Simple Low-cost Demo Repeater

This project is based on 3 of my earlier projects - 'Coupling a commercial VHF handheld to an external antenna' , 'Fox Hunt Attenuator' & 'UHF on a VHF Rig'.

Parts required are a couple of Rubber Ducky Antennas, suitable connectors, a single OA5 diode and a metal enclosure.

Demo Repeater

Also needed are a MF local oscillator, a VHF local oscillator, 2 VHF handhelds & a UHF handheld.

The schematics are as shown below.

For in-band operation the 600 kHz fundamental crystal oscillator output is mixed with the incoming signal.

In-band Demo Repeater - Schematic

For cross-band operation the 290 MHz 5th harmonic of the 58 MHz overtone oscillator is used.

Cross-band Demo Repeater - Schematic

In-band & cross-band repeater operation is easily demonstrated using the handheld rigs.

Down-link signals are quite strong inside the shack.

However the range of the demo repeater is yet to be checked.
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