Retrotechtacular: 934 MHz CB Radio

The radio spectrum is carefully regulated and divided up by Governments worldwide. Some of it is shared across jurisdictions under the terms of international treaties, while other allocations exist only in individual countries. Often these can contain some surprising oddities, and one of these is our subject today. Did you know that the UK’s first legal CB radio channels included a set in the UHF range, at 934 MHz? Don’t worry, neither did most Brits. Behind it lies a tale of bureaucracy, and of a bungled attempt to create an industry around a barely usable product.

Hey, 2019, Got Your Ears On?

Did this car make you want a CB radio? Stuurm [CC BY-SA 3.0]
Did this car make you want a CB radio? Stuurm [CC BY-SA 3.0]
Mention CB radio in 2019 it’s likely that the image conjured in the mind of the listener will be one from a previous decade. Burt Reynolds and Jerry Reed in Smokey and the Bandit perhaps, or C. W. McCall’s Convoy. It may not be very cool in the age of WhatsApp, but in the 1970s a CB rig was the last word in fashionable auto accessories and a serious object of desire into which otherwise sane adults yearned to speak the slang of the long-haul trucker.

If you weren’t American though, CB could be a risky business. Much of the rest of the world didn’t have a legal CB allocation, and correspondingly didn’t have access to legal CB rigs. The bombardment of CB references in exported American culture created a huge demand for CB though, and for British would-be CBers that was satisfied by illegally imported American equipment. A vibrant community erupted around UK illegal 27 MHz AM CB in the late 1970s, and Government anger was met with campaigning for a legal allocation. Brits eventually got a legal 27 MHz allocation in November 1981, but the years leading up to that produced a few surprises.

Governments tend to be their happiest when in the driver’s seat, and thus they were reluctant to simply licence the same CB allocation as the American one. During the protracted period of campaigning by CBers over the end of the decade it became obvious that there was a very significant demand for an allocation but they could not be seen to let the illegal CBers win. Their first tactic was to propose a 928 MHz UHF allocation with a 500mW power limit which was rejected by the CB lobbyists, so the final allocation became a 27 MHz one with a 4W limit on an odd set of frequencies incompatible with the American ones, and using FM rather than the American AM. Alongside this they clung to a UHF allocation, which was finally given at 934 MHz.

The result was that Brits had two CB allocations, one of which on 27 MHz that worked even if it wasn’t as good as the American sets, and one on 934 MHz that didn’t work very well at all and had eye wateringly expensive equipment. All the wannabe Rubber Ducks gravitated towards 27 MHz, but 934 MHz became an exclusive pursuit for enthusiasts; essentially another amateur band in which propagation and DX chasers plied their craft.

The Government hoped that having two CB allocations unique to the UK would create a home-grown industry supplying British-made CB rigs, a seductive idea for politicians with little knowledge of how the electronic hardware industry works. For example, the same idea has been touted in recent years as a reason behind drone licencing laws. But in reality, the market was soon flooded with UK-spec 27 MHz radios from Far Eastern manufacturers. By contrast 934 MHz rigs were rare, with only one or two models being brought to market. The object of desire was the Cybernet Delta One, a video review of which we’ve placed at the bottom of the page.

Christmas 1981, The Day The Dream Ended

If you were an AM CBer who bought a legal UK 27 MHz FM rig in November 1981, then life continued as usual as the community moved to the new band. They had a triumphant couple of months as victors savouring their spoils, but then Christmas came around, and everyone who’d sat in the cinema watching Convoy and fantasised about CB lingo got a rig of their own. Overnight the dream was shattered, followed swiftly by the UK CB bubble bursting as the novelty wore off. 27 MHz CB continues in the UK with a set of European channels now added to the UK ones, but never again will it be anything approaching cool.

Meanwhile the 934 MHz channels continued to provide an experimentation ground for enthusiasts, and every month in Practical Wireless there was a column devoted to its propagation. In 1988 as the mobile phone industry began to expand, there was a demand for UHF frequencies, and the Government stopped the sale of new 934 MHz equipment. A decade later the allocation was officially removed, and those 934 MHz rigs are now illegal to use, though they do still appear in radio rallies from time to time.

The UK CB boom had a surprising effect, in that it brought a whole new audience into radio as a hobby and caused a corresponding boom throughout the 1980s as many of those people went on to obtain their amateur licences. If you meet someone with a G1 callsign there’s a good chance that’s the generation they came from, so ask them if they had a 934 MHz radio. Even if they didn’t, they’ll probably be able to tell you more about this interesting side chapter in radio history.

Now, sit back and enjoy M0OGY’s review of a 934 MHz radio.

