Cb radio question

[Winchweight]

Hi chaps,

I have just bought a pair of cb radios and aerials from Thunderpole, but have a question.

1 has a magnetic roof mount and 1 has a gutter mount, both stainless steel.

Do they need to have the aerials grounded to the bodywork and do they need to go to bare metal?

Also, those who use cbs, do you use your forum name as your handle/ call sign?

Cheers.

[thebobster]

Mag mount antennae do not need separate grounding to the bodywork. If the roof of the vehicle is steel, the mag mount will work, if it is (for instance GRP) it will neither stick on nor work.

Gutter mounted antennae are grounded through the screws which fasten the mount to the (steel) gutter. A tip I learnt from M0cki's pronouncements on the subject is to mount the gutter mount on the offside of the vehicle so as not to catch on low tree branches etc. The best position for the gutter mount is above the 'B' pillar seemingly.

M0cki is of course the acknowledged guru on all matters pertaining to wireless telegraphy in this club, but there are many other members also who can advise you.

Regarding your 'handle'; you can call yourself whatever you like of course, but in the ''old'' days of CB (70's and 80's) your on-air friends used to choose your handle for you based on what they knew about you. I used to have various handles which depended on which area I was in at the time.

10-10

[Mocki]

Bobs summed it up !

I wrote this some years ago, answers all the questions i think, ignore the bits you dont need!

"The fitting of the CB itself is purely personal choice.
Many of the modern radios are of the correct size to fit in the dash where the ash tray should live, which is the tidiest in my opinion.
As for the connections, straight to the fuse box, or onto the leisure battery, your choice. Do not connect to the Broadcast radio power cables.
Remember tidy cables rarely cause problems RED to +12vdc black to -12vdc. Remember that VW -12vdc is brown, NOT black.

Siting the Antenna

Ideally the antenna should be sited in the electrical center of the vehicle, but unless you have a panel van, this isn’t going to be possible.
HiTops and pop tops have fiberglass roofs, and radio doesn’t “see” fiberglass, it is nonexistent so drilling the roof, or bolting to the fiberglass is not an option, it simply won’t work. The antenna mounting must be electrically connected to the metal body.
Most T25 owners opt for a gutter mounting, which ensures a solid and well grounded connection to the bodywork. If you have “syncro2 or LT” style mirrors you can opt for a mirror mounting bracket, but you will have to remove or bypass the rubber mounting from the mirror arm to get your electrical connection to ground.
Either gutter or mirror mounting should be on the RHS or off side of the vehicle, keeping the antenna in the center of the road, and thus away from low tree branches and other obstacles on the nearside of the road.
Gutter mounting.

If you can buy a stainless steel gutter bracket, rather than a cast alloy one, the stainless brackets are much stronger and more robust.
The gutter bracket should be sited on the gutter just behind the front door, inline with the “B” pillar on later model vans (85 onwards) as the door gives less clearance at the gutter on the later vans and the mount will foul the door top. Early vans should be ok at the front corner of the front door, at the “A” pillar.
Ensure the grub screws penetrate the paint and sealer as they bite into the gutter ( you can paint of seal this over after installation) as you need this ground connection to be good. Once the mounting has been securely connected to the body the coax needs routing into the cab, and the easiest most effective way to do this is via the front lower edge of the door, at the end of the gutter strip that runs down the window screen, and into the cab just above the top hinge of the door, up and under the dash, making sure the coax cannot be snagged by the feet of the driver of passenger. Safe tidy cabling is the way to go.

Tuning and SWR

Most antenna systems these days are “pre-tuned” and require little of no tuning.
However if you have access to a SWR meter, it is best to check. Should you need to make any adjustments, the procedure is

1. Connect the SWR meter to the CB, via a “patch lead” and then the antenna to the SWR meter.
2. Set the “FWD-REV” switch on the meter to “FWD” select ch40 and transmit by pressing the microphone PTT switch.
3. Simutaniusly turn the |SET\ control to the infinity mark at the right hand side of the meter scale,
4. Release the PTT stop transmitting
5. Move the |FWD-REV” switch to the “REV” position, and transmit again, the needle on the scale should now read ideally below “2” but anything below “3” is ok.

