CB antenna advice please!

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AdamD1

AdamD1

Well-Known Member
Posts
682
Location
Essex
I have a couple of cheap CB radios sitting at home to fit to my D1 and a mate's navara. I've looked online but I can't find anything that makes any sense to a noob like me so perhaps the fine people of LZ can help me out? We don't need huge range, just to stay in touch while travelling on and off road.

I'm not too desperate to drill any holes but if I have to so be it. Would be helpful if they could be unscrewed when not in use.
 
These are quite good short range. Range can be increased by opening a window :)

red-megaphone2.jpg
 
I've never had one of these new fangled D1s but I understand you can use a mag mount due to a preponderance of steel.....provided tin worm hasn't had it all away yet.

Antenna cable should slip under door seal without too much trouble I imagine.

But then again some of the things I imagine don't stand up well to scrutiny.

I'll move the fred to somewhere you might get sensible answers :)
 
If you're not particularly bothered about range, then all you'd have to worry about is the tuning or SWR. Most CB aerials, particularly the shorter ones with "loading coils" in them tend to be pre-tuned these days and can just be connected up and used with few adverse effects other than a reduction in range.

If I were you, I'd check first with a magnet to see if the roof of your Disco is steel or aluminium, my Disco 2 bodywork is part steel and part aluminium; the roof is steel. If yours is also steel then a magnetic base or "Mag-mount" aerial will do the job. The aerial I've show isn't too tall so it can go on the roof and it's pre-tuned so you won't have to get involved with Voltage Standing Wave Ratios (VSWR), it's more or less plug and play.

http://www.ebay.co.uk/itm/CB-ANTENNA-MAGNETIC-MOUNT-CB-1000-VAN-TRUCK-ESTATE-27MHZ-STRONG-MAG-QUALITY/171780999731?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D20140122125356%26meid%3D7207a638d768407f9c7c274d4bdd4d09%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D161687781979

It's very similar to the one that I have and I don't have any VSWR problems with it.
Obviously, if you can find somebody with a reflectometer (VSWR bridge) and the wherewithal to use it then fine tuning could marginally improve performance.
 
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Looks pretty ideal thanks, the tuning was the part that was scaring me off. Not in need of ultimate performance, just something that works a little better than the handheld walkietalkies.
 
The fear or misunderstanding of Standing Wave Ratio is one of the things which makes RF sometimes referred to as "White man's magic", and there have been many myths written or spoken about the subject.
As @blue beasty has said, a bad set up with a high VSWR could lead to damage to the RF output transistors, although in 40 years I haven't seen to many transmitters damaged in that way, many modern transmitters tend to have systems which shut down the power until the fault is cleared.
In the case of a mag-mount aerial, obviously there is no apparent or direct connection to the vehicle ground and this is taken into account during manufacture and initial tuning. The only condition which could cause an excessively high VSWR would be a damaged aerial feeder cable. In the case of a new aerial and factory fitted feeder, the only risk would be where it's fed through a door seal.
If you do have access to a cheap reflectometer, then yes, do a check. Anything better than a reading of 2:1 can be considered as satisfactory, however if the VSWR shows over 3:1 then damage could be a result. If your reading is 1:1 then although that might sound like perfect tuning, I would suspect an aerial feeder fault; nothing is that perfect in this world.
Untitled.gif
 
I didn't actually realise people were still using CB radios.
Is there a practical use/need or just the fun of playing around with some older kit?
 
chris-the-gerbil said:
Licence free, cheap and effective for talking to people when greenlaning. I have one in mine as well as PMR and some amateur gear for longer range comms.
Click to expand...

As @chris-the-gerbil has said, CB is cheap and useful when greenlaning or just a group of friends travelling in convoy. It can also be very useful if you're towing, saves having to try to communicate with the driver being towed using hand signals. Unlike mobile phones, it's not illegal to use CB or PMR kit while driving, the only thing is to avoid "driving without due care" charges.
The PMR446 kit can also be useful for the same reasons, however much of the cheap imported kit should be retuned to meet the UK frequency standards.
I find the Baofeng UV-5R is quite a good piece of kit, it can be tuned for use on the PMR446 frequencies, the amateur 70cms band, the marine VHF band as well as the amateur 2 metre band.
I don't carry any dedicated amateur gear these days, although I do still have an old 2mtr Pye W15FM dash mounted Westminster somewhere.
 
