Martlesham Radio Society - G4MRS


G4MRS Main Page

UHF/Microwave Beacons - DX Cluster - 6M Repeater

BT has for many years graciously provided free facilities for the beacons, DX Cluster and repeater as one of its 'community return' projects.

On the 10th floor of the Martlesham Radio tower, are the microwave beacons, DX cluster and voice  repeater. G4MRS operates beacons on 23, 13, 10 and 3cms for UK and Europe, a DX Cluster as well as a voice repeater on 6 metres. The main racks are shown below left.

UHF/Microwave Beacons (GB3MHL - GB3MHX - GB3MHS - GB3MHC)

The pictures below centre, show the rack for the GB3MHL, GB3MHX, GB3MHS and GB3MHC beacons.

The GB3MHL has two units at the top (with fans). The black box below that is the GB3MHL driver. Below that is the driver for the GB3MHX 3cm beacon. The GB3MHX multiplier and both beacon antennas are out on the galleries (on the outside of the radio tower).

  • GB3MHL - Operating on 1296.830 Mhz is the top unit

  • GB3MHX - Operating on 10368.830 Mhz is near the top

  • GB3MHC - Operating on 5760.830 Mhz is in the middle

  • GB3MHS - Operating on 3400.830 Mhz is the bottom beacon unit

  • The PSU is at the bottom of the rack

The far right picture shows one set of the slotted aerials for GB3MHL attached to the first and second floor aerial galleries on the Martlesham radio tower. There are two sets of aerials, one on each side of the tower (one pointing East and one pointing West). To give an idea of scale, the gallery fences are made from 2 inch scaffold pole and is about four feet high. Click on the centre picture to get a larger view of the aerial pointing SW (towards the UK).

All Racks

All Beacon Rack

Lower Part of Beacon Rack

The slotted aerials for one of the MRS beacons (18 Kb)

GB3MHL 23cm slotted aerial (side one of two pointing SW)

DX Cluster (GB7DXM)

The club also operates a DX Cluster - GB7DXM. This Cluster has several links to various other clusters. In the past, linking took place east to ON4DXK across the North Sea. The ON-link was one of the International gateways for the UK Cluster network. That role is now fulfilled by GB7DXK. GB7CDX also provides a secondary route along with a connection to GB7DJK - providing de-duped Internet connected traffic. All the cluster components are shown above right.

GB7DXM Cluster rack


GB7DXM Access


GB7DXM Access


Six Metre Voice Repeater (GB3EF)

Details on the 6M repeater GB3EF are available in several places on the Internet.

The picture right shows the half-height rack-mount unit, two radios, node controller and laptop and behind are the cavity filters.



Note: This site is run by the voluntary membership of the BT Martlesham Radio Society, affiliated to the Martlesham Research Sports and Social Committee. It is a non-commercial organisation and is not  representative of BT plc or any of its other ventures or companies.   Last updated 21/7/07 - 1996-07 Darren Hatcher