Thursday, October 23, 2008

CB Radio Memories

My first contact with CB radio was in 1977 when I was given two single channel CB walkie talkies by a relative from Canada who was visiting us.
Having walkie talkies was a very exotic thing in the UK at that time when radio regulation was very strict, and they were used in many childhood games of secret agents and cops and robbers.
The radios had a single channel on 27.125 (channel 14) AM and 100 mw of power output. The range was about a quarter of a mile and on two noteable occasions I managed to make contact with other people! The first time was when another boys voice answered me back from a street quite a distance from ours and we ended up meeting up half way. The two gangs with the walkie talkies. The second time was with a motorist in a nearby car park.

What I did not realise at that time was that channel 14 was not used as the calling channel where I lived in Stirling. For some reason they used 16 and this is why I wasn't hearing as much as I might have. Various reasons have been given for the choice of 16, but the one I like best was that in the days of 23 channel crystal controlled radios one of the locals had a bad channel 14 crystal so everyone moved to 16. Another possibility was that they were trying to avoid us kids on our channel 14 walkie talkies.

The walkie talkies moved my interest in radio, which already included listening for exotic stations on medium and short wave radio, towards transmitting. I started getting amateur radio books out of the local library and went on to study for my radio amateurs exam. I got my licence at the age of 15 in 1982, but before this CB had been legalised in the UK after a campaign by existing users of illegal equipment.

Round about 1980 I came across a protest demonstration in the nearby Kings Park with people speaking from the bandstand and lots of cars with aerials on them. It was part of the campaign to legalise CB. I am pretty sure that one of the speakers went on to become a prominetn local radio amateur and a good friend of mine but my memory may be playing tricks.
I scooted about on my bike listening to all the traffic on my single channel radio.


The legalisation of CB in the UK
CB was finally legalised in 1981 but using 40 channels at the top end of 27MHz which meantt he illegal US equipment was not compatible. At the timne various celebrities promoted the use of CB including Tony Blackburn and the Lord Provost of Glasgow, Michael Kelly, who had a CB radio fitted in his official limo so he could "talk to the people" as he was driven through the city. Incidentally, CB was officially called "Open Channel". Eventually this was changed to "Citizens Band Radio" because thats what the public called it.


Equipment
When CB was legalised in 1981 none of the illegal equipment would work on the new channels so there was a rush by manufacturers and retailers to get radios on the market. The craze became so large that you could even buy a CB radio in Boots the chemist. When the boom broke, Boots sold off York CB's for £10 each, like many retailers who had to dump stock to get rid of it. COmet eventually sold the Amstrad 901 for £20. Prices had originally been much higher. I worked in Dixons in 1984 when they were clearing out their stock of Harrier CB's at 50% off (£50 for the base station which was normally £100). At this time a few radio amateurs bought cheap CB radios for conversion to 10m. The Cybernet boarded radios were quite difficult to convert requiring an expensive additional board, but the LCL, DNT and Icom 1050 could be converted more easily. The Icom 1050 was a bit cheeky as it was not made or sold by Icom, but was someone else cashing in on their good name. SMC also marketed a CB radio called the Oscar, which they also sold in a 10m version. The reason for this interest in converted CB's was that most amateur radio HF transceivers did not have FM at all or required expensive FM boards fitted. Even if they were fitted they did not have the repeater shift for operating through the european 10m repeaters. It was possible to add the repeater shift to some of the converted CB radios and the SMC oscar had this on the switch normally used for high/low power. CB operators sometimes added a channel zero which was 10KHz below channel 1 and was considered to be more private (but illegal).

Harvard and Harrier radios were very similar and I can explain why. Harrier was Dixons own brand and had previously been used on their airband radios. Dixons actually had a sales caravan that toured air shows selling cheap airband radios and binoculars. Binoculars had a very large profit margin and they did very well from it. Harvard was a brand marketed by Harris Overseas Ltd. Harris eventually bought Alba and they now operate as Alba Radio. They also own the Bush and Hinari brands. In the early 80's they were sourcing CB radios from the far east and Dixons sourced their radios through them. The Three radios in the Harvard and Harrier ranges were identical inside and only had cosmetic differences on the outside. Harvard radios were sold through various retailers, but most commonly Comet.

While I am talking about radios I should point out the similarity in the ranges of all the manufacturers at this time. usually they had three types of set with progressively more features.

1. Basic set with volume, squelch, high low power switch. (e.g. Rotel RVC220)
2. More advanced set with the addition of CB/PA, tone and mic or RF gain controls (e.g. Rotel RVC230)
3. Top of the range with controls like delta tune which allowed you to communicate with people using US style multimode radios (e.g. Rotel RVC240)

If you open up these radios you will find the same board with extra components for the additional features. Some of the features are of little real value such as RF gain or Microphone gain.
The receivers and transmitters were identical across the different models in the range.

It was also possible to buy CB handheld radios which were the size and weight of bricks, took 10 batteries and had telescopic antennas 1.5m long. We often sold pairs of these to skiers. I often wondered how long the antennas would last on the ski slopes.

One of the biggest problems with most of the CB radios of that period was poor receiver selectivity with adjacent channel interference (known as bleedover) being a problem with many of the cheaper radios. The Home Office specification was mainly concerned with reducing the risk of interference and did not have a specification for selectivity. Some radios could be improved by fitting different crystal filters, but the root of the problem was the narrow 10KHz channel spacing with the relatively wide FM modulation type. If a transmitter had the deviation turned up too far or a receiver had poor filtering then the signal could be picked up on adjacent channels. This is one reason why radio amateurs used 25KHz channel spacing on FM and commercial PMR radio used either 25 or 12.5KHz spacing. 10 KHz was a technical obstacle. Eventually the government revised the CB specification to tighten up receiver specification and most modern CB radios do not suffer from these problems.



