The City of Birmingham Repeater
GB3CB RB14
Tx 433.350 mhz Rx 434.950 mhz
Ctcss 67 hz RMG Tone A

The GB3CB repeater came on air in 1976 over 30 years ago.
The Builder and Keeper then was Dennis Fitch G8IMN who's name can be see each week on the credits of BBC2s Top Gear.
The first repeater was made up from a Pye F460 Base with Cmos logic made by Chis G8FTU.
Aerials where two, four stack quad dipoles one on top of the other, Rx on the top which where so long they had to be pulled up the side of the 60 meter top block and then guied on roof. But the isolation was so good that only one Pye ae450 notch filter was needed in each line.

In the 1980s I be came the keeper where I changed the Base to a Storno CQF612 first a 7watt then a 20watt one, So getting to a full 25watt ERP from the site.
The front end had makeover by Graham G8HTH with gave the very good front end even better performance still to be beaten today.

The coverage was so good that we where asked by the RMG if we could put a notch in the coverage towards GB3NH Northampton which tried to share a channel with CB.
After the aerials had been blown down a couple of times I went to a single aerial working using a ProComm duplexer which had worked and still is working for the GB3EH repeater at Edge Hill. This was technically a better to go because the multipath nulls at UHF should fall the same, getting rid of the problem finding right spot for Tx and Rx in built-up areas.
Sad to say in time this duplexer didn't work as well as the one EH had.

In 1994 Hayden G8AMD became the keeper as I got the Salsa bug and hed to work away from Brum.

In 2007 John G8VIQ took on the challenge of care.
He has replaced the whole system from mains power plug to aerials.
I now works very well and you will find me on there now.

This is the new coverage map, See what you think?

Noel G8NDT

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