Unfortunately there is no simple way to do this except to reduce the
isolation by reducung the number of cavities involved. The basic concept is
to make band-pass band-reject duplexer assembly that has a 50 ohm load in
the direction of the antenna with a High Impedence in the direction of the
duplexer or away from the antenna.
It depends on exact multiples of 1/4 wave pieces of coax. Reducing the
number of cavities reduces the loss but broadens the bandpass skirt of the
filter allowing for interference on the commercial frequency.
If you already have the cavities all you need is the multicoupler harness
which you could construct.
The harness should be:
antenna port - 1/2 wave coax - feedthrough port
| |
| | 1/4 wave coax (Critical length)
Pass Cavity Reject Cavity
|
|
Radio Equipment
I believe there are more articles on the Repeater Builder website concerning
the theory of this.
Good luck
Eric Meth - ve3ei
> Thanks Eric, that would be the first-class method. As I alluded to in
> my original post, Skipp025 posted a method of combining two repeaters
> that didn't seem too complicated. Is there a relatively inexpensive
> way to do this in my case, maybe using one or more pass cavities that
> I have already?
>
> Laryn K8TVZ
>
> Date: Fri, 12 Aug 2005 02:33:48 -0000
> From: "Laryn Lohman" <[EMAIL PROTECTED]>
> Subject: Re: Adding a Radio to a Repeater Antenna
>
> --- In [email protected], "Eric Meth" <[EMAIL PROTECTED]>
> wrote:
> > Laryn.
> > The best way to do it is to install a multicoupler, tuned to your
> > simplex frequency 446.925 between the duplexer and the antenna. The
> > multicoupler has a frequency seperation of at least 1 MHz so it will
> > not interfere with the 452/458 MHz frequencies. Insertion loss on 446
> > will be approximately 3 db. The following is a line drawing attempt:
> >
> > Duplexer ----- multicoupler ----- Antenna
> > | | |
> > 452tx 458rx 446.925 tr
> >
>
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