Automatic Retransmitting Makeshift Repeater

Automatic Retransmitting Makeshift Repeater with MOSFET

Circuit : Miroslav Adzic

This circuit will be of interest to the radio amateur and anyone posessing two radios, (one of which must be able to transmit i.e. a transceiver). It is a self powered (audio derived) repeater circuit for receiving a signal and re-transmitting it via the other radio.

This little circuit can turn two hand-held radios into a makeshift repeater. Any radio will work fine as Radio 1, but Radio 2 must be a Yaesu, or some other type that also goes on the air when its microphone input is shunted with 1-2 kiloohms.

As soon as a radio signal opens Radio 1’s squelch circuit, a tiny amount of energy stolen from the audio signal turns on the MOSFET and it conducts as long as the audio is present. While it conducts, Radio 2 is on the air, retransmitting the content supplied by Radio 1 through C1 and P1.

The BS108 has a conveniently low G-S threshold voltage. The other components’ characteristics are not critical, but it would be wise to stay close to the values shown in the picture, or at least take them as a starting point for testing.

Source: http://www.zen22142.zen.co.uk/Circuits/rf/rxtx.htm

This entry was posted on Sunday, September 30th, 2007 at 5:05 pm and is filed under RF-Radio Frequency. You can follow any responses to this entry through the RSS 2.0 feed.