i KNOW NOTHING about CB radio so

[Shayne]

I didn't think they were ever legal Chas i remember an old girlfriends kids wanted one when i was about 16 and i had to set the antenna up in the loft so it wouldn't be seen , and i vaguely remember police luring a bunch of enthusiast to a meet somewhere and arresting them all around the same time . I had a mate who used eavesdrop on police with a spam radio so that was likely the problem . Just looked now and Ofcom only declared CB legal in 2006 probably because the technology is that old it doesn't matter any more .

 

[Chas]

CB's are perfectly legal below a certain power, I think 4watts, it was only the more powerful ones a licence was needed because it was said they interfered with radio/TV signals, but CB use died out because of that. I was about to get one many years ago when that ruling was brought in.

 

[Towpack]

IIRC the illegal CB of over 30yrs ago was 27Mhz AM which was also the same frequency and modulation used by RC models. When CB became legal it was 27Mhz FM (I think there is also a CB allocation at UHF somewhere) and RC model aircraft were allocated 35mhz.

 

[BobMurphy]

Interesting, I'm obviously way out of date now .

Back in the mid-'80s I had a hand-held CB and had a licence (I think it covered me for up to six radios). I didn't keep the set-up for long.

I was surprised that people were still using CB - but I guess its metamorphosed into something more usable over the past 30 years.

Bob.

 

[Shayne]

My CB arrived and either i broke the antenna just dropping it or it was broke in the post , i will never know i guess but regardless i need another stronger better one .

Have done a wee bit of research i believe i want a "top load" flexible antenna ???

Please note Clive needs an antenna to mount on his 80's arb bumper which i will be delivering to him in Romania so i am kinda hoping the same antenna in different lengths will suit both our purposes .

American Firestik is the way i am leaning though i'm searching blind and would appreciate advice .

Here's the CB - Albrecht AE 6110 £48 and the broken Albrecht ministar 27 antenna £17 next day delivery £8

 

[StarCruiser]

Hmmm, probably a bit too cheap on the antenna there Shayne. One with a bigger base is probably better as the smaller ones tend to fall off at speed.…and break off in the post!!

 

[Julian T]

lol break in the post.

This is what I used, with this antenna mounted it where the wing mounted antenna was and then moved it to the winch bumper because bushes when they are trees break it off.

 

[MarkW]

Same whip as me Julian, hit a tree with mine and broke the mount rather than the antenna

 

[Shayne]

That's what happens when you let the seller decide but if he thought that would suit my needs then i suppose i can't go far wrong whatever i buy . So whats the craic with top/bottom/middle load ?

I mentioned i wanted to mount the antenna on the spare wheel carrier between the window and the tyre leaving about a foot above the roof line , he said this will cause interference ?

 

[StarCruiser]

The antenna will radiate through your back window. It will work, but down that low either front or rear mounted would transmit something through the glass.

 

[MikesVX80]

Since when do you need a licence for CB?

Yeah, as far as I'm aware there's no licence requirement for CB radio since 2006: http://www.4x4cb.com/public/page.cfm?Page=643

 

[MikesVX80]

Aerial wise, I've got this: http://www.4x4cb.com/public/item.cfm?itemID=1337

Which is made up of this aerial: http://www.4x4cb.com/public/item.cfm?itemID=2105

And this magmount: http://www.4x4cb.com/public/item.cfm?itemID=713

Sits on the roof of my car, it's pretty tall but the aerial is hinged so you can lower it for car parks and stuff. It's also reasonably flexible so will go through light trees without issue.

 

[clivehorridge]

If you know nothing about CB Shayne, then I know even less

On the antenna discussion, I'd prefer not to buy a broken one... that much I do know

My mounting plate is quite typical, its appx 30mm square (I could measure it but I'm not at the truck right now). That means that a big base would be too big, the one in Julian's post #27 above looks like it would work, or something similar.

Otherwise, I'm relying on your newly developed expertise Shayne....

 

[StarCruiser]

Whatever happens, you need to check the SWR (Standing Wave Ratio) with a SWR meter and get it to read as near to 1:1 as you can by extending or shortening the antenna. If you don't, and you get it fully wrong, all the power your transmitter puts out gets reflected back into the radios output circuitry and you know what Corporal Jones says…they don't like it up 'em!!! So buy or borrow a decent SWR meter for the CB frequencies and fit it between your radio and antenna to check what happens when you key the mic. You only need to do this for setting up. Once it's set up its done unless you move the antenna and put it somewhere else.