44 thoughts on “Retrotechtacular: 934 MHz CB Radio

      1. I purchased a returned ‘faulty’ Tandy HT, It wasn’#t faulty it was for the CEPT block of 40 channels and there was minimal use in my town so they assumed because it didn’t work because he couldn’t talk to anyone (there was a very active community on the regular 40 channels at the time), even friends with their CB’s on same channel. I only paid £7 for what Tandy was selling for £129 at the time.

        I used it for a while and was quite pleasing to work Europe using the stock antenna several times with it’s 1.5W.

      2. The classic late 70s ones were the Archer Space Patrol set, not sure if they came out earlier. Damn there were a lot of version I see from a quick google. Grabbed a pair myself a few years back, figuring I might be able to hail them across a campsite from a proper CB in the vehicle or camper. Haven’t really tested range though since.

        1. I recall in the late 70s/early 80s there being a battle over the 27MHz band with r/c modellers on one side and the illicit CBers on the on the other.
          I think it died down after CB was allocared legal bands but the r/c guys had no love for the CB cowboys!

          1. CEPT resolved this by reserving “alpha” channels, i think there are 4 or 5 of them, which are spaced in between regular CB radio channels (need to look at frequency table). this is where the “+10kHz” feature on rather illegal cb radios comes in handy.

      1. I’m sure you’re very proud of your hilltop to hilltop, yagi to yagi 2500 yard record. Urban conditions, mobile to mobile ain’t gonna be like that, neither are most hams only gonna use half a watt.

    1. 934 had 8 Watts not half a watt and reports of quite impressive ranges being achieved. You culd also use directional beam antena as well as normal vertical antena. Sadly I culdent afford a 934 rig but I did get a chance to use one.

    2. I was Hertfordshire area rep for 934 club, brilliant band, polite operators, no idiots or dee jays, and good range considering frequency, with no overseas interference to jam local contacts, making CB unuseable as happens on hf CB. 934 still clear last time I listened, never used by fone companies. Sadly 934 was a UK only spec so not many radios built, and the better expensive Japanese kit was derived from their own uhf CB allocation on 903 – 905mHz. With PMR446 being a pan European allocation, it seems logical to bolt on more channels and 5 watts to enable a modern uhf CB slot fit for purpise just as Oz, NZ and other Australasian nations have. This approach would be more robust than the UK only 934, with a much bigger market, radios would be so much cheaper.

    3. Then again 5 watts on 26-27 MHz was pretty much useless when the band was “open”, in quotes because of QRM combined with QRN, an open band meant useless for local communications. A company I used to work for tried to use low band CB as business radios, one day I couldn’t communicate with a coworker mobile to mobile I could see a 1/2 mile away. A situation where 450 or 900 portable radios should have worked quite well.

  1. Don’t forget, the original “CB” was up at 450MHz. The US allocated it around 1947. But it was too high in frequency for that early. So very simple tranwceivers, superegen receivers and maybe modulated oscillators for transmit, or much better but expensive equioment. I gather virtually nobody used it, though tyere were a handful of transceivers available.

    Then. CB as we know it came along in 1957, at 27MHz. A bad choice because when propagation was good endless interference from distant stations, but a frequency range where inexpensive but good equipment could be bought.

    Eventually the 460MHz allocation became GMRS and later FRS.

    I am surprised the UK went way up to 900MHz forty years ago. That seems too high for that time period. Even now the ham band in the 900MHz range is barely heard about.

    1. Harry Seyfert, WD9FYF, USA. Thank you for the post. O have visited the UK several times, over the years, but never considered the UK having a CB system. I jave been a ham operator since about 1978. Thanks, agsin.
      73, Harry WD9FYF

    2. I wonder why it never really got used. There was a huge glut of 900mhz devices in the 90s that were inexpensive. Cordless phones and video senders and wireless headphones and such. Then again, maybe that’s why. It seems like anything above 50mhz gets neglected. Maybe because it’s easy to talk a long distance over HF and people don’t want to mess with the higher bands as much.

      1. Until I came across some older catalogs, did I couln’t figure out why low band CB became a thing. IMO it was all about manufacturers creating a new market..Those old catalogs reveal that low band >AM< business band radios where being marketed, that made it easy to to produce radios to serve those, who had a need for two way radios and couldn't afford the process it took to get an assigned a channel, and obtain a license. Yes the government agency played a role, but it was at the bequest of the merchants. Of course that's from a US perspective, I'd have to be surprise, similar didn't occur as other merchant's noticed what was happening in the US, even though the radio of topic didn't appear until about 2 decades later. Even if it' not approved for use today these radios most likely could be used as an IF, combined with other circuitry for use in some ham bands, in the US anyway.

