Technical Specs

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

Picking up the aerial for the repeater at the Dunstable Downs Rally back in 2017. I had plans even back then!

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.

Location: JO01ao

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
TG 23511 (LEFARS)
TG 235 (UK Call)
TG 2350 (UK Chat)
TG 2351 (UK Chat)
TG 2352 (UK Chat)

If using Dynamic Talk Groups on slot 1, when you finish your QSO, can you please key up TG 4000 to disconnect from the Talk Group. It will stop unnecessary activity on the repeater, the static talk group generate enough traffic as it is!

Please do not configure your radio for Dynamic Talk Group operation on Slot 2.

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

Default Reflector: REF001 C

The Repeater Aerial is the 4 stack array on the top of the mast. It has great take-off to the South and West and limited take off North and reaches out to about the M25 to the east.

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 Bandpass filter enables 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 and reduce the number of possible points of failure.

Repeater in test configuration. (Procom filter out of view)

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

V1.2 Oct 2021