CB Radio - Need Help

Right Ladies and Gents,

I am in desparate need of some help with my CB radio. I am fast losing patience with it. The setup:

The transmitter is mounted to the central roof spar of my defender.

The aerial mount is mounted on the roof, to the right behind the driver

I have both a long 5ft whip and a short whip aeriel.

Connected by a 10m coax with PL259 connectors



I try the SWF meter and I am Consistently getting well over 3 (in the red) on both channels 1 and 40. I have tried:

Stripped metal back to bare on mount - No luck

Earth aerial to the body - no luck

Earth aerial to the battery neg - no luck

New cable (again 10m) - no luck

New Aerial (long) - no luck

Run transmitter directly to - from battery

it just reads well over 3 on the SWF on channels 1 and 40, every time.

Am completely at my wits end with it. Only other thing i can think of, is either i have a dodge SWF meter, of there is a nick in the actual transmitter power cable (although unlikely as the tranmitter is powering up and down fine...)

does anyone also know a CB specialist in essex that might be able to help?

Try an insulation chec k on the co-ax cable mate!
The outer (shield) should be insulated from the inner core!!

Get a multimeter and check the resistance (ohms) between the inner cable and outer cable.

Could be a cable fault.

Daz

Defender roof is Aluminium - a poor earth plane.

I had to put a biscuit tin lid (earthed to chassis) under my antenna to get a decent SWR.

Do yu know how to use a SWR meter properly??

Set CB to ch20
Set SWR meter to FWD
Press and hold mic button
Tune SWR needle so it just touches the infinity sign.
Release Mic Button
Set SWR meter to Ref
Press Mic button.


If this still fails. then check swr meters patch cable and get a different swr meter to compare it to.

OOPs didn't realise the roof is aluminium

Daz

Trewey said:

Defender roof is Aluminium - a poor earth plane.

I had to put a biscuit tin lid (earthed to chassis) under my antenna to get a decent SWR.

Click to expand...

That's a URBANE miff. I had a PSM mount on Betty and got 1:1.3 on mine with a 5ft springer antenna

PSM-1 3/8 CB & HAM ANTENNA BODY MOUNT for 4x4 USE ETC. | eBay

I'd no idea CB was still on the go, had one back in the 70's, load of old bollocks back then, has it got any better.

Still got idiots playing music over the channel and guys shouting "oi oi"

Daz

DISCOVERY1-DAZ said:

Still got idiots playing music over the channel and guys shouting "oi oi"

Daz

Click to expand...

.......and Minty singing the 'Convoy' theme tune :doh::doh:

blue beasty said:

.......and Minty singing the 'Convoy' theme tune :doh::doh:

Click to expand...

Brilliant!!!!

That wouldn't get on your tits much!!!

Daz

Johny if ya want you can pop round to me and try my swr meter if ya think yours might be dodgy, I'm waiting on the post for my new ariel, mount and new lead before I can have a go at setting mine up hopefully sometime this week.

DISCOVERY1-DAZ said:

Try an insulation chec k on the co-ax cable mate!
The outer (shield) should be insulated from the inner core!!

Get a multimeter and check the resistance (ohms) between the inner cable and outer cable.

Could be a cable fault.

Daz

Click to expand...

This the most likely problem, although you don't need to check for ohms specifically, just see if there's a connection or not by switching the continuity check on the meter.
Undo the wire from the aerial and the CB, now with 1 lead to the inner pin of the PL259, and 1 lead to the outer body, you should not get any connection, if you do have a connection between the outer & inner, I'd go for the PL 259 not being soldered on correctly, Re-solder it leaving about 3-4 mm of the inner plastic poking through around the inner cable of the coax. check agian once re-soldered.
If there is no connection, then couple the wire up to the aerial and recheck it, if you now have a connection, then you've got the aerial mounting wrong somehow.
NOTE: If the coax from your aerial is not long enough, then you MUST use proper PL259's and a double male connection to add length, under no circumstances just bare the wires and connect them together like you would to extend the power cables etc.
With the aerial on the roof, you should be able to use most any CB aerial, if it was on the spare wheel carrier or lower than the roofline, then you start getting problems with short aerials.

Once you got a reading that's somewhere towards, then to know if the aerial needs shortening or lengthening you can work it out from the reading you get on ch1 & ch40. If the reading is worse on ch40, the aerial needs shortening, if it's worse on ch1, then it needs lengthening. With an aerial mounted on the roof, you should easily get it down to 1.4/1 or better.

The best I ever witnesed was a meet up in Valley Town with CB'rs from Mermaid City. They all met up in a supermarket car park and talked to one another on their CB's.