[TenTec] RE: [Orion] Orion subreceiver

[Carl Moreschi]

The image signals should be at twice the third IF away or 24 to 28 kHz away
and only on one side of the signal and not both.   The current roofing
filter width is fine for this except it probably has an ultimate rejection
of about 60 to 80 db.  Very strong signals can still push thorough this.

Carl Moreschi N4PY
Franklinton, North Carolina
n4py at earthlink.net
----- Original Message -----
From: "Duane - N9DG" <n9dg at yahoo.com>
To: <tentec at contesting.com>
Sent: Wednesday, January 05, 2005 10:31 AM
Subject: Re: [TenTec] RE: [Orion] Orion subreceiver


> 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 at netscape.net> wrote:
>
> > "n4lq" <n4lq at 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
> >
>
>
>
>
> __________________________________
> Do you Yahoo!?
> Read only the mail you want - Yahoo! Mail SpamGuard.
> http://promotions.yahoo.com/new_mail
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec