Isle of Man Repeaters DMR Project

(updated 6 September 2015)

Following a lengthy incubation period, a project to provide Amateur Digital Mobile Radio (DMR) coverage to the Isle of Man has been launched and licenses have been issued.

On 20th June 2015, two proposals were submitted to the RSGB for complementary repeaters in the North and East of the island.

The licences for GB7BR (Bride) and GB7CA (Carnane), in the form of a variation to GD4HOZ's personal licence, were subsequently issued on 14th August 2015.

GB7CA will be co-sited with GB3IM-C, whilst GB7BR is co-sited with GB3IM-R. Both repeaters will operate at similar power levels to their FM neighbours and, because they will use a common antenna, they should have similar coverage.

The details of the proposals can be found on the ETCC website at the links given above.

GB7BR went live on 3rd September 2015 on a temporary antenna.

This project has been privately funded. GD4HOZ purchased the repeater for GB7BR, whilst GD6XHG has paid for GB7CA. Duplexers, cables and other hardware have also been acquired. Tony Hawker, G4CJZ has very kindly donated several ferrite dual circulators which form a critical part of the RF combining system at both sites. Other items have been bought, begged and scrounged from anyone whose hands could be prised open.

Please read the position statement from the two repeater owners regarding this project.

If you are at all interested in getting involved, please contact GD4HOZ, GD6XHG or the IOMARS committee. The costs associated with this project will probably hit £5,000 or more and so the best thing that any individual can do to help is to consider a donation to the IOMARS repeater support fund or a direct contribution to the repeater keeper. The second best thing that you can do is to use the system!

More news as it happens.

David Osborn

GD4HOZ

GB7BR Combining System

High power combining shelf donated to the repeater network
Two isolated combiners and one non-isolated
Closer view of one of the isolated combiners. The isolators prevent interation between the two transmitters
Wider View
This is a simple wilkinson combiner / splitter without isloators.
With each input rated at 75W, this is bound to get hot. At our power levels that's not an issue!
Closer view of one of the transmitter isolators
The lid of the combiner is home to the remaining components of the combiner system.
A Down-East Microwave PhEMT amplifier for the receive leg.
The duplexer (Black) and the common leg bandpass filter on the right. The blue cylinder on the left is a BPF in the transmitter leg.
The completed shelf ready for installation.

(note that the pictures are stored at their original resolution and may take a little time to download)