934MHz CB Radio – RingwayManchester

During the CB boom of the 1980’s there were many people on the air 24/7 on 27MHz but there was another variation of CB which many may have never heard of. 934MHz.

The use of 934MHz for CB goes back to the beginnings of the legal CB days in the United Kingdom. The original proposals were modified in terms of both frequency and antenna specification during its lifetime, but despite these changes, and an embargo on the import and manufacture of new equipment, the band remained with popular with enthusiasts and experimenters for many years.

Dismissed as a gimmick when it first appeared, so called `experts’ said that stations would be lucky to operate across the road with the specification allowed. It didn’t look promising with low power with low gain antennas and high feeder losses. The specifications were coupled with the view that operators were seen as lacking the technical background to work with these frequencies. The experiences and results from the early pioneers of 934MHz showed that the facts did not match these so called expert predictions.

A British company called REFTEC, soon produced the first practical 934MHz transceiver and matching antennas for the market. There were originally three models in total, starting with the MkI. Soon after, the MkII was released which was a really nice radio and was quite popular, and the REFTEC base station, which is extremely rare.

Other early rigs were the Grandstand transverter for 27 into 934MHz, and the ultra rare Westminster dual bander 27/934 base station. The last somewhat successful British set produced was the Uniace 400, but by this time imports were emerging from Japan.

It didn’t take the Japanese long to identify the UK as a potential market for 934MHz CB radio. Infact they were already exporting a similar system to Switzerland. The Commtel Personal NPR-934 was the first of the Japanese imports, followed by two similar handheld models and the Cybernet Delta One rig.

REFTEC are mostly responsible getting 934MHz CB started in the UK and a company called SELECTRONICS of Canvey Island set up the first specialist dealership. However it was Nevada Communications in Portsmouth who helped to accelerate the band’s growth with the Delta One rig.

The Cybernet Delta One was described as the `Mini Cooper’ of 934MHz. It was small, neat, full of features, had good ergonomics and was reliable and it took the band by storm. There were also two Clarion transceivers on the market.

These were state of the art personal radio system transceivers for Switzerland, with all kinds of selective calling and control features. The Clarion showed what might have been at the time.

Due to the cost of radios and the popularity of 27mhz, the use of the 934MHz band was patchy throughout the UK during the mid 1980’s with activity being confined to small geographical pockets. The intensity of operation increased southwards from Scotland, through the North of England and into Eastern and Southern England.

In Wales, activity was mainly restricted to the North and South coasts of the principality. In Northern Ireland and the Channel Islands, activity was limited to a few dedicated operators. The years 1986-88 were probably the golden years of 934MHz, with superb lift conditions reported.

Like any UHF frequency, day-to-day propagation at 934MHz is more or less line -of -sight. Even more so than bands such as 70cm. However, as the frequency is suitable for radar applications, it’s subject to reflected and scattered signals. This scattering effect can lead to some irregular signal enhancement and can also send signals round corners, producing unexpected signal paths between stations. This is similar to auroral propagation, but extremely localised.

Propagation both by ducting and refraction was also quite common on 934MHz. Local morning or evening temperature inversions would often enhance conditions. Also propagation over low-lying land or sea paths could enable ranges well in excess of 150km. Stations in low-lying locations, but with a good take -off for their signals, would often experience knife-edge bending of their signals.

Atmospheric conditions over far away ridges, could also bend the signals over the ridge and down the other side. Full blown tropospheric refraction propagation enabled sustained directional propagation over hundreds of kilometres on low power and with simple antennas.

One confirmed contact noted around 1988 from was Jersey, an island in the English Channel to County Antrim in ireland over 700km away.

Successful operation on 934MHz depended mainly on antenna location. As with most of VHF and UHF bands, the higher the antenna and the least amount of obstructions in the way, the better.

At higher frequencies obstacles cause more of a problem. Even mature trees in full leaf could attenuate signals at 934mhz so many users went mobile due to their home location not being suitable. This caused another issue because 934mhz was mostly unsuitable for car to car contacts, even over short distances. It was also limited for car to home base operations over distances more than 7-10km.

The best results came from marine mobile operations or from hilltops especially during lift conditions. Like 27mhz, the band was informal, but was better known for the high standard of operating between users. Operators stuck to a code of practice that was polite, friendly and sensible.

