Club 80-90 Forums

any one know anthing abouy CB's i'm thinking of getteing one for the bus, are there any special problems with haveing a high top.

not if you use a gutter mount

cant see owt in the wiki about radio's

Have a search in syncro, there was a couple of threads recently (Novemberish) with lots of suggestions and useful info.

thanks for that guys, I've been looking on thunderpole they seem to have some good starter kits.

http://www.thunderpole.co.uk/cb_radio_pack-starter.htm

that looks a good deal

Have a look at these guys too.
Very helpful over the phone and have had some great deals in the past. Did me a nice price on a set up for 2 vehicles a while back

what sort of aerial would be better for a high top an orbitor that is 1.55 m or a mini orbitor that is 0.89 or can you sugest any other.

DO NOT get a short antenna you will waste your money....go for longest you can, the antenna is the most important piece in the puzzle
http://www.cbradiobuyer.co.uk/red-thund ... le-antenna
i use one of those for the ham (10m) band and cb, it works well with many contacts worldwide.
if you have a bike rack mount it there. be sure you have a good ground to chassis and you cant go wrong

keep the coax runs as short as possible, use real earth, not cable linked earths.
The T25 is a ideal set up for a interference free set up, with the engine being as far from the cab as it is.Keep the antenna as far from the engine as you can.

The fibreglass hitop will make no difference to the antenna, as long as it isnt painted black.
(some black paint is not rf freindly)

As said above, get the physically longest antenna you can practically fit, with the biggest diammeter open spaced loading coil you can for the best performance.

Fitting a CB to a T25

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.

you should see my 20m whip or the 7 foot firestik on the van. it looks like a dodgem , but that firestik really does work well, cant believe they stopped making them?
with it being mounted on the rear,as you know, its directional. i point the van where i want to work and bobs yer auntie

Thanks for that Mocki, You have answered my next 5 questions that I was about to post. Just one thing do you just put the coax between door and body or do you drill a hole. sorry for stupid question but i am a complete novice and don't want to put holes in my van if i don't have to.

i normally put the coax down the front gutter and in the door below the top hinge, and loop back up to the dash.

no need to drill a hole, if you van is such that you cant mount the gutter mount at the front, and have to mount it behind the door on the "b" pillar area, take the coax between the door rubber seal and the body, just below the radius of the door frame.

Thanks again Mocki.Not 100% sure which one to get but I think the deal from Thunderpole looks the best for a beginer like me. Cheers