Although I think such a roofing would help some the Orion's
sub RX, and the Pegasus/Jupiter too. I think that you'll find
that these "ghost" signals are at +/-12 or 14 kHz away
(depending on radio model) as you move away from the strong
signal that is causing them. What is happening is that they
are images that fall inside the the first IF roofing filters
bandwidth.
Adding a narrower filter in the first (45 Mhz) IF should
alleviate this problem. That 1st IF roofing filter needs to
be narrower than the 3rd IF's (12 or 14 kHz) offset from its
injection frequency for it to help though. So wide modes like
FM will have to go or be bypassed when such a roofing filter
is in use.
I thought about trying such a mod for the Pegasus in the past
but haven't actually tried it.
Duane
N9DG
--- Barry N1EU <n1eu@netscape.net> wrote:
> "n4lq" <n4lq@iglou.com> wrote:
>
> >This may be another opportunity for INRAD. I think their
> roofing filter
> >for the MP is 75mhz.
>
> Yes, and the 4Khz wide filter showed no improvement in the
> MP's close-in cw performance. The Omni VI and Orion fitted
> with the 600hz (9Mhz) roofing filter performs so far above
> the nearest competition in tight 160M condx that it makes
> me want to avoid vhf i.f.'s. (Omni VI performance based on
> assumption and initial glowing reports from W2VJN).
>
> 73,
> Barry N1EU
>
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