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Is there anyone who has expert knowledge on CB Radios? I have amassed a number of sets and used them with mixed success on runs with Cumbria Group. I could do with talking to someone with expertise to improve our setups. Use has shown them to be an important additional safety feature when working well.

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Well Mark, i was an extremely enthusiastic "Breaker" in my younger years. In fact i still have several sets tucked away in my workshop. My own opinion is that CB Radio has had its day. A hands free mobile phone in a vehicle is by far more superior. I would be interested to hear why you think they would be an additional safety feature in today's world, especially from a motoring view point. Mind you i'm open minded. I did enjoy my CB years.

Noel

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I used them in my MG days. We invested in a three sets and were very disappointed in the results. Reception variable, volume poor and clarity in an open top car on the move was appalling. More of a risk than an asset. After two summers we sold the lot for about 1/4 of what we paid.

 

Never again, I use some good quality digital walki talkies in the mini club with much better results, but the minis aren't open top and volume isn't an issue.

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Hi Mark,

I'm with you on this one. You need a SWR meter and get all your rigs and aerials set up correctly.

You may also find that your rigs may transmit on one frequency and receive on another (just by a tad) so need alignment/fixing. IE can talk be not listen.

The only shop I know is in Bridgenorth - at the other end of the Severn Valley railway.

TRy your local radio club for info.

 

Hi Noel,

mobiles may have superior coverage/clarity etc but you can only speak to one person at a time. As you know with CB you talk to the world in one go.

 

Hi Gary,

as you discovered reception is dependant on terrain. Also the quality of the rig/aerial is most important. The short aerials that stick on the boot are iffy at best.

 

Steve Redway was/is quite an expert on all things radio but he is now incommunicado.

 

Robin Powell on this forum is also something of a radio ham.

 

A few years ago on a shropshire week-end run-out I was in contact with a chap (he broke into our messages from far away) in Evesham (I was about 40 miles away) who was talking to a chap in Ireland about TRactors. Speach was a s clear as a bell.

 

Roger

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Walkie-talkies are cheap to buy and there's no charge for the calls, but range is limited.

I have used them with two in the car on Continental holidays and must have saved a great deal over using mobiles, as calling someone in another British car just half a mile away means an expensive 0044 call when in France or Italy.

Ian Cornish

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Common here in most 4 wheel drives. Line of sight reception and not long range*. But many clubs/enthusiasts have placed 'repeaters' round the place which extends the range quite a bit. You get a few beeps when the signal comes via the repeater.

Also used on the water (marine CB) as the cheapest option for boaties. different set of frequencies.

 

* handy on the long distance outback trips. You can tune into the truckies' frequency and get current information on where the pigs (constabulary) have set up their speed traps.

Edited by littlejim
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Hi Thanks for replies. Our Cumbria Group tends to use the Lake District and Scottish Highlands for fantastic runs but many areas in those parts have non existent phone coverage.The ability to communicate adds fun and safety when someone has an issue or warning to problems encountered ahead. We had one car at the rear on fire in Highlands last year and comms meant immediate help and and a halt to the rest until we established he was OK and able to continue after fettling. The volume issue has been overcome by mounting speakers on dashtop centre behind the windscreen. I fixed the sets with cigarette lighter plugs and magmount ariels so they can be put into a car very quickly. This is obviously a compromise. We have tried hand set held sets without success and the legal issue is grey. C.B. is exempt. The knowledge I need is the best type of Ariel's to use and how to get the best out our sets.

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Mark, i always liked the Thunderpole twigs myself for really reaching out and the firestiks too were good. If you live in the Lake District, the Truck stop in Penrith always had a decent range of Twigs and Rigs. Maybe they still do. The guys in the shop there will put you right on what currently is the favourite set up. I think most decent Truck Stops sell the current range.

.

 

Noel

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Walkie-talkie sets have an earpiece, which the navigator could have installed in his/her left ear, and one can issue a warning tone (usually a selection is available!) prior to commencing to talk. In a TR with top/windows down or sidescreens removed, wind noise can pose a problem, but one can usually slow down!

We used W-Ts on our trip to/from Sicily in a TR4 and a Lotus Elan in 2005, and must have saved ourselves a few quid by not making 0044 calls on mobiles. When needing a pee-stop on the motorways, we would issue the ringing signal, then signal with the navigator's left arm out of the side that a pull-in was necessary! The French autoroutes are very civilised and, in addition to service places, have laybys with decent toilets, fresh water and rubbish bins - often shaded by trees (nice when it's baking hot!).

