The NEW DMR GB3JB became operational on Saturday 30th April 2022.

Prior to this date, GB3JB had been operating as an Analogue FM repeater, since November 2007.

The new hardware is a Motorola DR3000 TDMA DMR repeater, and is connected to the South West Cluster of 13 DMR repeaters, linked together via Slot 2, TG 950. Click HERE for more information on the SWC.

DMR TDMA technology is the internationally and communications industry agreed and approved OPEN standard for VHF and UHF communications between 30 Mhz and 1 Ghz. .Thus, it is not proprietary and/or tied to a single source manufacturer, with all that these factors imply.

TDMA DMR is not compatible with D-star or Fusion systems, which are also not compatible with each other, either.

Thanks to TDMA DMR technology, GB3JB now provides what is effectively TWO simultaneous and independent repeater communication pathways from the ONE repeater on just ONE repeater channel.

GB3JB is Powered by the Wind, the Sun and the Generous Donations of our Supporters.

Note: Since GB3JB is only powered by the Sun and Wind Power, during December and January it is likely that the repeater will go off air due to there being little UV and limited wind power. These outages can last from a few hours to several days, and are defined by the control technology which is designed to prevent the batteries from being over discharged. Further information is available on the ‘Technical Stuff page.


2m &-& Channel RV63 &-& Input: 145.1875 MHz &-& Output: 145.7875 MHz &-& 25w (14 dBw) ERP

Motorola VHF DR3000 &-& TDMA DMR Tier II &-& Colour Code 5 &-& Slot 1 = TG9 + DOD TG’s &-& Slot 2 = TG950

Loc: IO81vc &-& 745 ft (227m) asl &-& Single 3 dBD Collinear &-& Timeout 180 seconds &-& Part Of The South West Cluster

The above image is provided by the ETCC, and a more detailed map can be found HERE.

Obviously, there are other 2m repeaters operational on RV63, and users should be aware that under some conditions GB3JB could suffer interference from users of these other repeaters.

It should also be obvious that users of GB3JB could well cause interference to users of these other repeaters.

It is good operating practice, to only use the power that you need to be able to access any repeater. Therefore, if you only need 5 watts to access GB3JB, don’t use 50.

If you represent an Amateur Radio Group, Club or Society, etc., and feel that your members would like an introductory presentation on DMR TDMA technology and it’s capabilities, or would like to discuss the development of your own DMR TDMA repeater addition to the SWC, please feel free to contact G3ZXX via his email.

DMR TDMA technology is open-source with lots of manufacturers and consequently more choices in hardware and significantly cheaper prices.

FDMA technology D-Star and Fusion, for example, are proprietary. No choice in manufacturers, they are incompatible with each other, and of course the industry approved technological standard is TDMA DMR.

Site Safety & Security.

Obviously, at a site with a relatively easy unauthorised public access, safety and security is a priority.

We therefore try to do our bit. A couple of examples are shown opposite.

We have signs warning not to climb the tower.  Even though we have installed anti-climbing panels, idiots will always be idiots.

We have also provided warnings as to the use of 24 hour CCTV facilities on the site, which cover both the internal areas of the locked and secure barn and the external areas outside of the barn.

If you are not directly associated with the servicing and maintenance of GB3JB and it’s associated equipment and facilities, or directly associated with the farming of the land itself, you enter this privately owned site, totally at your own risk.

There is no public right of way across the site, and no unauthorised public access at any time.

We use cookies to improve your experience and to help us understand how you use our site. Please refer to our cookie notice and privacy policy for more information regarding cookies and other third-party tracking that may be enabled.

Our email address is: &

© 2020 - 2023 GB3JB Repeater - Site last updated: 22/03/2023 @ 1420 UTC - SWC Page

Created with
Mailchimp Freddie Badge