How does a radio duplexer work?

A duplexer, works very much like Telephone Hybrid Circuit. Telephone receives the voice from the same line it sends your voice to. But why can you hardly (if at all) hear your own voice on your speaker?

It filters the outgoing signal and the incoming signal using a different techniques.

One, as an example, is feeding your voice output, and the line input, to a differential amplifier.

The amplifier, removes your voice from what it receives from the Line (thus only the received signal

remains valid).

The duplexer, usually maintains a 30dB separation between sent and received signal. This can be done

because you know exactly what you are sending.

Lets say your output is OP, and your input is IP. Once the transmitter works, what you have in air is

IP + OP (What you receive and what you send together).

If on the receiver side, you subtract your own OP from what you get in the air (which is IP + OP), what remains will be the IP (or the received signal from the other transmitter).

For further technical details, search google. There is another aspect, which is the total amount

acceptable by the duplexer, which I cannot explain in few lines.

I hope this helped.

A ham duplexer is typically for either 2 meter (VHF) or 70 cm (UHF). The most common is 2 meter. The frequency offset is 600 kHz for this band. The duplexer is usually made from tuned cavities. These tuned cavities can be adjusted to some extent if you know what you're doing and have the equipment to tune them correctly. You can't adjust them to anywhere in the radio spectrum. You simply won't get a UHF signal through a 2 meter duplexer. Nor will you get a 2 meter signal through a UHF duplexer. IF you have an antenna that is designed to be used for both bands (yes, they exist and no, they don't perform all that well) you can use pass cavities and notch cavities to combine the two signals into one coax. Again, you have to know what you're doing and have the test equipment to tune everything.

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RE:

How does a radio duplexer work?

I'm trying to set up a repeater station and wondering how a duplexer comes in. I'm under the impression that it allows the repeater station to receive and transmit on the same frequency simultaneously... but is a duplexer an attachment to a standard repeater/transceiver, or is it a...

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