As far as power, it'll run happily from the ordinary radio supply which will have a permanent as well as a switched supply. Just make sure you do the connection nicely and don't trap any wires and all should be well. Alternatively you could do like I have and for the small amount I use it, pop a cigar lighter plug on the end of the lead. A more permanent install is better though, just as it stops it flying around the car over bumps.

Nice compact unit BTW. I've used Albrecht radios before.

The PMR radio mentioned earlier, the more powerful one, was probably a business PMR which needs a simple licence for the organisation. So if, say, 4x4 Response UK had a licence, then all the 4x4 groups around the UK could use the radios on 4x4 response business.

 

[clivehorridge]

Whatever happens, you need to check the SWR (Standing Wave Ratio) with a SWR meter and get it to read as near to 1:1 as you can by extending or shortening the antenna. If you don't, and you get it fully wrong, all the power your transmitter puts out gets reflected back into the radios output circuitry and you know what Corporal Jones says…they don't like it up 'em!!! So buy or borrow a decent SWR meter for the CB frequencies and fit it between your radio and antenna to check what happens when you key the mic. You only need to do this for setting up. Once it's set up its done unless you move the antenna and put it somewhere else.

As far as power, it'll run happily from the ordinary radio supply which will have a permanent as well as a switched supply. Just make sure you do the connection nicely and don't trap any wires and all should be well. Alternatively you could do like I have and for the small amount I use it, pop a cigar lighter plug on the end of the lead. A more permanent install is better though, just as it stops it flying around the car over bumps.

Nice compact unit BTW. I've used Albrecht radios before.

The PMR radio mentioned earlier, the more powerful one, was probably a business PMR which needs a simple licence for the organisation. So if, say, 4x4 Response UK had a licence, then all the 4x4 groups around the UK could use the radios on 4x4 response business.

Well, that's all good stuff SC thanks.

Forgive me, but I'm a bit unsure of the legthen/shorten the antenna bit. These are fixed length items aren't they? I'm ok with chopping a bit off it but the reverse? Isn't it a bit like going to the barbers, asking for longer hair?

Im sure I've misunderstood something, although I've read it twice.

Im wondering if Shayne can pick up an appropriate meter, then we can pass it round the group. I'll cover the cost.

 

[StarCruiser]

Sometimes antennas are set to the frequency but sometimes they have a tube with a grub screw in the side that the antenna slides up and down in. You don't need much, just a few millimetres either way and you don't adjust it or touch the antenna while transmitting or (more likely with higher power units) you can receive an RF burn. A bit like being microwaved but only in a tiny way. [emoji6]

 

[clivehorridge]

Aha, thanks Richard, millimeters, I was imagining pruning 4 or 5 inches off with the secateurs

 

[Shayne]

I'm relying on your newly developed expertise Shayne....

Oh great so i get to be the scapegoat as well as the postman i'm still trying to work out why a bloody great lump of metal needs an antenna at all

I get what the Starcruiser is saying about height its like 10mm difference , some allow adjustment and others you just snip the wire after working out were it should be using an old coat hanger in its place , or so i've read .

The SWR i assume is a signal strength reader yes/no ? If so this Albrecht i got has something similar built in i think from what the seller said . Is that likely ?

I like the Sirius antenna Mike posted . My concern was about not getting a signal with more than half the antenna below the roof line but the Sirius is pictured fitted at a similar height to what Clive and i want . As i see it the delicate bit is protected and the wire top should bend quite easy .

So am i barking up the right tree ?

 

[StarCruiser]

Signal strength and SWR are two totally different things. Once set, the SWR should not alter unless the antenna is moved, or has something metal put near it or such like. On the other hand, signal strength can be measured and is about what the receiver 'hears' as well as what it transmits. SWR is the ratio of what is transmitted to what gets reflected back from the antenna. A bit like waves on the sea hitting an object. When waves coming in are 'in phase' with the waves coming back from the object, they cancel each other out. When they are out of phase they reinforce each other and create more power than the waves on their own. Hence setting the SWR of the antenna is critical to the performance of the rig. Not only that, if it's badly wrong it can fry the output electronics in your radio. BTW don't transmit without an antenna connected. They dont like that either.

 

[Shayne]

Right so a tenner for one of them then .