  2. I recall some talk in the ’70s of creating a US CB band around 900 MHZ, using some spectrum that was becoming available that seemed pretty useless. It never happened because the spectrum turned out to be useful after all. (Cellphones and the current 900 MHz unlicensed band)

    1. In tye early seventies the EIA (Electronic Ndustry Association) was lobbying to take the 220MHz ham band and use it for a “Class E CB”. It wouidn’t open up like 27MHz for skip, but wasn’t so high that equipment would be too xpensive. Five MHz was also a lot of space, they proposed a lot of specialty channels. This was of course before the CB boom. 220MHz wasn’t used by hams much, ironically in part because tyere was vurtually no commercial equipment. But it was about when 2M FM was taking off, and solid state meant lots of equioment made specifically for ham use, rather than surplus mobioe tube gear.

      Lots of people saw the proposal as a done deal. The hobby magazines ran articles abkut tye new band, and Electronics Illustrated ran a few construction articles for accessories for the new band. I’m sure there were rigs ready to go into production.

      But it never hapoened.

      1. 220Mhz is a really odd band.
        When I worked for a radio integrator here I came across a pair of really weird 220MHz repeater systems and one downright goofy trunking system that were all basically abandoned due to the high cost of the end devices.

        Motorola made a few radios for 220MHz in their business line, and I knew of a few other brands that listed them but I never saw one in person.

        I think it would make a cool band if paging ever came back though… Kinda sitting between VHF and UHF for propagation characteristics.

    2. I am so glad that didn’t happen. There’s already enough legacy analog junk on the spectrum. Amateur radio and FRS(Because it’s cheap) are some of the only real uses.

      Even police and fire should probably go. If it’s important enough to reserve that much spectrum, it’s important enough to give them some new more reliable digital gear, especially when some places have issues with coverage in buildings and such.

      They should probably still keep a few analog channels around as a backup (Because digital usually works better in general but fails in different ways), but I suspect they could move most of the traffic to digital.

      It’s probably about time FRS officially allows digital voice too.

  3. I remember GE proposing 900 MHz as a CB but with a ID number that you would “dial” first that would unsquelch their radio. What they also designed was that the radio wouldn’t let you listen to traffic just your directed call. It was supposed to be as private as a landline. We all know what would happen. Cell took over, anyway. Scanners had to be blocked, TV’s stripped of the highest channels.

    1. In essence they wanted to use CTCSS with their own tone pairs so they had a filterable radio. This is used this way today but only through bad, flawed marketing talk on PMR446 radios.

    2. Of course, mobile phones had that “privacy” and GE was in the two way radio business. The tone coding didn’t prevent eavesdroppers, but I gather did mean other mobile phone users didn’t hear other people’s calls. There were only a few shared frequencies for the service. It maybe gave a false sense of security.

      There were accessories for CB that did the same thihg. It did keep the user from hearing junk. And FRS walkie talkies today tend to have something like that built in.

    1. 27Mhz AM was all the go in the area I grew up in Australia. I was a bit young so didn’t get in to it till the mid 80’s it was about 5 or 6 years before it died.

      That’s big 10-4 good buddy.

      1. Currently rocking a UHF CB in the car along with my quad band amateur radio transceiver in NSW. Still a better way of getting local traffic reports than waiting for broadcast radio or fiddling about with phones while driving.

        Got a mate at my radio club who was famous in the area back in the day on 27Mhz AM. He occasionally brings in 27Mhz antennas he’s picked up on the cheap and shows us how to mod them for 10 meters band usage.

  4. “The UK CB boom had a surprising effect, in that it brought a whole new audience into radio as a hobby and caused a corresponding boom throughout the 1980s as many of those people went on to obtain their amateur licences.”

    Wasn’t that one of the intentions, official or not, of the CB band? CB here in America served as a low cost entry into the world of radio, whetting ones appetite for more privileges, which would inevitably lead you to an amateur radio license.

  5. Here in Australia we have 477MHz FM… originally 40 channels with a 25kHz spacing and 5kHz deviation, and in recent years they’ve expanded it to 80 channels by reducing the deviation to 2.5kHz and slipping the new channels in between the old ones.

    If you want to learn a whole new collection of swear words, tune to channel 40 during a highway traffic jam. (Look up the Citizen’s Band Radio Service Class License for the frequency.)

  6. I had a Delta 1 for a few years. A GaSFET preamp was de rigeur. My Delta 1 had twenty channels as standard but was modified by the seller to access the full forty. Another “interesting “ mod he included was the ability to scan the analogue mobile phone channels when the microphone was unplugged. Some happy eavesdropping!

  7. I remember my dad had a 23 channel CB in his car. By the time I was old enough I had a radio shack TRC-451 40
    channel rig. I also have in my collection a set of Star Trek Communicators, the blue ones with the telescoping antenna
    that transmitted and received on CB channel 14. I also seem to remember a set of walkie talkies I had that transmitted
    and received on 49.86 mhz AM. I haven’t been on the CB band in decades as I did finally get my callsign in 2003.
    Mostly VHF/UHF/DStar, with an ICOM IC92AD but I sometimes are on the HF bands with a Kenwood TS-430S.
    I remember talking to my dad from the house in Yonkers when he was coming home from New York City.
    Ah to be a kid again……..

