BBC Tower BBC Tower
What do you mean by "that's a bit ambitious?". No, of course it isn't the new quarter wave for the GB3OK repeater, but what better place to start on the subject of radio history in the south east? The BBC's television transmitter mast at Crystal Palace has always laid claim to being among the most adventurous and successful of post war engineering feats. At 710 feet high and standing on the site of the sadly fated Crystal Palace, the mast can been seen for many miles in every direction.

The mast once hosted the Amateur Radio Repeater of GB3LO, which later became GB3SL. With the transmitting aerial located on the second leg up, as high from the ground as Nelson on his Column, it had a great coverage. Sadly, I feel, we lost a big chunk of the south east's radio history when GB3SL ceased transmitting and closed down completely a couple of years ago.

This left me thinking what a big hole had been left in the 2mtr repeater coverage in Kent and the south east. I had heard a few rumors where various people had talked about coming up with a replacement, but nothing ever seemed to mature from those rumors.

It must have been around September 2003 when the nucleus of the idea first sparked into my mind and I set about a feasibility study, which led to a few months of of intense research. This in turn led us to where we are now. The first step was to find the equipment. I was fortunate enough to locate and purchase two Philips FX-5000 base station repeaters, four cavity filters, two battery backup supplies and the power supply unit. The two FX-5000 repeaters are 24 volt, 19 inch rack mounted units, with 100% duty cycle and were originally configured to operate around 148MHz. All of this equipment is of the highest commercial quality and in mint condition.

However, as this equipment became another piece of furniture in our hallway, I had already tested the water at a number of locations in my search for a site, including my own home. I managed to secure us the site we have now, which is itself steeped in amateur radio history. Located at Well Hill, Chelsfield in Kent, it's the site that once hosted GB3NK on 433.100MHz until it's re-location to Wrotham in 1976, and more recently, GB3NWK which operated two microwave beacons on 1296.81MHz and 2320.85MHz. At 600 feet ASL this has to be considered a prime site.

However, before any of this had even taken place the search for a callsign had been underway so that the application for a licence could get started. GB3OK, standing for Orpington, Kent, was the brainchild of my wife Jeanette, G1UPT. It's turned out to be a fortunate suggestion and one that has already attracted a catchphrase since Arthur, G0MLV was heard to say "is everything GB-OK" over the radio. Since then I've had many people ask me if everything is "GB-OK" with the new repeater.

Talking of licenses, and if I may be allowed a little poetic licence of my own (Please forgive me Sir Winston Churchill):

"This isn't the end. It's not even the beginning of the end. But it's the end of the beginning".

Welcome to the Genesis of the Bromley Repeater Group and GB3OK.

Tony, G1HIG..... (Founder Member)

In Remembrance.

Since writing the above, it is with great sadness that we have to announce on Thursday 18th August 2005, Arthur G0MLV of Greenwich passed away.

His humour and wit will be missed by all.  Arthur Rest In Peace.

Taken from another article.

The original 2m repeater to serve London was GB3LO (R7) situated at Crystal Palace in South London. 'LO' was first operational in 1974 from the QTH of G8AAI on Epsom Downs,Surrey, moving to Crystal Palace in 1975. The equipment in use on 'LO' at the time was a Pye 'Westminster' base station with a rather complicated logic system, including 'time out' tone window and various modes of operation.

In 1977 a standby repeater was constructed using a Yaesu FT2F for receive and 'Westminster' modules for the transmitter with a very simple logic system. This simple logic system was a success so the complicated version used in the original repeater was converted and reinstalled. Unfortunately, the repeater suffered from 'considerable abuse' and it was decided to set up four individual repeaters to cover essentially North, East, South and West London in an attempt to de-focus the attention that one repeater attracted. These being respectively, GB3NL (R7), GB3EL (R0), GB3SL(which was GB3LO renamed) (R2) and GB3WL (R1).

It was agreed that all four repeaters would become operational on the same day, with similar, simple logic systems. The existing, standby GB3LO repeater was pressed into service at Enfield as GB3NL and took over the old 'LO' channel (R7).

Over the years there have been a few modifications to the repeater. In November 1981 a 'Storno' was installed. One significant event was a lightning strike in July 1987. This vaporised the antennas and damaged the cavities and mains cable. Remarkably, only one transistor succumbed to the strike. The present repeater is still the Storno and the antenna is a 'J Beam' C5 fed through a 'hexalator'. This is essentially a device to enable transmit and receive to take place on a single antenna. This, together with cavity resonators prevents interaction between Tx and Rx. The height of the antenna is some 57m above ground level.


First there was GB3OK on 2mtrs, then the 70cms repeater, GB3LK, was added.

Later, GB3OK was replaced with a D-STAR unit and became GB7OK.  A short while later GB3LK underwent a callsign change and became the new GB3OK. 

Confused?  You shouldn't be.  It simply means both repeaters now have the 'OK' suffix and the current setup now looks like this:

GB3OK:  70cms FM - 430.900 x 438.500 (7.6 MHz split) 82.5 CTCSS (with Echolink on Node: 280040)

GB7OK:  2mtr D-STAR - 145.7125 x 145.1125 (600 kHz split)

All is "GB-OK' at Orpington now.

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