a "good"swr and ground planes dont really have anything related to each other..swr is just a reading of impedence mismatch..a 50ohm resistor across the cb output will give a 1:1 match,but you try and "get out" with it!!

to maximise your setup,one should really use a field strength meter, adjust the antenna length,play with antenna mount positions for max strength indicated on meter "x" meters from vehicle,once achived then make a matching network to lower swr to an exceptable level..a swr of 3+ aint a problem,infact is quite common on a good working antenna..

but then again its just a cb..so adjust for lowest swr..
 
zen said:
a "good"swr and ground planes dont really have anything related to each other..swr is just a reading of impedence mismatch..a 50ohm resistor across the cb output will give a 1:1 match,but you try and "get out" with it!!

to maximise your setup,one should really use a field strength meter, adjust the antenna length,play with antenna mount positions for max strength indicated on meter "x" meters from vehicle,once achived then make a matching network to lower swr to an exceptable level..a swr of 3+ aint a problem,infact is quite common on a good working antenna..

but then again its just a cb..so adjust for lowest swr..
Click to expand...

I appreciate the effort but this tells me absolutely nothing :doh::rolleyes:
 
oh well....(but swr dont mean jack...it dont mean your antenna is working well or poorly,just (if 1:1) thats its matched to the rig...(as indeed a 50r resistor would be))

.by the way had a little tiny 50mw 2 channel cb "toy" in 76...spoke to a yankie trucker on it!!!fell offf my pushbike i did....!!!cost m e feckin fortune that did!!never looked back..got a 23 channel am rig...then a.. wait for it 40 ch!!!am ..then...worked out how to expand and add fm to it...(main reason being copper across the road (friend with his son,same class at school..was only 13 at time) told me he could hear me on his hoover ,tv..radio..opps..

bloody brilliant till it went legal...had a ham lience at 14..though none of the stuck up gits would talk to me...still thats proberly me now...
 
Last edited:
My aerial years ago was a DV27 (i think) mounted on an unfolded washing machine skin in the loft. Worked very well but the swr reading wasn't very good.
 
I'm glad you posted that. I was trying to remember the name of that aerial :D it had a sliding swr bit at the top... It was prolly the most popular biscuit tin mounted antenna of the 1980's - they were ****e weren't they:p
 
back in the day :rolleyes::p I mounted my 1/4 wave stainless whip in middle of sunvisor (external) on my 90 on ssb could talk to Pensylvania , and other parts of states no probs also italy and norway but you had to keep moving with the old (pre legal sets) Cobra 148 IIRC , bought it from a guy who imported race car parts ! When they brought inlegal standard was a waste of time ( so often ) . If you put the pins of a 5foot fluoro tube in the base spring it would light right up when you keyed the mike!
 
Whilst we are on the subject of CB's, I have been given a midland CB which I have set up in my 90. It has UK and Euro frequencies which are changed by pushing a little button in. Does anyone know which way is which?? It has a light which changes from green/red when the button is pushed but does not really tell you whether you are on the UK or Euro?? Have no instruction book with it.
 
Adam1979 said:
Whilst we are on the subject of CB's, I have been given a midland CB which I have set up in my 90. It has UK and Euro frequencies which are changed by pushing a little button in. Does anyone know which way is which?? It has a light which changes from green/red when the button is pushed but does not really tell you whether you are on the UK or Euro?? Have no instruction book with it.
Click to expand...

Google the model number and you'll find out in no time ;)
 
Or you could just buy a CB, buy one of those whip antenna, mount it on the wing, connect an earth from the antenna mount to the bulkhead earth point and use the damn thing.

I get plenty of range on mine for green lanes etc. Without worrying about fine tuning of antenna etc!! Lets face it, you are not going to sit on the drive and try and get Poland on it.....
 
blue beasty said:
I'm not saying it is just about body work and comments alone the lines of bung it on and forget about it are great coming from someone who really understands the tech......but if you dont and your swr is crap what do you do?

Mine was 3.5 :eek: I ran a separate earth from the base of the aerial and its now 3.....whats next....aerial trimming?
Click to expand...


Depends whether or not it's higher or lower from channel 1 to 40

Take three readings channel 1, 20 and 40

SWR higher at channel 1 than channel 40 means your aerial needs to be longer.
SWR higher at channel 40 than channel 1 means your aerial needs to be shorter.


If you got high readings right across the lot check for a short circiut from whip to ground plane, also check coax and plugs.



zen said:
a "good"swr and ground planes dont really have anything related to each other..swr is just a reading of impedence mismatch..a 50ohm resistor across the cb output will give a 1:1 match,but you try and "get out" with it!!

to maximise your setup,one should really use a field strength meter, adjust the antenna length,play with antenna mount positions for max strength indicated on meter "x" meters from vehicle,once achived then make a matching network to lower swr to an exceptable level..a swr of 3+ aint a problem,infact is quite common on a good working antenna..

but then again its just a cb..so adjust for lowest swr..
Click to expand...

The high mismatch in impedence will affect the output transistors in the form of heat..... Which is why manufacturers will recomend you do not use a CB aerial set up with a high SWR ;) But your right about the field strength meter but all that does it tell you which position your aerial works best it will not tell you your SWR is high. Also unless you have a near as perfect SWR you will not attain maximum field strength in any case.
If your SWR is high and you cannot adjust it enough to get lower than 1:2.5 at best, tells you the aerial may need to be in a different position, or it's shorted. Simples :rolleyes:

zen said:
by the way had a little tiny 50mw 2 channel cb "toy" in 76...spoke to a yankie trucker on it!!!fell offf my pushbike i did.
Click to expand...

Used to pretend we were from all over the place to wind up the gullible......sorry :eek: :D :D :D
 
Adam1979 said:
Whilst we are on the subject of CB's, I have been given a midland CB which I have set up in my 90. It has UK and Euro frequencies which are changed by pushing a little button in. Does anyone know which way is which?? It has a light which changes from green/red when the button is pushed but does not really tell you whether you are on the UK or Euro?? Have no instruction book with it.
Click to expand...


Google for the name and model number and add "manual" to the search term.. You can usually download the instruction manuals.
 
You must log in or register to reply here.

Similar threads

MonkeyLander
A 3D print out for the CB radio.
Replies
1
Views
611
Freddie17
Freddie17
1976 Land Rover
Series 3 109 Rear air shocks.
Replies
10
Views
890
1976 Land Rover
1976 Land Rover
M
Discovery 1 Body Mount ID
Replies
10
Views
602
resto_d1
R
R
2nd row 200tdi seat query
Replies
12
Views
1K
dag019
dag019
Lej
LT230 + ratios
Replies
19
Views
2K
tottot
tottot