Ian Cornish

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The most important part of a CB set up is the aerial, both its size and that it has been set up for minimum Standing Wave Ratio (SWR) which may require an aerial tuning unit if adjusting its length doesn't do the trick. You can get combined Tuner/SWR boxes.

 

As Roger says it is better to bolt the aerial base to the car. Mag mounts are OK but don't do as good a job because there is no physical contact between earth and coax outer at the feed point and rely on capacitive coupling to the ground plane. The other thing you have to watch out for with a mag mount is how well will it stand up to wind resistance whilst batting down the continent at 80mph.

 

The performance of the 4 watt UK FM rigs were pretty similar in my experience and the range can depend on radio conditions. Car to car you should get between 1 to 5 miles depending on terrain.

 

I have tried the modern PMR446 uhf hand helds in the car and they are OK in a short convoy but you need earpieces and preferably some form of windshield for the mike otherwise it tend to become unitelligeable. The range is pretty limited car to car.

 

"Something of a radio ham". (G3OGP licensed 55 years)

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Mark

 

I would think that it would improve the performance but you would need at least 3 wires 120 degrees apart and 2.75 metres long.connected to the earth side of the aerial to produce a good ground plane with omni direction.

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I used to play with CB radios a lot in the 80's. Most 4W units can be re-tuned to give more - how much more depends on the make, but most can be tweaked up to around 6W or so. I fitted an extra O/P stage to two of mine which gave me 25W.

However, as Robin says the antenna is probably more significant in improving range than power. Doubling the power will increase the O/P by 3dB,which is about the minimum to make any real difference, but using a good, well matched antenna will give a huge improvement over a poorly designed, poorly mounted, & matched one. For mobile use I found that glassfibre "top loaded" antennas worked very well.

They looked like a fairly normal fibreglass whip antenna (commonly used for car radios back then) they did not need to be excessively long, and because the loading coil was at the top, you got relatively high RF current flowing through the length of the antenna (which makes for good radiation).

Tuning of these was usually by a small screw at the very top, you screwed it in, or out to alter the capacitance to ground of the top of the coil.

Another advantage was that the "sensitive" part of the antenna,ie, the part which would de-tune the antenna if you got near to it, was clear of most objects. RE- ground plane, a good connection to the car body is essential, idealy you would put the antenna in the centre of a roof, or centre of a bonnet / boot. But practicaly most will prefer to mount on a wing, or scuttle. (I had one mounted on the saddle area about 18" from the tank filler - seemed to work quite well).

Some antenna's are designed to work quite well with no ground plane, these are transformer loaded types, where the cable connection is across a 50 ohm tapping of the loading coil. This coil therefore had to be at the base of the antenna, so was not the best for ultimate gain, but did allow easier matching where little, or no ground plane could be provided (e.g. my Reliant Scimitar, being glass fibre, needed such an antenna.) a popular one was called an "Oscar" I had mine on a gutter mount, again worked well.

My longest distance CB chat took place in 1989 while on holiday in France. We had driven into the Pyrenees to admire the views, only to find them covered in cloud, so while waiting for the clouds to clear (they never did) I had a sweep around on the CB. Ended up having a conversation with someone in Linconshire !!

 

Bob.

Edited by Lebro
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Unless these "ground planes" consist of a closely wound coil of fairly thin wire then they won't do anything at 27 Mhz.

A ground plane radial needs to be 1/4 wavelength at the centre frequency, = 2.7 metres.

This can be electricaly acheived in 4" only by using a large inductance (coil) tuned with it's self capacitance to be resonant.

 

Better off using the car body on it's own.

 

Bob.

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Mark

 

Bob is absolutely right about the radials. The vertical section of the aerial should be the same 2.7M length but they reduce it by putting a loading coil in its length which reduces efficiency in proportion to the whip length but makes a more manageable aerial.

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Thanks for info. Looks like the the little pronged things that are sold as ground planes are going to be a waste of time. Should I be earthing the magmounts? Also as most sets are using cigarette lighter socket for power should I be putting additional earth wire to set? I was thinking of using co ax cable for power lead on hard wired sets to cut interference.

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No need to earth a mag mount - the close proximity of the magnet to the car body is good enough

I this is a permanent installation, then yes earth the radio shell to car body, but if a temporary one no don't bother.

 

Bob

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