After looking at a 564 schematic it does appear that Y2 (standard 2.4kHz)
could be replaced with a 9 MHz 1.8kHz or 500Hz filter for the roofing filter
and N1 and N2 (Y3 and Y4) can be 9MHz CW filters as well. If I understand
the cascade scheme, Y2 can have Y3 or Y4 cascaded with any of four filters
in the passband (6MHz) IF.
The gain jumpers JG1 and JG2 are set in the LOW (jumper) for TT 218 or 220
(SSB) filters while the 216, 217 and 219 (CW) filters require high gain.
In my OMNI-VI+ , I originally had 500Hz in N1 and 250Hz in N2 using the
standard 2.4kHz filter at Y2 along with the passband filters of 2.4kHz,
1.8kHz, 500Hz, and 250Hz but found after several years that I seldom used
the 250Hz filter in N2 and at the same time wanted to have some wider choice
on CW and a narrower option for SSB. I bought a 1.8kHz SSB filter for N1,
moved the 500Hz filter to N-2 and sold the 250 Hz (9MHz) filter. At that
point I just used the N2/500 or 250 passband combinations for digging out
the weak CW DX (S-1 to S-2) 2kHZ from their huge pile-ups. I may have lost
some CW selectivity but the overall flexibility of the radio for SSB and
Digital DXing was greatly improved.... your opinion may be different as well
as your needs.
73 es DX,
Gary - AB9M
Sent: Monday, January 24, 2011 10:17 AM
Subject: Re: [TenTec] Omni VI 1st IF Narrow CW Filter Enable?
Do you have the instruction sheet? It can be wired to work off of
either N1, N2, or full-time. If it was not using one of the narrow
switches you would certainly notice it on SSB. I'm still trying to
figure out if installing the 9MHz CW filter into the N1 position would
cause the roofing filter to drop out, but I would doubt it.
That would be quite the CW setup to have the CW roofing filter, and
INRAD CW filters both IFs! I believe you can install the CW filter in
either position, so if the roofing filter is controlled by N1, N2 would
bring the 9MHz CW filter into the circuit, too. I don't think you can
easily use N1 to control both. I'm sure it *could* be done, but getting
things working normally would be the first task.
I'm not sure about the gain setting but you probably would want the
high gain with 20 poles of filtering :)
On Sun, 23 Jan 2011 18:31:12 -0800
"Don Jones" <email@example.com> wrote:
>My OMNI VI with OPT 3, it is not a VI+. I have been monkeying around
>with the DIP switch on the INRAD roofing filter cca and the jumper
>next to the "narrow filter".
>It seems as though the OEM narrow filter is bypassed. I am wondering
>if the INRAD Mod is bypassing the "now installed" 1st IF cw filter.
>The INRAD Roofing Filter is a "CW Filter". I did notice one
>switch/jumper configuration that the received signal strength on the S
>meter drops 3-4 s units. I have not checked that config in a ugly
>pile-up to see if that is the config that selects the roofing filter
>and the 400Hz INRAD 1st IF CW filter.
>From: NL7VL [mailto:firstname.lastname@example.org]
>Sent: Sunday, January 23, 2011 7:01 AM
>Subject: Re: [TenTec] Omni VI 1st IF Narrow CW Filter Enable?
>Did you get the install instructions for the INRAD roofing kit? There
>are a couple different ways you can install it, one of which is to use
>N1 or N2 soft switches to activate it. The other way, as it's installed
>on mine (VI+), is to have the roofing filter installed full-time. I
>have the 2.4K roofing filter.
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