Dont think it's actually legal to use the Baofeng on PMR... bit overpowered lol.

Pye oooh now you are talking. I had one of the ones that had the telescoping ariel that would go up your nose if you were not aware what on earth was the model number? Not the pocketfone it was another one...
 
chris-the-gerbil said:
Dont think it's actually legal to use the Baofeng on PMR... bit overpowered lol.

Pye oooh now you are talking. I had one of the ones that had the telescoping ariel that would go up your nose if you were not aware what on earth was the model number? Not the pocketfone it was another one...
Click to expand...
You can reduce the power while you're in the tuning data on a PC, but to be honest, I can't see plod stopping you and telling you that you're transmitting too much power and he's going to prosecute you for it.
If you're thinking of the little UHF transmitter which had the spring loaded pop-up aerial, it was a pocketfone; the PF1 which was the first one that Pye brought out, the transmitter and receiver were separate units.
I spent many (un)happy hours working on those things, first on the bench at the Cardiff workshop for Pye and then on the pocketfone bench when I was with the Home Office. I was able to take many of the manufacturer's un-published tricks with me when I went there.
 
Chirp lets you drag it down to 500mW? Not tried that I must confess there is still type approval of course but I think you can more or less ignore that if you can show spectral cleanliness. Whilst people lambast Baofeng they are actually pretty clean on UHF accoding to my analyzer its 2m they tend to go a bit loopy on.

It was the pocketfone yes I've just found some pictures of it, with the two units. It's scarey how big things where, or rather I suppose it's amazing how small they have become..:) When you look at my FT101 and my IC7000 it's an incredible difference....
 
chris-the-gerbil said:
Chirp lets you drag it down to 500mW? Not tried that I must confess there is still type approval of course but I think you can more or less ignore that if you can show spectral cleanliness. Whilst people lambast Baofeng they are actually pretty clean on UHF accoding to my analyzer its 2m they tend to go a bit loopy on.

It was the pocketfone yes I've just found some pictures of it, with the two units. It's scarey how big things where, or rather I suppose it's amazing how small they have become..:) When you look at my FT101 and my IC7000 it's an incredible difference....
Click to expand...
It was surprising at how small they were really, considering that they were all discrete components, not a single IC in sight and the tuning was done with proper old fashioned LC lumped circuits. Working on them wasn't easy, everything was packed in so tightly. The bulk of the transmitter case was taken up with the 18 volt Ni-Cad battery and the mechanicals for the pop-up aerial. The receiver was a proper double conversion superhet too, 10.7Megs and 455khz.
 
Dredging back to memories Id rather forget they had all the components on little boards that where then soldered at right angles to the main backplane or something. I seem to recall lots of mica sheets too for insulation? I liked the receiver though I converted one with a tweak up on the IF and it did a great job listening for the down conversion from my 3cm receiver. :)
 
chris-the-gerbil said:
Dredging back to memories Id rather forget they had all the components on little boards that where then soldered at right angles to the main backplane or something. I seem to recall lots of mica sheets too for insulation? I liked the receiver though I converted one with a tweak up on the IF and it did a great job listening for the down conversion from my 3cm receiver. :)
Click to expand...

That technique was used in the pocketfone PF2, PF5 and the pocketfone 70. It was also used in the Burndept hand portable used by the police. the PF1 actually had a single board with the components soldered directly on it, no "daughter boards". The plastic insulation was Mylar which was folded and inserted between the little boards in the later sets in a sort of maze, get it wrong and you could be there all day.

I've found a couple of pics of the PF1T and PF1R so you can see what I mean:-

IMG_0008a.jpg


The tx board, solder side
013c52e85bd55714a79f8c23659e3bb5_PYE_PF1-T_4.jpg
 
They look familiar.

Digging throung my collection it turns out that the one I used for a 3cm down convertor was in fact the one that looks like a giant shaver with the angled top. I've got bits of at least two PF2 and no idea what that was built into! Somewhere there is still an unmodified PF1 in the original box but I'll be stuffed if I know where. I suspect that they may be starting to be worth serious retro money now...
 
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