[TenTec] OMNI VI 9MHZ filters
Clark Savage Turner
csturner at kcbx.net
Wed Oct 24 08:26:11 EDT 2007
On Oct 23, 2007, at 10:09 PM, Paul DeWitte K9OT wrote:
> I put in a 219 250 hz filter in the 9 mhz if slot. It replaced a 400 hz
> Inrad filter. I find that it has quite a bit of attenuation (maybe
> But it does reduce the QRN a lot. This is on 80 & 160m.
10 db would be too much for a normal filter, in my opinion. The OMNI
VI has a little jumper to change the gain for that filter, it helps.
Check on that.
The other thing to check is that you haven't got the PBT and other CW
filter adjusted so that your center frequency is not quite where it
belongs for the 219. You have to have everything set for the 700 Hz or
so tone. If you've got the 285, say, and your PBT is adjusted for a
higher (or lower) tone than 700 Hz, the 219 will sound way down.
> Do others find this or maybe I have a bad filter. And yes I have the
> in the high gain position. And boy does it narrow up the passband.
I'd do some quick checking of the solder connections and the basic
seating of the filter to start with, unless the jumper for the gain of
the filter fixes things right away.
> I think that I tried a 221 filter and did not like it for some reason,
> dont remember. Different center frequency?
Yes, the 221 has a lower center frequency, you have to be happy with a
500 Hz (was that it?) tone.
Clark Savage Turner, J.D., Ph.D.
Professor of Computer Science
Cal Poly State University
San Luis Obispo, CA. 93407
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