934 MHz UK CB Band
20 channels at 934 MHz were made legal to the British public at the start of legal UK CB in 1981, alongside the 40 channels on 27MHz. At first the frequencies ran from 934.025 to 934.975 (50kHz steps), but this would change later, in 1983. Things were very quiet at first, as it took some time for manufacturers to get such complicated UHF technology working and available to the public.
In the July ’83 issue of Citizens Band magazine it was announced that the channels would be moved down 12.5kHz (from 934.0125 to 934.9625) in line with a CEPT plan. (At this time the first legal cordless home phones were legalised on 47/1.7 MHz too, mentioned here to show how unused to mobile comms we were back then!)
Citizens Band magazine reported very little 934 activity, and Mack the Hack had only just managed to get to try out the band. Only about 500 rigs had been sold, from Reftec only, and spread thinly around the nation. Callsigns were often made from the owner’s Reftec radio serial number, such as “Unit 271”. Grandstand was about to go into production with a rig+transverter combination. Apparently business users were using ch 1 to ch 10 by informal agreement, with CB as we know it on the top channels 11 – 20. (That seems logical to me, yet some people complained at the time, believing that business should stay off CB. However, CB was far cheaper than “proper” business radio back then, and the licence conditions DID allow business use so long as it wasn’t abused to sell anything over the air)
Citizens Band magazine – 934 channels actually moved in accordance with CEPT plan. Reftec radios would be available soon with the new frequencies, and the first models could be sent back for retuning.
934-1 Reftecs (.025) could still be sold until 30/4/84, and used until the end of 87.
934-2 Reftecs (.0125) sold from late 83 onwards.
Citizens Band magazine – Reftec 934 review (p26)
The Japanese introduce their Personal Radio Service on 903-904, with I.D. numbers (and traceable transmissions!), selective calling and automatic channel assignment, etc.
The Swiss follow the Japanese PRS system, with what seems destined to become a US/Euro standard, only with 40ch at 934-935.
Citizens Band magazine – Grandstand LA83 934 Transverter / Bluebird combo review (p26)
The Grandstand system was supplied with a normal 27MHz rig the ‘Bluebird’ (but worked with any 27FM rig) which had to be set to Channel 1 (it was filtered such that no other channel would work). The 934 channel was selected on the transverter itself, using 20 crystals – one per channel! The unsynthesized approach is so much more primitive than would be possible now in 2010! It appears to have been slightly more sensitive than the Reftecs, but quite a cumbersome option, and a little too selective using a 10kHz receiver at 27MHz. Technical review results followed in the May issue (p30). A later model the LA84 never went into production.
Reftecs were supplied with 40ch selectable, to allow owners to hear the new Swiss system (on 934.x375 and 934.x875 channels), but still would only TX on the UK legal 20.
The Reftec BS-934 Homebase (photo in CB Citizens Band May issue) was available.
The 934 MHz Club UK formed to keep things running smoothly and champion the rights of owners.
Citizens Band magazine showed (p26) an early prototype of Telecomms’ new 934 radio – later to become the Delta 1.
Citizens Band magazine – Telecomms in Portsmouth (renamed as Nevada in 1987) get their new Cybernet Delta 1 934 MHz rig ready for launch (review on p26), to join the Reftec and the Grandstand transverter system LA83.
At this time it was reported that the calling channel was 10 in the south and west, with some use of 14 elsewhere, but the use of 20 was gaining some momentum.
End of ’84
Reftec ceased trading by the end of 1984, having supplied an estimated 800 radios, and Grandstand gave up too (just 150 sold), leaving the way for radios like the Cybernet Delta 1 and Kestrel Commtel to corner the market in the spring of 1985. Kestrel’s Commtel ( NPR-934) was a well engineered Japanese 903-905MHz rig, converted to the UK spec.
Telecomms had 1000 Delta 1 rigs on the way at the start of 1985, with another batch of 1000 to follow.
Some 934 users started to notice interference from the new analogue TACS cellular phones, which were close by in a neighbouring band (935-950 at first, later extended down to 917) – continuous control channels were operating 24/7 at 935.56-936.06 & 943.06-943.56.
Thus led to IF-related ‘images’ breaking through into the receivers. The mobile phones were vertically polarised, so there were some early experiments to avoid the interference by working ‘flatside’ (horizontal) – which usually meant directional beams to complicate matters a little – it was difficult to make omnidirectional high gain aerials with horizontal polarisation, which meant phased arrays of some sort. Flatside did seem to travel farther, though, which was a plus for hilltop DXing.
