Thread: Tech....
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Old 01-17-2008, 06:38 PM
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Groucho Groucho is offline
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Default Duplex vs. Simplex

Originally Posted by Uncle Ben View Post
Soooooooo...since I was playing hookie during Groucho's first class I now seek on-line education.

Right now when I key up on lets say 145.145 (tone set at 107.2), the transmit frequency jumps to 144.545. Does this mean I'm running Duplex? If that is true then if I wanted to stay Simplex is it just a matter of disabling the freq shift?

*EDIT* I started this at 2:17 and got called away, then finished it before realizing all the other posts!

Silly billy! The class is in February, not January!

In order to utilize one antenna for the actual repeater site on the mountain, the radios there use what is called a duplexer. This is a device that, simply put, makes it so that the electronics don't fry in the repeater receiver when the transmit is transmitting.

Most of the repeaters in use that are not linked to other repeaters(we'll go over all this in the class) operate on what is called "full duplex". Full Duplex is a communications mode in which a radio can transmit and receive at the same time by using two different frequencies. This difference in frequency is called a "shift". Standard VHF shift is +/-600 KhZ, depending on where the frequency is in the band.

The opposite of this is what Chris was saying, Simplex. It uses no offset "shift ", so all transmitting and recieving has to be done separate of the other. Simplex is what is used on CB(AM).

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