Tuesday, October 14, 2008

What is the range of CB radio?

Having used CB recently for family communication it seems that a reasonable reliable range is:

Base station to base station with proper antennas : 10 miles
Car to car with medium sized antennas : 2 miles
Car to base station : 5 miles
Handheld (with helical antenna) to base station : 1 mile

This refers to UK CB radios (FM, 4 watts output, 27MHz).

Range can be more than this but if you want to communicate reliably this should give you a guide to whats possible.

CB radio in the UK no longer requires a licence and can easily be fitted in a car using a magnetic mounted antenna and a connection to the cigarette lighter socket.

6 comments:

  1. I have just purchased a kit with CB and antenna from Maplin. I have discovered that my range appears to be a 1/4 mile. Which frankly is pants! The CB is made by company called TTI and the antenna is a stinger (Errr....it has a spring at the base, think thats a stinger) on a mag mount. I have it on the roof of my Navarra and have the CB into the cigarette lighter. Do i need to tune the aerial? Or are Stingers generally pre-tuned?

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  2. Hello Steven. You should be doing much better than that. I don't think those antennas are tuneable, but it would be worth checking the swr on it with a meter. As a rule of thumb an antenna needs to be about 1.5m long (at least) to work well on 27 MHz. The stinger type antenna comes in long and short versions. if you have the longer version then I think you may have a tuning or installation problem. It is unlikely to be a radio fault. Hope that helps.

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  3. Hi Gordon,

    You wouldn't believe it, it's hard enough to write down. After 3 weeks of tinkering with a homemade vertical dipole, 28ft up and still only getting an SWR of 3, I finally cracked and bought myself a Long Stinger whip about 1.58m long with a gutter mount for car fitting. The guy online said it was totally the wrong antenna for me, but I liked the look of it and I couldn't see why it shouldn't work as a garden mounted 9ft high antenna. Admittedly, I do live in the middle of a wood, surrounded by 40 ft pine trees, but hey I like a challenge ...

    I got the antenna yesterday lunchtime and I thought that I would try it mounted on an old alloy speaker stand that I had lying around. It had a small flat base table (approx 10 inches square) to use as a ground plate and I ran a short piece of cable from the earth below the antenna down to the leg of the stand. I switched on and I was amazed that I had an SWR reading of 2.8 ... already lower than all of my previous dipole readings.

    I was stewing, because I new it could do better. I read some stuff online about biggest ground plates and materials to use, but one article caught my eye. This guy had built a 1m x 1m plate out of aluminium and had bolted it to an aluminium ladder as a rock steady base. He reported great results. I thought that I would give the ladder a try and see how it was without a groundplane ... and I'll tell you what ... I've got a convenient, mobile, non-obtrusive garden mounted antenna with an SWR reading of 1 ... Hallelujah !

    I couldn't believe it when I saw it the first time, but it works absolutely great. From my little place in the woods I'm talking to CB'ers 22 miles away as clear as a bell (they say I'm pumping 7 bars from my un-tweaked machine). They all tell me I'm crystal clear and good and loud.

    So, if you're thinking about fitting your house out with a massive dipole and you've got an car mount antenna in a box somewhere ... try this first.

    All the best

    Colin (Norfolk)

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  4. I am not surprised. Part of the secret is getting something thats in tune and out in the open. Often a shorter antenna will beat a longer one under these circumstances.

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  5. what is best am 4 watts or fm 4 watts as it is comimg legal in july 2014 thanks allan at wigan greater manchester

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  6. AM doesn't suffer from capture effect so one signal will not obliterate another one. This means that range can be greater, but it may not be as clear. The limit is "ground wave". 20 miles by ground wave would be pushing it. Reliably 5 to 10 miles. That's based on my experience here in Scotland, but we have mountains.

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