Located on the borders of Chigwell in Hainault, GB7CH is A new multimode digital repeater for South Essex & East London

Picking up the Aerial to be used by GB7CH from Dunstable Downs Rally

On air from 10th December 2020 the repeater, formerly installed at the Kelvedon Hatch Secret Nuclear Bunker, GB7KH, has been repurposed to provide digital communications using the top three most popular modes. DMR, Yaesu System Fusion and D-Star.

Repeater Specifications:

TX frequency: 439.6125 MHz
RX frequency: 430.6125 MHz
Colour Code: 3
TX Power (PERP): 7 dBW

Network: Brandmeister
Repeater ID: 234112
Slot 1: Dynamic
Slot 2: Static Talkgroups:
23511 (LEFARS)
235 (UK CALL)
2350 (UK Chat)
2351 (UK Chat)
2352 (UK Chat)
2353 (UK Chat)

Yaesu Fusion
Network: FCS
Default Group: FCS00291 – CQ-UK-WiresX

Default Reflector: REF001 C

Repeater aerial is the 4 stacked dipoles.

The repeater is a homebrew affair originally built by George Smart M1GEO and installed as GB7KH at the Kelvedon Hatch Secret Nuclear Bunker.

It consists of two Motorola GM340 Transceivers being fed by a Zumspot Modem on an Arduino, controlled by Pi-Star on a Raspberry Pi. A ProComm Duplexer provide filtering to enable the single dipole array to be used for full duplex transmit & receive.

It is planned to replace the Arduino / Zumspot with an MMDVM Hat for the Pi which should cut down the switching time of the repeater.

Repeater in Test configuration

Want to see what going on? well here is the: Dashboard Link

V1.1 Dec 2020