Transmiting on duplexer in the same band

[motolover]

what will happen if i hook up a repeater to a duplexer that is in the same band but not tuned to the repeater frequency? will it damage anything? Thanks

 

[zz0468]

We don't have enough information to give you a definitive answer. It COULD...

One thing is almost certain... it won't perform like it should, i.e. excessive loss, excessive desense, excessive coupling of the transmitter into the receiver. Why would you even consider doing such a thing?

 

[pappy1]

what will happen if i hook up a repeater to a duplexer that is in the same band but not tuned to the repeater frequency?

Don't Know.

will it damage anything?

Probably, You will need two duplexers, one for transmit and one for receive, each tuned for the frequency that is to be used. As being in the same band our repeter receives on 145.31mhz and transmits .6mhz lower on 144.71mhz.

 

[N_Jay]

. .You will need two duplexers, one for transmit and one for receive, each tuned for the frequency that is to be used.

Hu?

Two filters, >>> One duplexer!

 

[pappy1]

The receive duplexer has to be tuned for the receive frequency and the transmitter the same, otherwise the signal would not be seperated. This is useing one antenna. Our repaeter has three canisters on each side. If one becomes detuned any at all it will not pass the wanted signal.

Yes, two filters, if filters being the duplexers is what you mean.

 

[zz0468]

The receive duplexer has to be tuned for the receive frequency and the transmitter the same, otherwise the signal would not be seperated. This is useing one antenna. Our repaeter has three canisters on each side. If one becomes detuned any at all it will not pass the wanted signal.

Yes, two filters, if filters being the duplexers is what you mean.

You've got your terminology wrong. The duplexer is the entire device - separate transmit filters, separate receive filters, and the interconnecting cable harness that ties all the pieces together. THAT is the duplexer. The "canisters" are called cavities. Each cavity is a filter. So, your duplexer has 3 cavities on the transmit side, and 3 cavities on the receive side.

 

[n1das]

THAT is the duplexer. The "canisters" are called cavities. Each cavity is a filter. So, your duplexer has 3 cavities on the transmit side, and 3 cavities on the receive side.

I've seen:
- notch only type having 6 cavities (3 on each side)
- combination pass/notch having 4 cavities (2 on each side)
- combination pass/notch having 6 cavities (3 on each side).

My favorites are the pass/notch types.

Every cell phone also has a duplexer in it, albeit a very small one!

 

[kb2vxa]

DON'T TOUCH ANYTHING! Get someone familiar with radio systems and in possession of proper test equipment to do it for you before you wreck something.

 

[N_Jay]

You've got your terminology wrong. The duplexer is the entire device - separate transmit filters, separate receive filters, and the interconnecting cable harness that ties all the pieces together. THAT is the duplexer. The "canisters" are called cavities. Each cavity is a filter. So, your duplexer has 3 cavities on the transmit side, and 3 cavities on the receive side.

What he said (but laced with a lot more sarcasm) :twisted::lol::twisted:

 

[N_Jay]

I've seen:
- notch only type having 6 cavities (3 on each side)
- combination pass/notch having 4 cavities (2 on each side)
- combination pass/notch having 6 cavities (3 on each side).

My favorites are the pass/notch types.

The cavity filters on each side do not need to be symmetrical.

You might have pass on on the RX and pass/notch on the TX.

I don't have a favorite, as the RIGHT one is best for the situation.

The filters do not need to be cavities. They can be Helical resonators, or even SAW filters.

Every cell phone also has a duplexer in it, albeit a very small one!

Nope. With the move to digital, most do not. They use TDD (Time Domain Duplex).

 

[N_Jay]

DON'T TOUCH ANYTHING! Get someone familiar with radio systems and in possession of proper test equipment to do it for you before you wreck something.

I have found too many techs leave the threaded rods sticking out where they can get bent or broken.

ALWAYS tighten them all the way down before leaving the radio site! :lol::twisted::lol:

 

[pappy1]

DON'T TOUCH ANYTHING! Get someone familiar with radio systems and in possession of proper test equipment to do it for you before you wreck something.

OK, Now we are getting somewhere.

 

[slicerwizard]

Every cell phone also has a duplexer in it, albeit a very small one!

As already noted, they are a dying breed and very much in the minority. Without simultaneous TX/RX, a duplexer is rather pointless.