Please click HERE to go to our NEW web site.

These pages are no longer being updated.

Please also note that the "Contact Us" e-mail address, shown here is no longer available.


SITE LAST UPDATED ON: Thursday, 12/03/2015 @ 01:37 UTC.

DVU37 - Output 439.4625 MHz - Input 430.4625 MHz.

GB7JB is funded solely by donations from its' users and supporters. There is no club or group to join and no annual membership fee. We rely totally on your good will.

The system is located in South Wiltshire, in IO81vc, co-sited with GB3JB, and provides coverage across South Wiltshire, South Somerset and North Dorset.

GB7JB is a 70 cm Digital voice repeater, based on DMR TDMA Mototrbo technology.
It provides TWO simultaneous channels. One is for local chatting, whilst the other is connected to the Regional Cluster / Network.

Tuesday, 25 November 2014

GB7JB UPDATE - 26th November 2014

Hi All,

For those of you who are still wondering if GB7JB is something that you would like to support, please take a look at the following animated .gif image.

This shows the predicted combined coverage, for mobile stations, of the 5 repeaters forming the DMR TDMA "Regional Cluster / Network", which you would of course be indirectly supporting, by helping to get GB7JB, on the air.

The 5 Repeaters are:  GB7AA, GB7BS, GB7DR, GB7SD, and of course GB7JB.  (You can click on the callsigns to visit the relevant ETCC pages).

It also shows the impact on the overall coverage, when GB7JBs' individual coverage, is removed.

You will note that GB7JB has a significant impact on the overall coverage.

From a technical standpoint, the DMR TDMA system offers a significant advantage.

This being that each repeater is actually TWO repeaters in ONE.

Thus users of GB7JB, will have two simultaneous channels, or slots, available to them.

One will be connected to the "Regional Cluster / Network", thus enabling users of GB7JB to work stations, who fall within the overall combined coverage area, no matter which repeater the other station or stations, are actually using.

The other channel, or slot, will enable you to have a "local natter" to stations within the individual coverage of GB7JB.  As shown below.

So, two repeaters for the price of one .....

And of course, NO background noise .....

As you will have noted, so far I have received donation pledges from 28 individuals, the value of which totals up to £1,125.

For GB7JB to go ahead, I need to secure pledges to the value of £1,600 as a minimum, by the 31st December.

If this value is reached, then I shall require the pledges to be honoured, during January 2015.

The £1,600 is to cover the cost of purchasing the Motorola Mototrbo Repeater, a secure 3G/4G internet router, and hopefully two additional 250AH batteries, to bolster the support capability at the site.  Although I note that the matching batteries, to those already on site, have recently gone up by almost £50 each !

I have personally already sourced and funded the antenna, feeder, duplexer, 24v to 13.8v regulator, and other sundries, etc.,

I do hope that you can see the benefits of supporting a 70cm DMR TDMA repeater in this area.

If you have any questions, please feel free to contact me, via e-mail.

Please send your donation pledge to:

** Remember to include your Full Name, Callsign and the amount pledged.

Cheers & 73's
Dave, G3ZXX

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