See at the bottom ...
skipp025 wrote:
>
> > Identical IF's in the same chassis area can
> > be a problem ... unless everything is very
> > well shielded *and* all interconnected
> > wiring is fully filtered ... even then may not
> > be sufficient.
>
> Very true
>
> > This is the reason the radio equipment
> > manufacturers use a shifted IF on the
> > second receiver in such systems.
>
> Actually, only one reason of many
>
> > The Mitrek / MSR2000 systems use a 10.8 MHz
> > Shifted IF ... for more details, see
>
> There can be co-equipment, receiver image or
> local signals, which require an IF Shift or
> change to high side injection.
>
> Two stories come to mind, one was a large mix
> birdie. The other is a high powered non radio,
> industrial equipment oscillator on 10.7MHz
>
> Both had nothing to do with co-located same
> IF frequency radios.
>
> If you "flip" the injection chain to the high side,
> understand that any digital (dpl or data) word
> information will be "inverted" at the discriminator
> output.
Also, if the receiver has Automatic Frequency Control
- AFC- then the discriminator diodes must be reversed.
>
> cheers,
> skipp
>
> skipp025 at yahoo.com
> www.radiowrench.com
73,
Neil - WA6KLA
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