Select channel 01 and repeat steps 2-5 and compare readings, should you need to adjust the length of the antenna, these are the simple rules.
If the SWR is high on a high channel (40) and lower on a low channel (1) shorten the antenna
If the SWR is higher on the low channel, and lower on the high channel lengthen the antenna.
Only move the tunable section 3mm at a time checking with steps 2-5 each time.

SWR is Standing wave ratio, in layman’s terms, the amount of “feedback| of transmitted power trying to return down the coax to the radio reflected by an ill tuned antenna.
All but professional mobile antennas will be electrically 9ft long, but physically much shorter ( the difference being made up with a loading coil or spring at the base or center of the antenna – the longer the antenna is physically the better. Coils are inefficient, so the less of that 9ft that is coiled up the better.
antenna"

[Winchweight]

Brilliant, thank you.

I also have a stainless steel mag mount for the T4. It has a thin rubber cover, should is remove it to get a metal on metal connection?

[Mocki]

No, magnetic mountings use magnetic field as earth, no actual electrical connection to the body is needed.

[Winchweight]

Thanks again chaps. I'll be playing tomorrow.

[ghost123uk]

I also have a stainless steel mag mount for the T4. It has a thin rubber cover, should is remove it to get a metal on metal connection?

Hey, Winchweight, were you going to scrape a circle off paint off your roof (just joshing )

May I emphasise what Steve said about painting a bit of decent paint over where the 2 clamping screws "bite" through the paint and in doing so "earth" the gutter mount to the body. If you do not do this you will very soon have rusty holes in your gutter Therefore do it straight away after fitting the mount, as rust can start to take a hold within a few hours, especially in damp conditions.

When you have them up and running, don't be surprised if all you can hear is each other. In my experience, in recent years, one can drive around for days and not hear another CB user. I believe CB usage varies from place to place. Last time I went to Sheffield there were lots on the air.

Re those black cast "alloy" gutter mounts. They used to make decent ones (when I had the CB shop in Chester ) but now, like so much other tat that comes do doubt from China they are made of monkey metal and break if you tighten the grub screws up enough to get a solid fit I have gone through 3 in the past year or so But I have 2 aerials, one on each B piller (one is a hi-gain broadcast radio aerial). The main pivot bolt and the 2 Allen grub screws go rusty too, so some black paint on the exposed parts of those will keep it looking pretty (until it breaks).

[Winchweight]

Thanks Ghost. I bought them mainly for use at events, or when we have our two vans in convoy.

I bought the stainless steel mag mount and gutter mounts.

Cheers

[pionte]

I fitted a CB for the trip down to Busfest last year, Mocki kindly checked the SWR meter reading for me.

All the way there and back I think I heard 1 other person on ! I have left the aerial on as I like the retro look,



but I hardly ever bother to put the radio into its cradle, unless I am going in convoy somewhere with friends, then I give them my 40 channel hand held for their car, as they are reluctant to screw great big aerials and radio units to there new shinny cars

[Jim San]

! I have left the aerial on as I like the retro look,

but I hardly ever bother to put the radio into its cradle, unless I am going in convoy somewhere with friends, then I give them my 40 channel hand held for their car, as they are reluctant to screw great big aerials and radio units to there new shinny cars

There is something about the look of a big whip on a 4 x4

I've considered the handheld option as i dare say mine would only get used for events - but then i'd not have the aerial

Its on the list Winchweight, i'll talk to you
its not high on the list of priorities though mate, plenty of other stuff to fork out on first,

i'll use jim san as my handle, i wont resurrect my handle from days of old

[jokeruk]

Further to this - how many people have Amateur Radio licenses? (i'm M0NEX for those that have)

[Mocki]

m0cki

[Winchweight]

I don't and unless I'm missing something, as of 2006 there is no requirement to have one for CB usage, provided the regulations are adhered to.

http://stakeholders.ofcom.org.uk/spectr ... and-radio/" onclick="window.open(this.href);return false;

[ghost123uk]

Ah, you misunderstand. The question was meant to enquire as to how many on here are "fully fledged" amateur radio operators with an amateur radio licence. You don't need one to operate a CB radio though you do for 2Mtrs, which is very similar ha ha

[phredd]

G0RBM ......... qthr