fully functional Cross-Band Repeater with 2 Transceivers andFM / D-Star Conversion

A Crossband Repeater with FM - DV conversion allows to use a simple FM handheld transceiver for D-Star QSOs. It extends the operating range of the handheld TRX a lot, makes really fun and has an excellent speech quality. 

The D-Star side of the Crossband Repeater is connected to the external antenna of the home station and is set to a frequency of a D-Star Repeater.

A second small indoor antenna, or even a dummy load, is used for communication to the handheld radio. Due to the DV/FM conversion in the Crossband Repeater we can use any cheap FM handheld for D-Star QSOs.

This Crossband Repeater is also very useful in regions where D-Star QSOs are distorted by hills or other reflecting objects. In this case FM signals have better quality. The Crossband Repeater then converts the FM signal into D-Star and sends it to a D-Star Repeater.

This picture shows the basic configuration:


The handheld transceiver talks to transceiver-2 in FM mode. The analog signal is sent via the repeater controller to the D-Star transceiver-1. TRX-1 digitalizes the signal and sends it to a distant D-Star Station. This of cource works also in the other direction.

This application does not require dual-band transceivers. Cheaper monobanders also do the job. The only requirement is that TRX1 and TRX2 must work in different bands.

A lot of solutions are possible to build the repeater controller. I have made an absolutely minimalistic circuit, small and easy to build, but offers the full functionality:


The analog LF inputs and LF outputs are connected via two pots for level adjustment. Squelch and PTT are connected via a switching transistor (any NPN useable). That's it, the Crossband Repeater is ready.

It depends on the used transceivers how they are connected. Here is a picture of the conenctions to my two mobile radios:



use the right band of the IC-2820 for D-Star. Then it is possible to use the (otherwise usually unused) speaker output-2.
set the right band of the IC-2820 for packet operation. Then the radio will also use the squelch line for the right band.

! The band for the handheld transceiver must be in another band then D-Star to avoid interference between FM and DV signals.

This very simple repeater controller has no security switch-off function. Therefore use it ONLY if you have full control over the equipment !


This circuit is a microcontroller driven crossband repeater controller which implements a couple of security and switching features:


Version Feb 2009 / DJ0ABR