Paul Christensen wrote:
> Clarification:
>
> I realized that Bill's message was not transceiver-specific. My preceding
> message applies only to the Omni Six/Six Plus, not previous OMNIs whose
> filters may be compatible in the 9 MHz I.F. stage, including the OMNI V.
>
> The reason for my concern with the OMNI Six series is that a 2.4 kHz filter
> centered at 9,001.500 kHz is designed with a lower filter knee of 9,000.300
> kHz, leaving only 100 Hz of error for adequate passband of the CW BFO
> frequency. As long as the 10-pole filter is precise with predicable QC,
> this filter should still work with the Omni Six/Six Plus.
>
> -Paul, W9AC
Paul,
Thank you for your concern. My experience with the INRAD filter is the center
freq will be less than plus or minus 25hz. These filters are WIDTH spec'd at
-0hz +100hz; typically they will fall in the +50hz range. Passband ripple is
typically less than 1db. Another thing, they just work better than the stock
filter. I think they "match-up" with the existing circuitry better than the
stock filters. I would be surprised if TT is paying over $25US for the stock
filter.
Don't forget that the accuracy of the "BFO" is a major part of this equation.
After many tedious hours of parts substitution and tweaking I have finally got
my room temperature
( 70 deg +/-10deg/f) BFO stability down to plus or minus 5hz. I do leave my
OMNI VI (ug3) on all the time. I asked TT if they would make the ARRL Omni VI
BFO oven mod generally available; their response was that this was only a one
time deal. Oh well...
73 Bill Cook N4WC
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