Citizens Band magazine – Kestrel Commtel NPR-934 review (p12)
The Uniace 400 934 rig was available, and a month later a single channel handheld from Gem Communications of Sevenoaks (Aug issue p10). Due to difficulties sourcing the high tech components required for such a high frequency band, a couple of other prospects had sunk without trace in the meantime, like ones from EMS (British manufacturer of Electro-Medical Supplies who made the respected Mercury 1040 27MHz rig), Magpie (who made the advanced Autoscan 5000 27/81 rig) and further rigs from Grandstand. A keenly awaited rig from Everite (4 Coventry Road, Hinckley, Leics), the “Warlock” dualband 27/934 version of an Audioline 341 had been promised during 1984 but also came to nothing. A small photo of the Warlock prototype was in CB Citizens Band April 84, and the May issue showed a Uniace Minster Dual Band base station, also mentioning a possible Uniace Britannia 201 dualband mobile and the economy Uniace Cavalier 101 single band 934 rig.
Citizens Band magazine – Uniace 400 934/81 rig review (p14)
Citizens Band magazine – p15 – reports that the wallies are now on 934 in force, to the surprise of Mack the Hack who hadn’t noticed any problems in his neck of the woods.
The DTI announced plans for a new, European standard, Personal Radio Service to run alongside 934/81 in the UK for a time, sharing the same band.
Citizens Band magazine – prototype Mitsubushi handheld shown in Mack Chat, advertised in May as the MT370.
An alternative club was formed – the PRCGB (934) Personal Radio Club GB – with a focus on heading toward the PRS type of service as used elsewhere.
The remaining UK CB magazine reported a growing popularity of horizontal polarisation to counter the cellular phones interference.
G4ONF advertises cavity filters to solve cellular phones interference.
Citizens Band magazine – first ad for a new handheld, the NPR 900. News that Commtel also ceased 934 in 1985. The Uniace 400 being discontinued was a rumour – but was confirmed in the Dec 86 issue.
End of ’86
There were an estimated 3,000 users of 934 around the UK.
An order prohibited the sale of rigs other than to MPT 1320 & MPT 1333 standards. As the Performance Specification MPT 1321 to which 934 MHz CB transceivers were manufactured was withdrawn, no new 934 sets were manufactured from that date and none were imported. (August or December? Is this another case of Announcement versus Date of Effect, which makes historical research from the web so difficult?!)
No import or manufacture of 934 equipment, in preparation for the new SRR system in 1990 (which never happened in the end). This was later named DSRR (Digital Short Range Radio), to occupy 933-935 MHz alongside a paired band 45MHz lower at 888-890 – allowing base/mobile use on paired channels, or single frequency simplex. Control channels were to be 888.6625 and 889.3125 (933.6625 & 934.3125). European legislation included technical specs like the ETSI standard I-ETS 300 168 (max 4W), Decision ERC/DEC/(93)01e of 12th March 1993, and “T/R 20-10 E” 1990-93.
DSRR was a lame duck though. Manufacturers failed to show any interest, as prepaid Pay-As-You-Go mobile phones had caused an explosion of new users of GSM by then (the “2G” digital mobile phone system that replaced the analogue TACS, with the attraction of SMS Text Messaging, GSM still being in use in 2010), and it was such a cheap option that a two-way radio system simply couldn’t compete. The whole idea was shelved, officially withdrawn on 1.November.1996
It was too late for a reprieve for 934/81 CB though, which was discontinued by the UK Government. From the 1988 bombshell, owners were allowed another decade to use 934 until the final day of 31.Dec.1998, and then the band was later reallocated to the extended E-GSM band 925-935 (paired with 880-890). UHF CB also ran out in Switzerland 5 years later, with their 933 Band closing 31.Dec.2003.
934 MHz UK CB now illegal to use.
You will often hear that we lost 934 to mobile phones, but it was really the DSRR idea which signed 934’s death warrant. We could have had those oft-promised extra 20 channels by reducing the spacing to 25kHz, but that never happened in the end.
Cybernet Delta 1 – click for full size pic.
934 came into its own for hilltop DX, and base use, rooftop-to-rooftop, with huge ranges available during tropo “lifts”. Ask an Amateur with experience of 430 and 1290 MHz, and they’ll tell you just how good a band halfway between would be!
Even now in 2010, people still talk about how great 934 was for them. Rigs still change hands on auction websites, and I believe there are still some enthusiasts experimenting on the air, fitting in between the mobile phones where they can.