Radio Shack HTX-400 owner manual Understanding Repeaters

UNDERSTANDING REPEATERS

Operation through a repeater, where you transmit on one fre- quency and receive on another, is called duplex operation. Oper- ation direct to another station, where you transmit and receive on the same frequency, is called simplex operation.

A repeater is a station that receives a signal on one frequency (the input frequency) and then retransmits that signal on a differ- ent frequency (the output frequency). Repeater antennas are typ- ically located at the tops of tall buildings or on antenna towers, so a relatively low-power signal can reach the repeater. The repeat- er retransmits the signal at a higher power. This gives your trans- ceiver the ability to communicate over a much greater range.

To use a repeater, you must know the repeater’s input and output frequencies. Repeaters are usually identified by their output fre- quency. Thus, a repeater that has an output frequency of 442.200 is referred to as “the 442.2 repeater.” To determine the input fre- quency, you must know the frequency offset (typically 5 MHz for the 70 cm-meter band) and the offset direction (+ if you add 5 MHz to the output, or – if you subtract 5 MHz from the output).

Whether the offset is positive or negative depends on:

•which part of the band the repeater operates on

•local convention

•proximity of repeaters using the same two frequencies

To determine the offset and the direction, obtain a copy of The ARRL Repeater Handbook (available from your local Ra- dioShack store or directly from the ARRL) which lists the loca- tions of repeaters as well as their frequency and offset information.

A + above the displayed frequency indicates a positive offset, while a – above the frequency indicates a negative offset. If nei- ther + nor – appears, the HTX-400 is set for simplex operation.

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