CB SWR???

[MattHaworth]

Hello,

Finally fitted my new CB after the old one got stolen. Same problem is that I get no signal. Bought an SWR a day before the old one got swiped so never got to find out what was wrong. Have the same problem although now I don't know if the SWR meter works or not. The needle doesn't budge unless you shake it, I soldered a new plug onto the cable as they just cut the old one.

I have a 3" Stinger aerial mounted onto the back of the truck, a metal plate to secure the aerial bracket on the inside, a rubber grommit that goes to the larger diameter bolt, the cable has a large cable and a smaller (earth I think) cable that fix onto the prongs attached to the aerial mounting bracket. Everything appears to be correct but It just doesn't work. I live very close to the A34 so thought I'd be able to pick truckers up on channel 19 to see if it works. Nothing. Anyone suggest whats wrong or live around Oxford that could help me out?

Thanks

Matt

[bananahead]

I think you can get pre-swr'd airels..

You tried one of them?

Oh and im not sure how these things really work but if it is an earth... is it bolted to an aluminium body panel?

Will this affect it?

[timbott]

Do you have a multimeter or some means of testing continuity? If so make sure you ain't got continuity between the inner and the outer of the coax for starters.

Sounds strange that the swr meter doesn't move though:confused:

cheers, Tim

[MattHaworth]

Thanks guys,

I didn't test the cable but I'm thinking that the copper outer wire might be touching the aluminium inner wire would this make a difference?

I would need to extend the earth wire to actually make a non ali ground I will try that as earth to ali roof is not ideal!

I still would of thought the SWR meter would have at least wobbled.

[timbott]

but I'm thinking that the copper outer wire might be touching the aluminium inner wire would this make a difference?

A massive difference - like 100% difference:eek:


I still would of thought the SWR meter would have at least wobbled.

Me too.

cheers, Tim

[MattHaworth]

Oh - Looks like i'll need to rewire it then :( and then get a proper earth.

Guess I need to do this before I can find out if my SWR meter has had it.

[Rex Hunt]

Do you REALLY mean a 3 inch antenna?
That will give you an enormous swr problem!
Use a multimeter set on ohms (that funny horseshoe thing) put one end on the middle of the mounting for the aerial. The other on the centre pin of the plug that goes into the CB............reading should be VERY low.
Now connect the lead from the mounting point to the outer of the plug.the reading should now be VERY high.( You will need to move the meter setting to check this!)

If the reading is still low....then you have a short circuit between coaxial aerial cable inner and outer.

It would also be a good idea to see if you can get a low reading from the Ali to chassis. You may not need to fit an additional earth on your hard top.

The SWR meter will not give you a reading if the output of the CB has been damaged by operating into a faulty aerial/feed.

Hope this helps

Let us know how you get on!


Rex

[timbott]

Do you REALLY mean a 3 inch antenna?

I presume he means 3 foot with a loading coil:)

cheers, Tim

[bob86]

Bit of a hijack, sorry.
Is it ok to have a swr meter fitted all the time?

[grantc]

Bit of a hijack, sorry.
Is it ok to have a swr meter fitted all the time?
Yup

[Rex Hunt]

Bit of a hijack, sorry.
Is it ok to have a swr meter fitted all the time?



You will get a slight loss of signal in and out......but minimal.

If it gives peace of mind....do it!

I always run one in line when using 100 Watts (Amateur frequencies I hasten to add!) so I can keep an eye on things!

Usually for CB I would say.....use one when setting up.
Take it out when you are happy that all is well.

Next time you transmit....look at the meter on the radio (signal strenth) and note where the needle goes up to.

In future a quick glance at the meter when transmitting should let you know (within a little) if things have changed from the 'normal'.

Rex

[bob86]

Blimey that was quick. Cheers

[MattHaworth]

Do you REALLY mean a 3 inch antenna?
That will give you an enormous swr problem!
Use a multimeter set on ohms (that funny horseshoe thing) put one end on the middle of the mounting for the aerial. The other on the centre pin of the plug that goes into the CB............reading should be VERY low.
Now connect the lead from the mounting point to the outer of the plug.the reading should now be VERY high.( You will need to move the meter setting to check this!)

If the reading is still low....then you have a short circuit between coaxial aerial cable inner and outer.

It would also be a good idea to see if you can get a low reading from the Ali to chassis. You may not need to fit an additional earth on your hard top.

The SWR meter will not give you a reading if the output of the CB has been damaged by operating into a faulty aerial/feed.

Hope this helps

Let us know how you get on!


Rex

Thanks Rex for this, I will give it a shot.

The CB does work although not as well as it should, Tested it out at a winch course on Saturday where a couple of the guys had CB's.

:D Definately 3 foot always get the ' & " confused.

Thanks

Matt