> With regard to losing gain with the 250 Hz narrow filter and having to
> set the passband tuning to 750 Hz, it just ain't so. You set the offset
> to be whatever you want it to be. Mine is set for 450 Hz. There is a
> gain compensation jumper near the filter so you don't have to lose
> anything when using it. It's documented in the manual.
Yes, the manual tells you where to place the jumper to equalize
the gain. But, no, it doesn't equalize the gain, especially for
the pair of 250 Hz filters. I have experienced this on several
OMNI VI's, so maybe yours works well and I have experienced a
different run. Ten Tec understands that there is some loss with
the pair of 250's as I have discussed it with them.
Similarly, setting the PBT out of the 750 Hz range is a problem.
Have you ever tried it? You can move the offset to whatever
you want ref the 6.3 MHz IF, but the 9 MHz filter does not know
that, and your bandwidth there is 250 Hz centered at a 750 Hz
offset as far as I can figure. You can move a hundred Hertz
or so without a lot of loss, but not any further.
This has been my experience on at least two OMNI VI's. Your
mileage may vary. Let me know if there are any tricks to get
around this. I would love to hear them.
Clark
WA3JPG
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