CB Radio

WE use the tti TCB=560 its very small been in use over 3 years .

AND Happy 40th CB day 10-4

That does seem good price.  I have a full DIN sized CB in my Jimny, slotted in above an aftermarket stereo for tidiness.  But I do like the Albrecht one, it's not far off the size of a cigarette packet, can be tucked away easily.  

moonrakeronline.com/albrecht-ae-6110-min...dio?___store=default
 

ls CB still a thing? l had a rig back in the 1980's but l thought it was dead now.

My erm, handle was Zero-X

Yes CB is a thing, and very busy on 19 , and 25 and 34 , I do a lot of QSK ON 25 all over the UK

Currently in the process of hooking up a CB to my Jimny. Can't get the SWR down below 3 at the moment. Seem to have a decent ground (tested with separate ground strap), cabling all ok and tried two different antenna. Think it might be a dodgy mount, so waiting on a new one to arrive.

Thanks for the reply Martin, yes I'd tried everything to no avail. Have now fixed it and it seems to have been the location of the mount.

I had bought one of these backets from Jimnystyle, that sits on the rear door hinge.

 

I tried it with two different mounts attached, (Thunderpole Powerstick, Thunderpole Chrome) and using two different antenna (Thunderpole Mini Orbiter, Thunderpole 3ft powerstick) but no matter what height adjustment I made the SWR sat in the 'danger' zone on the meter. Both mounts had a good ground (checked continuity many times) and no shorts in the various cables.

I ran out of time to fix the problem before my recent trip to the Yorkshire dales, so had to rely on the tiny rubber duck aerial on my Midland 42DS, which gave me a range of about 100m!

Bought a magnetic mount when I got home, slapped it on the roof today and POW! perfect SWR on all channels straight away. Can only assume that having the antenna sat halfway down the back door meant that a lot of the signal got reflected back. Seems like the Jimnystyle bracket (and APIO bracket that they copied) are only good for looks, not function. Wish I'd known that before I spent a small fortune trying to fix it! 

If the active part of the antenna is not in the clear above the back of the Jimny then the back door will detune the antenna and give you a poor SWR.

Another problem might be the ground plane, the antennas you have used might want to sit on a good ground plane (centre of the roof) or you might have a poor earth if it is through paint, both of these could detune the antenna and give you a poor SWR.

Antennas are balanced and have two elements, like a dipole, but if you don't have the other element (all whip antennas are like this) then using a good ground plane acts like a mirror and gives you the other element.

Thanks DrRobin, I know little about antennas. The earth on the bracket was good, I ground it back to bare metal and had continuity between that and a known-good ground point elsewhere.

I tried the second antenna as the first was listed as being 'baseloaded' and like you mention, I was worried that the location would prevent it working properly, but had the same issue with a 'topload' as well (although having subsequently read further, it doesn't sound like that means that all the signal comes out the pointy bit as I'd assumed!

I think it was the lack of a good ground plane that was the big issue. Plonked a 5" mag mount with the Mini Orbitor on the roof and the SWR needle barely moved, whereas before it was flinging itself to the right!

I should probably have gone mag mount to start with, as I'll only want to use it once in a blue moon and having the MIdland 42 with car kit means that the whole setup is easily removable.

Base or top loaded refers to where the matching coil is located. The antenna has to be resonant length on the frequency you want to use and CB is near enough 10m, so a 1/4 wave antenna is 2.5m.

The loading coil (base ot top) makes up the difference in length between the antenna and 1/4 wave length, but the coil doesn't radiate, it is the rod or element that radiates.

If the radiating element is very close to a metal surface, the radio waves are reflected back in to the antenna and this gives you a high SWR.

It's a pity as it looks like a really nice mount, the only solution would be to fit a short pole on to the antenna to get the radiating part above the back of the vehicle. Or use an antenna with a long part at the base that doesn't radiate.

Robin