Antennas or aerials (as we call them in the UK)
The quarter wave whips (often mounted on the bumper) were around in the 70's and 80's but eventually gave way to loaded whips. The standard mobile antenna early on was the DV27, a fiberglass top loaded antenna with a handy tuning tip. These actually performed very well and because they were light and the bases had a tilt on them they were easy to fit to most cars. Eventually other antennas became popular like the K40 base loaded antenna then the half breed base loaded and the modulator type (with a larger base loading coil). The firestick antennas were also popular especially with truck drivers but they needed a good solid base.

Most base stations used the half wave "silver rod" antenna with some going for the larger Sigma 4 which was a three quarter wave vertical. The CB regulations at the time required no antenna to have a radiating element of longer than 1.5m which made these antennas illegal. Also if the antenna was above a certain height the power had to be reduced by 10db which was the reason for the high/low power switch on the radios. Of course lots of people ignored this and some manufacturers even made antennas that looked loaded which were actually longer than 1.5m, the support pole actually being part of the antenna. There were some loaded base station antennas that became popular like the Thunderpole which had three radials positioned to try and get a lower angle of radiation from it for increased range.

DX operaters on SSB would sometimes use yagis or delta loop beams (I think a model made by Avanti).


Amplifiers
RF amplifiers (known in CB language as "burners" or "boots") were not that common where I lived, but people who had them tended to use them in the car to increase range a bit. Home users often opted for the valve amplifiers by Bremi and Zetagi that used PL509 TV valves. This was because high current 12v power supplies were expensive or hard to get and it was cheaper to use a mains powered valve amplifier. The problem with CB amplifiers was that they were suually class c, not linear and if they were putting out 100w you could never be sure how much of that was actually on 27MHz rather than its harmonics.

934 MHz
When CB was legalised in 1981 there were a further 20 channels at 934 MHz which was real cutting edge territory at the time. Equipment was very expensive and it worked best in flat areas which is presumably why I don't remember anyone near me every having any equipment for it. This service was withdrawn in 1998, ten years after the last equipment had been made for it and the frequencies were sold off to mobile phone companies.


The end of the craze
The problem with CB was that it went from being a fairly popular hobby or communication tool to the must have Christmas present. The resulting over supply in the market meant that anyone with £10 could pick up a discounted radio and begin a career as a narrow band FM DJ. The other problem was that the launch of CB coincided with rising sunspot activity and interference coming in from Europe made 27MHz unusable a lot of the time. Although we have seen a recent increase in CB activity since deregulation in 2006, the pending move to the CEPT frequencies in 2010 could mean that interference is even more prevalent during the next sunspot maximum. This could kill CB stone dead. At least the UK channels did not coincide with the legally used ones in Europe where most of the interference was.


Other bands
As well as legal 27 MHz and 934 MHz there was illegal activity between 26 and 28 MHz (known as freeband) and some rare activity on 6.6MHz and 3.4 MHz using converted amateur radio equipment. I did not know anyone involved in this, but even today there are occasional nets on 3.4MHz (known as the 85m band) around the north of Scotland.



American culture, secrecy and the lingo
Because CB was illegal in the 70's it was not safe to give exact names or locations. Amazingly, this still continues today. I was told off recently for saying what street I lived in so someone could find my house, yet my details are published in the amateur radio call book. The other thing which went along with this was the use of "secret" codewords, 10 codes and slang. For example Stirling was "silver city" and Kilsyth was "dry town" (referring to the fact it was one of the last places in Scotland to have pubs). The 10 codes were not used in their original meaning. For example 10-10 originally meant "fight in progress" but was changed to mean something like "goodbye". 10-100 originally meant "dead body discovered" but this was used to refer to going to the toilet.

Part of the attraction of CB was the popularity of southern US culture typified by CB, truck driving and country music. Films like Convoy, Smokey and the Bandit and TV shows like the Dukes of Hazzard made CB identified with working class people doing things that were borderline illegal and getting away with it. CB in Britain became a cultural phenomenon rather than a communications tool.


Impact on Amateur Radio
The impact of CB on amateur radio was generally been positive, with more people being exposed to radio communication in the pre mobile phone days. Many of the older illegal users got fed up with CB and moved on to Amateur radio causing a big influx of new amateurs in the early to mid 80's. As time has moved on there is much more crossover and while I am primarily an amateur radio operator I do use CB radio for informal family communication because anyone can use CB without needing a licence.

The Future
There has been a definite increase in CB activity since licencing was abolished in 2006 and it has got a bit of a following amongst off road enthusiasts. Also, the launch of PMR 446 has sent some people in search of radios with greater range and some of them have ended up on CB. The risk, of course, is that with the sunspot maximum approaching the band may become unusable. There is also the risk of some sort of clamp down on the use of CB 27/81 radios when those channels are withdrawn in 2010. Although there have been 80 channel UK/Eu radios on sale for ten years there is still a lot of CB 27/81 equipment in circulation.

2 comments:

  1. Is 27/81 still legal? I am not sure if it is still allowed. Just heard at least 6 people on in the lincoln area tonight when I dug out my old fm cb.

    ReplyDelete
  2. I think it is legal for another year or so, but most radios sold in the past few years have the European channels as well.

    ReplyDelete