz from its
default of 670Hz, you begin to notice some attenuation from the narrow
filters -- moreso on the 250 than the 500Hz filter. Aha! Here's why:
Although you can center the filter offset in the filter menu for for a
pitch of 670Hz and at the same time you can switch between UCW and LCW
with no change, when you choose to set up the offsets while using a
different sidetone/spot pitch (and try to make UCW and LCW equal), a
different offset is necessary to keep the xtal filter centered on the DSP
filter. When the sidetone/pitch is set different than the 670Hz default,
the CF offset will be different. If you set the sidetone/spot pitch to,
say, 550Hz and you adjust the CF offset for maximum signal (you can use
the S-meter for this if you have a steady signal source), when you switch
to the other sideband (i.e., go from UCW to LCW), the signal will be much
weaker on the other sideband. Previously I was trying to tune the offset
for equal signal strength in UCW and LCW (and ending up with the correct
offset for a pitch of 670Hz), therefore the xtal filters were not
centered in either DSP filter passband and the S-meter reading would
decrease when I went from the 500Hz filter to the 1000Hz filter (and much
more noticeable when going from the 500 to the 250Hz filter.
I would like to set up everything on CW for a sidetone/spot pitch setting
of 310Hz (the lowest the Orion allows), even if it meant I could only use
UCW or LCW (but not both), but the limit of +/-250Hz CF adjustment in the
menu is not enough to be able to accomplish this.
So here's the problem:
Something has to be done so that the CF offset adjustment remains the
same when the user changes the sidetone/spot pitch from 670Hz, and he can
still switch between UCW and LCW and not notice any change in the signal
level/pitch. I'm not sure that this can easily be achieved with the
Orion because it would necessitate something akin to moving the the
center of the DSP filter passband up or down as needed to follow the
change the user makes from the default pitch of 670Hz.
Meanwhile I'll set the pitch as low as I can (possibly 500Hz?) and tune
the CFs for max signal on either UCW or LCW and forget about using the
other CW sideband.
BTW, the hardware blanker now works with narrow xtal filter bandwidths,
so the master reset fixed that problem also.
If your Orion seems to take a nosedive and, for some unexpained reason,
something doesn't seem to work as well as it did before, try doing a
reset by holding the MAIN RX/TX button in while powering up.
To be continued.....
73, de Earl, K6SE
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