Users at the time said they hadn’t experienced some of the worst cases of abuse like those seen on 27MHz, and even some of the amateur bands around that time. The illegal use of linear amplifiers was generally frowned upon, although the limited availability of them prevented any serious abuse.

Power microphones were acceptable and some individual operators even tried out repeaters, phone patches, and various data communication modes, all of which were prohibited.

There was interest amongst some 934MHz operators in designating one channel nationally for use with packet radio for one to one communication, digipeating and the use of personal mail boxes but this never happened.

The band was populated with clusters of stations, separated by ‘no go’ areas, usually high ground or other barrier features. There may have been as many as 1000 estimated active stations still on air by the early 1990’s, with half as many again temporarily silent. Many 934MHz users held amateur radio licences and there were a few junior operators, but a high proportion of women on the band.

The calling channel was usually channel 10 or 20. Disappointingly, except under lift conditions, it was usually common to hear only one or two channels in use compared to the high level of use on 27mhz. A popular aspect of band usage was mobile operation from high ground, which had a large following in some areas.

Mobile antennas for 934MHz were mainly vertically polarised co-linears of various designs, including the original REFTEC models that look like cellphone antennas. Other antennas were over a metre long. The most easily identified, were the Nevada mobile collinears with their distinctive orange base, and air-spaced phasing coils. Collinears made good base station antennas as well, and many were shrouded for weather protection. Directional antennas mimicked amateur design antennas with commercial models made as derivatives of either loop or Yagis, quads, helical beams, skeleton slots and even dishes.

Many operators used a receive pre -amplifier, capable of boosting incoming signals by as much as 20db.

The 934MHz Club UK was the only specialist organisation representing 934MHz users. The Personal Radio Club of Great Britain existed for a time but wasn’t active by the early 1990’s. The 934MHz Club UK used to run contests on the band but in the late 80s the contests were discontinued by the club committee due to lack of support.

They did run some award schemes and also activity days and members congregated at some of the regional radio rallys.

Like 27MHz, call signs weren’t used on 934MHz CB however there were G9 test and development callsigns allocated to some of the experimenters. Test and development licenses were a useful concept which allowed people to carry out all kinds of research which may not be allowed on normal CB or licenced amateur bands. By the late 1980’s the cost of a test and development licence was around £50.

A number of 934MHz experimenters held test and development callsigns and they could often be heard on the air. The callsign was not used for normal communications so it wasn’t protocol to interrupt them as they were more than likely engaged in some sort of commercial work.

There were numerous test and development callsigns associated with 934MHz users such as, Clive G9BWZ in Gloucestershire, Fred G9BTN in Norfolk, Jim G9BSP in Southampton, the Citizens Band Association G9BRY and Andy G9BUP. There was also G9CBE and G9BWB, both to unknown operators.

There was a peak in operator numbers and a steady supply of good quality equipment but around this time, there was a serious blow to the whole thing. The government reallocated the 934MHz frequency to a commercial digital voice communication service, a proposed PMR like service for small firms and large commercial sites.

By the early 1990’s this service had still not materialised but the authorisation to manufacture or import 934MHz transceivers was withdrawn. The existing 934MHz users could continue to operate as long as their stations were capable, although new equipment became very scarce, and second-hand items were in short supply.

Despite continuing assurances that the band could continue to decline gracefully by natural attrition over many years, a significant number of operators opted to leave the band in.

During the late 1990’s the Radiocommunications Agency announced that the 934 MHz Citizens’ Band Radio service would be withdrawn on 31 December 1998. The Performance Specification to which all 934 MHz CB transceivers were manufacturer certified, was withdrawn in 1988 and since that date no new sets were manufactured or imported. The Agency allowed users of 934 MHz CB to continue to use their existing equipment but always made it clear that this was for a limited period.

The RA gave permission to Cellnet and Vodafone to operate analogue mobile telephones on a temporary basis in the 934-935 MHz band as part of a plan to reorganise this part of the spectrum and with the intention of increasing capacity for digital GSM telephones in the upper part of the 900 MHz band.

This was deemed necessary to accommodate the continuing enormous growth in the demand for mobile phones, in particular the new digital services, without adversely affecting existing analogue users.

Naturally, 934 MHz CB equipment would clash with this new usage and therefore they took the decision to withdraw the 934 MHz.

There is still some enthusiasm for 934MHz today both on the air and within online groups and equipment does come up on ebay regularly but this is still not legal to use.

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