--- Kevin Berlen <[EMAIL PROTECTED]> wrote:
> Over the weekend, I added a second UHF control
> receiver at one of the sites
> I take care of. The control RX antenna is up about
> 150ft. Previous to
> adding the new RX, I could easily access the first
> RX about 25 miles out.
> Since adding the second RX, I can only access either
> one about 12-15 miles
> out. I simply put a "tee" connector on the
> polyphaser and connected both
> lines to it. Not the best engineering practice, but
> I have gotten away with
> it before. Does anyone have an idea about how to
> properly match two
> receivers to one antenna? The receivers are located
> in different racks in
> different parts of the building. I know Motorola and
> GE had passive devices
> to do this job. Is there a way to build something
> "homebrew" to do this
> job? TIA, and 73,
>
> Kevin, K9HX
>
You will usually get a 3 dB loss (or more) by using a
tee or a normal splitter. The Mot 2 RX combiner was
designed for 2 RX at somewhat removed frequencies. It
had 2 tuned circuits, which reduced the loss, so it
depends on how far apart your two RX's are.
If you have a good preamp, you can usually put the
splitter after that, and see very little loss, since
most pre-amps have more than sufficient gain. Another
cheap splitter is a tee with a QW section of 75 ohm
cable on both legs. From the end of each QW, attach
your 50 ohm cable to the individual RX's. This works
very well if your RX impedences are close to 50 ohms.
You can also measure the sensitivity at the input to
the splitter, and right at each RX input, to see what
your overall loss is. If it's much more than 4 dB or
so, you might check out all the components.
Joe
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