Robert11 wrote:
Hi Dave,

The reason for the A/B switch is that I have only one Scantenna in the
attic, but I splurged over the years, and recently, and now find myself with
a Uniden and a GRE scanner.

Have one upstairs, and one downstairs.
So, want to switch my single Scantenna, depending on which I'm listening to.

Can always use a rubber duckie, I guess, on the GRE as it's a handheld, but
the Scantenna is much better, and I find that I'm using the GRE pretty much
as a base unit a lot.

Best regards,
Bob

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"David G. Nagel" wrote in message
...
Robert11 wrote:
Hello,

Would appreciate your opinions on the following, please:

I have two scanners that I now have connected to a single Scantenna
antenna in the attic.
Receiving only.

The coax comes from the antenna to an A/B push-button switch I bought
from Grove.
It's a cheap switch, only $20, and made in China. They imply on their
web site that the body
is die cast metal, but it came to me with a plastic body.
http://www.grove-ent.com/SWC01.html

It's their SWC01, supposedly good to 2 GHz, and uses F connectors.

It appears identical to the TVC brand AB-90 switch from Home Network
Supply, which says on their description that
there is 90 db isolation.
https://www.homenetworksupply.com/pr..._id=5854125807

Pushbutton A is arranged so that it switches the antenna to the upstairs
scanner, while pushbutton B switches it to the coax leading to the
downstairs scanner.

Well, big surprise.

I can push button B, but yet hear (at much reduced volume) conversations
on the upstairs scanner.

Sure doesn't seem like 90 db isolation.

Is this what is to be expected on these cheap switches, or possibly just
a bum one, or... ?

Any thoughts would be most appreciated.

Thanks,
Bob




Bob;

90db of isolation is not the same as absolute isolation. There is still
some RF bleed from one line to the other line that a sensitive rf amp can
detect and send on to the detector.
Is there a reason for the a/b switch or just your feeling that you need to
switch the antenna from one radio to another.

Dave WD9BDZ


Bob;

Why don't you make a second antenna. They are easy to make and will
perform as well as the commercial antenna you already have.
When I first got into Amateur radio my transmitting antenna was a 19"
piece of coat hanger. This was bent near one end and soldered to a
antenna connector. This very unglamorious thing was stuck into the back
end of my transmitter and performed very well. You can make something
slightly more attractive for your upstairs receiver for just a few cents.

Dave WD9BDZ