  8. I currently have one of those Delta 1’s sitting on the shelf along with a Swiss Stabo that runs 933 and 934 plus a couple of JTi 934mhz handhelds that im refurbing, Co linear up on the roof mainly pulls in cellphone noise but channels 18 to 20 are still clear.
    Although the band closed since 1998 its still used by pirates in the netherlands and uk, with good ranges such as 304km (iirc) into the uk, so hardly just across the street.
    Part of the problem was that users simply didnt understand the critical nature of radio at those frequencies so theyd use the same RG58 as on 27mhz etc and lose all their power before it climbed up the pole and got into the air.
    The radios still pop up on ebay now an again, two went just last week. Interesting to see an article appear on the web about it. :)

  9. I remember reading about the proposed Personal Communications Service (PCS) in the mid-late 1970s. IIRC it was a thing in Japan, and an article in “Popular Communications” magazine speculated about having PCS in America. Among the enticing possibilities that the article explored were number-addressable radios that could remain in standby mode until another radio “called” it, and phone patches for fun and profit. This was before AMPS mobile phone service became available for cars, and so the idea of being able to place a call from a small, high-tech handheld radio was like science fiction. The idea of being able to make a cottage industry out of running a repeater and/or phone patch was also attractive.

    The FCC did create a PCS band around 1900 MHz c. 1990, and there were unlicensed frequencies in the original band plan. But by that time the CB craze was over and handheld AMPS phones were becoming available. I don’t believe there were any PCS radios made for the unlicensed part of the US band, although the licensed portion was used for the first all-digital “2G” direct sequence spread spectrum phone services that started off as low-cost competition to AMPS phone carriers. Because AMPS phones only had two frequency blocks, B for the incumbent LEC (a.k.a. the local phone company) and A for just one competitive service, having the PCS band available for more competitive carriers and technologies allowed the industry to grow beyond the original scope of the AT&T system and become truly personal communications. PCS vendors were the first to eschew the old-fashioned car phone and offer only handsets. While the first PCS handsets were bulkier than the sleekest (D-)AMPS handsets at the beginning, the all-digital voice quality and ability to send text messages (another feature envisioned in the “Popular Communications” article) to distinguish themselves.

  10. Glad to see Brits getting in on the fun. In the U.S., I had, er, heard of someone who had the illegal “freaky freqs” above channel 40 almost into the 10-meter ham band. The conversation cards (QSLs to hams) I saw from CBers were from all over the country even running barefoot 4 watts. There were privately issued “whisky” call signs used sometimes. “Dum Dum Ducky from Monticello Kentucky” sent an elaborate plastic designed card to “a friend” in California. Fun times.

  11. I’ve always loved radio.
    CB and shortwave led to ham radio always something cool there on so many levels.
    Studying for my amateur extra class license right now!

    73 DE N2NLQ!

  12. I would have never guessed to see a CB radio article that surprised me and associating it with a car very similar to my first car. I broke my teeth on CB radios and my first car was a 78 Camaro with a CB in the dash and a toggle switch to push it’s audio out over the radio’s aux jack and mute the radio when keying up (they called it mute but it was more like a quiet mode on that radio).

    Been a long time but could probably still clone an old Cobra from scratch. Have been considering using SDR approach for CB to see how well those two play together. Used to have fun with function generators, little one off circuits and a CB radio. Now that I think about it, probably why I picked up guitar effects as easily as I did when I got into guitars.

  13. Well, 27MHz got benefit of being license-free more or less around the globe and rather good propagation, even through “difficult” areas (remember Friis equation and so on). Though it low tech, low bandwidth (=troble for digital systems) and very hard to get it right with small antennas. And who likes huge antennas for portable devices and somesuch?

    Yet it still used for CBs, some radio control and somesuch. Too bad something like this haven’t happened to other bands at ful extent. Most notably, SRD/LPD/etc are very annoying matter to me: EU mostly uses 433MHz. US uses 315 (and to less extent 390?). Not sure about 868 MHz thogh. There is 2.4GHz but it too crowded, too demanding (=needs special ICs and mad RF engineering skills/expensive measurement devices to get it working on mere FR4) and quite short range/absorbed too much. Sure, some things use it for RC and so on – but not because it good or something, just since it ok around the globe. But world apparently lacks worldwide unlicensed medium freq that ppl can use for experiments and communications in hassle-free manner. Eh, does someone really expects me to become HAM or throw full fledged licensing tantrums just because I want to try to implement some wireless weather sensor and so on? Seems that alone has discouraged hell a lot of experiments.

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