The UK Six Metre Repeater Network [1998]
Iain Philipps, G0RDI - August 1998
Iain's previous article on repeaters

Early last year I wrote that we were expectantly awaiting the formal permission from the UK licensing authority which would allow the establishment of FM voice repeaters here in the UK. The date, 1st May 1997, will forever mark (for me, at least) the end of an almost five year struggle to see the introductions of this facility here in the UK. The reasons that it took so long are many and various, and are not particularly relevant to readers of ‘Six News’.

Actually, when I wrote the original article (published in issue 53) I had already been in quite close liaison with most of the other UK groups who were working on building such devices. Also, my contacts with the RA (the UK’s licensing authority) were such that I was sufficiently confident to know that the end would indeed come on May 1st.

It had become apparent that with sufficient encouragement it would be possible to arrange for three of the proposed twelve repeaters to be brought into service in a co-ordinated fashion. After discussions with Bill (GØVDE, keeper of GB3EF) and Jon (G4TSN, keeper of GB3RR) it was agreed that those two repeaters, along with GB3AM would be activated at 1600 GMT on the appointed day.

I do not know what happened with the other two, but the first ‘real’ QSO took place on GB3AM between Martin (G4HKS/P), Jim (GØJIM/M) and Robin (GØVJI/M) within a very few seconds. Robin was quite close to the repeater site, while Jim was about 20 km to the east of the repeater. Martin cheated, since he was using a microphone plugged into the repeater itself!

The first three weeks of operation saw a sharp increase in activity on six metre FM generally, but simplex operation specifically. No, I do not know the answer to that one, either! Then a terrible thing happened. All of the ‘core’ members of the GB3AM repeater group set off to far off JO01KJ to participate in a 144 MHz contest. We were only gone three days. When we returned, guess what? The repeater was not working!

A cursory inspection and some casual inquiries revealed that there had been some magnificent electrical storms over the weekend (but not in JO01KJ – hah!). Our information was that there was more than a fair chance that the site/tower had suffered a lightning strike. I guess that would explain the physical absence of the BF988 front-end device.

GB3AM was back on line after an approximate 36 hours outage. The immediately noticeable difference was that all of the users appeared to have vanished without trace. Gradually the numbers grew, until we got back to our core of 20 (or so) regular users. As an interesting aside, one particular young lady at the RA hardly laughed at all when I told her the story. She did mutter something about just deserts, though…

Then there was the time when the same young lady received some mysterious e-mail asking "How much did you get for it?" What had triggered that question was the occasion where I had casually dropped into the site to investigate the non-operation of the repeater, only to find that it had been stolen! So whoever it was who though they’d acquired a very tidy looking Tait 72-85 MHz base station is going to be bitterly disappointed, no?

Of course, there are many other amusing anecdotes to relate, but they will have to wait for another time since I really want to get on and tell you about the other operational UK six metre repeaters. Here is the status of the network, as I currently understand it, in no particular order:

GB3RR (IO93JA, 50.820 MHz, 71.9 Hz)

I do not hear much from Jon these days, not nearly as much as I used to when we were comparing notes regarding various technical and political ‘opportunities’, anyhow. When I spoke to him a few weeks back he said that this Nottingham repeater was ‘performing to expectations’. Unfortunately, Jon had already indicated that he did not have very high expectations, since the Hucknall site is not particularly suited to coverage of a wide area.

However, Jon stresses that ‘RR nevertheless provides valuable additional mobile coverage for the surrounding area, and continues to provide a focal point for local six metre operators when they’re not further down the band chasing the exotic DX stations.

GB3EF (JO02PB, 50.720 MHz, 110.9 Hz)

After many e-mail and telephone dialogues, I was finally able to meet Bill for the first time only two days ago. I do not know how it happened, but I had been persuaded to lend a hand to… a radio club… with their VHF Field Day efforts. The chosen venue was a few miles north east of the Martlesham Heath repeater site, and even fewer miles north east of GØVDE’s house.

I had been aware that a number of folk had made quite scathing criticisms of the configuration and operation of GB3EF. I was pleased to note that my route between home and Dunwich would take me within very close range of that repeater. This, therefore, would provide Bill with an excellent ‘known’ mobile station objectively evaluate EF’s performance under mobile conditions.

Happily, I can report that I had no difficulty whatsoever in accessing that repeater using only 3 watts (I had reduced power) from locations where other stations claimed that access was impossible when using 25 watts or more. My conclusion, which, given a year’s experience with GB3AM, was actually a forgone one is that on the whole, folk need to take more care when installing a radio in their car!

Because of man-made interference (try listening to anything anywhere on 6M from outside a modern self-service filling station for a first class demonstration of this particular phenomenon) and the relative inefficiency of ‘amateur grade’ mobile antennas for the band, proper installation is critical if successful mobile working is to be achieved. Hint: just parking a ‘multi-band vertical’ on a boot lip mount is NOT going to work well! If you cannot use the roof, at least use the gutter! (pardon?)

GB3PD (IO90KT, 50.850 MHz, 71.9 Hz)

This is the newest of the currently operational six metre repeaters, and is performing well within expectations as I write. Unfortunately the selected site, atop a block of flats in Portsmouth city centre, is a less than ideal site for a repeater in this band. However, the site rental is very low, and the coverage is at least as good as the group had hoped to provide.

After a few minor difficulties with the receiver, and a change from the triple band ‘white stick’ antenna (the six metre repeater is co-sited, sharing the antenna system with the two metre GB3PC repeater) to a dual band ‘J-pole’ designed and built by John, G0WEH, things are going very well.

