CB Tuning issue High SWR

Highpocketse5

Highpocketse5

Member
I think I've read almost every possible thread on SWR tuning issues in the last couple of day and now I turn to you for problems I can't seem to solve.

I've installed a cobra 75 wx st with a 3' fire stick antennae. When tuning the antennae I get SWR readings that are off the charts. I've checked and double checked grounding issues with the antennae mount, and checked continuity in the coax and connectors to make sure I didn't have a bad cable. I did find that I had the nylon washer on the wrong side. It's now on the bottom side of the antennae isolating it from the mount.

Any ideas???
 
Moonraker

Moonraker

New member
I'm having a real problem with the same CB. Not sure what I'm doing wrong so I'm trying a different CB to see what happens . I've done a ton of trouble shooting also. Stumped....
 
MR.Ty

MR.Ty

Token East Coast Guy
Highpocketse5 said:
With the SWR well above 3.0 tuning the tip has no effect on the readings.
Click to expand...

Are you attempting to tune in an open space such as an empty parking lot or field? How do you have your cable routed? Did you spool it at all? Edit: and what CB channels are you testing?
 
Highpocketse5

Highpocketse5

Member
MR.Ty said:
Are you attempting to tune in an open space such as an empty parking lot or field? How do you have your cable routed? Did you spool it at all?
Click to expand...

Yes I tried tuning in the garage which I know was wrong and in an open field. I used an 18' cable and it is not coiled at all.
 
MR.Ty

MR.Ty

Token East Coast Guy
To be honest I'm not sure. Being that you already did all the dummy checks I'd try connecting it directly to your battery and try again just to rule that out as well.

I take it the antenna doesn't look damaged?
 
Moonraker

Moonraker

New member
A friend told me,when he took isolator off his SWR,s went way down. That really does not make sense. That would ground it out,I thought. Maybe something to do with tailgate not being grounded well. Just reaching now🤔
 
MR.Ty

MR.Ty

Token East Coast Guy
The tail gate itself is isolated but nylon bushings and isn't a good ground. Your best bet is to run it to the frame however I ran mine to the bolt for the cargo area the downs and got a good SWR reading. As far as what your friend is talking about, what isolater?
 
Highpocketse5

Highpocketse5

Member
MR.Ty said:
To be honest I'm not sure. Being that you already did all the dummy checks I'd try connecting it directly to your battery and try again just to rule that out as well.

I take it the antenna doesn't look damaged?
Click to expand...

No the antennae looks good. I'll give it a try.
 
Highpocketse5

Highpocketse5

Member
MR.Ty said:
The tail gate itself is isolated but nylon bushings and isn't a good ground. Your best bet is to run it to the frame however I ran mine to the bolt for the cargo area the downs and got a good SWR reading. As far as what your friend is talking about, what isolater?
Click to expand...

I made sure to grind off the powder coat on the mount surfaces that contact the bolts as well as the bottom where the antennae mounting stud is.

So you have a ground going from your tailgate to where the tie down lug is?
 
MR.Ty

MR.Ty

Token East Coast Guy
Highpocketse5 said:
I made sure to grind off the powder coat on the mount surfaces that contact the bolts as well as the bottom where the antennae mounting stud is.

So you have a ground going from your tailgate to where the tie down lug is?
Click to expand...

Yes. Through the where the brake light power lines are routed. Then out by the hinge on the inside of the Jeep and to the cargo bolt. If you want I can take some pictures of it tomorrow.
 
Moonraker

Moonraker

New member
MR.Ty said:
The tail gate itself is isolated but nylon bushings and isn't a good ground. Your best bet is to run it to the frame however I ran mine to the bolt for the cargo area the downs and got a good SWR reading. As far as what your friend is talking about, what isolater?
Click to expand...

The isolator or nylon washer is what he was talking about. Good point about the tailgate not being a good ground. I was kind of thinking that might be the case..
 
WarriorJeep

WarriorJeep

New member
Highpocketse5 said:
I think I've read almost every possible thread on SWR tuning issues in the last couple of day and now I turn to you for problems I can't seem to solve.

I've installed a cobra 75 wx st with a 3' fire stick antennae. When tuning the antennae I get SWR readings that are off the charts. I've checked and double checked grounding issues with the antennae mount, and checked continuity in the coax and connectors to make sure I didn't have a bad cable. I did find that I had the nylon washer on the wrong side. It's now on the bottom side of the antennae isolating it from the mount.

Any ideas???
Click to expand...

First continuity testing won't tell you if the cable is bad, need to test resistance with an ohm meter. Ive actually had several cables that were bad testing like that. Supposed to have been 50 ohm and were much higher, and every connector adds something to that
 
WarriorJeep

WarriorJeep

New member
Also I have to ask, what are you using to check the standing wave? If your using a function of the CB itself, those meters are not reliable or intended to be very accurate. In fact according to cobra the built in swr meters on their transceivers have a ratio deviance of +/- 1.086
 
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