Being tucked away on the coast, activity is not particularly high and I am waiting to see what use is made of this repeater during the summer holiday season; I suspect there will be a marked increase in activity.

This repeater is a "clone" of GB3AM, in that it also uses a converted Tait 300-series base station and the PIC controller logic.

GB3AM (IO91QP, 50.840 MHz, 77.0 Hz)

I have probably already said more than enough about ‘Auntie Mary’, as it seems to have become known). It is just worth commenting that fixed stations with 10 watts or so throughout the Greater London area manage to enjoy some kind of service from this unit.

The ‘average’ mobile station (50 watts and a ¼ wavelength vertical whip) seems to be able to make use of the repeater from 95% of the M25 motorway, but fixed stations from far greater distances are often heard, with the bulk of the traffic confined to what is lovingly described as ‘drive time’.

GB3UM (IO92IQ, 50.740 MHz, 77.0 Hz)

This is a repeater that I was very pleased to know was active. The callsign suffix was selected as a memorial to the late Jack Hum, G5UM, who was a particularly keen six metre operator and an inspiration to many new licensees on all VHF bands (myself included, from 1979 onwards).

I know very little of the workings of this particular unit, mainly because the keeper (Adam, GØORY) seems not to respond to the e-mail messages I send him! However, my spies tell me that it is working well, and serves a significant proportion of the East Midlands area and has a reasonable amount of activity.

Actually, the week GB3UM came into service I found myself over on the Suffolk coast at Lowestoft. To my surprise, I found that ‘Uncle Mike’ was actually a good signal over there on the coast, although while I was within range I was unable to make a QSO due to low activity.

GB3FX (IO91OF, 50.810 MHz, 82.5 Hz)

This unit is co-sited with the GB3FN UHF and GB3FM microwave repeaters at Farnham in Surrey. Some folk had been expecting greater things from GB3FX than have been delivered, but I can tell you that the keeper (Dave, G4EPX) is entirely satisfied with the current performance. The major issue is that unlike the other repeaters on the site, a conscious decision was taken to mount the six metre antenna just one wavelength above the ground.

However, GB3FX provides substantial mobile coverage for large parts of Surrey, northern Hampshire, Berkshire and Oxfordshire therefore providing a particularly valuable contribution to the available six metre repeater coverage in southern England.

Worthy of note is that rather than invest a large sum in a custom-built antenna duplexer, the Farnham VHF Group elected to build their own using offcuts of Heliax™ as the resonant elements. While not nearly as efficient as the ‘real’ thing, with some hard work and concerted scrounging, such a duplexer can be constructed for perhaps as little as twenty pounds! This same design is also in use at GB3PD, where the space-saving attributes of the design were almost as important as the price.

GB3HX (IO93BP, 50.800 MHz, 82.5 Hz)

Again, I have scant information regarding this unit. I have spoken to the keeper (John, GØPRF) many times over the past few years, and the topic has usually been some technical nuance of six metre repeaters or other.

Last time I spoke to John, ‘HX was performing well from it’s high site close to Huddersfield and had proven popular with passing motorists.

In common with ‘AM and ‘EF, ‘HX uses a commercial duplexer as its antenna combiner, and is therefore a high performance unit. Since Huddersfield is not somewhere I travel to (generally) by car I cannot comment on the coverage, but judging by the site, significant sections of the local motorways ought to be well provided for.

GB3PX (IO92XA, 50.780 MHz, 77.0 Hz)

This unit is sited on a massive commercial tower at Barkway, on the Hertfordshire / Cambridgeshire border. Coverage is (for me) a little disappointing, since not only is the antenna at a comparatively low altitude, it is also screened to the South by the tower itself.

Again, this seems to have been a conscious decision by the group, and I hear rumours that they are planning to relocate the antenna system somewhat higher above the ground. I suspect that this would substantially improve the coverage to the North without making any real impact towards the South.

In common with most of the other UK six metre repeaters, ‘PX employs a converted 66-88 MHz commercial base station as the transceiver. The duplexer has also been converted from that band by Rupert, G4XRV and seems to offer very good performance, with low insertion losses and good TX/RX isolation.

GB3HF (JO00HV, 50.760 MHz, 103.5 Hz)

This repeater was licensed earlier this year but it is currently not operational. The group are busy working to prepare the Hastings site and installation of the antenna system is imminent.

The repeater itself will turn out to be a replica of GB3PD, in that I have prepared (yet another) Tait base station and logic combination. Jon, G4MDC is working on improvements to the Heliax™ duplexer design and it is hoped that this will provide significantly better performance than the one in use at GB3PD.

GB3AE (IO71PR, 50.720 MHz, 94.8 Hz)

Recently licensed after an enforced move to a new site near Tenby, this repeater is expected to become operational in the late summer or early autumn.

UK Six Metre Repeaters 

Callsign Loc        TX freq         CTCSS
GB3AE IO71PR 50.720 MHz 94.8 Hz
GB3EF JO02PB 50.720 MHz 110.9 Hz
GB3UM IO92IQ 50.740 MHz 77.0 Hz
GB3HF JO00HV 50.760 MHz 103.5 Hz
GB3PX IO92XA 50.780 MHz 77.0 Hz
GB3HX IO93BP 50.800 MHz 82.5 Hz
GB3FX IO91OF 50.810 MHz 82.5 Hz
GB3RR IO93JA 50.820 MHz 71.9 Hz
GB3AM IO91QP 50.840 MHz 77.0 Hz
GB3PD IO90KT 50.850 MHz 71.9 Hz

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