Swr off the meter. Please help

[Truckerguy]

Swr off the meter. Please help.

Hello, I have an international semi. My single antenna is on my driverside mirror bracket. I have bran new coaxial that is not coiled up. I have tried my cobra 29 and my dads connex 3300. Both have the same result. I have searched and searched. I don't know what's causing the high swr. I am using a external meter

Thanks for any help.

 

[9C1Driver]

You must make sure your antenna is properly grounded, semi trucks with all this fiberglass now are a pain in the rear to get right. You will have to make sure the antenna system is right before you try running any radio. These new mosfet powered radio don't like high SWR levels and you can blow the finals in no time at all. I would also suggest you use an external SWR meter or an antenna analyzer.

 

[W5LZ]

Have you tried to tune your antenna yet?
- 'Doc

 

[Truckerguy]

I don't know how to tune it if I can't read the swr. My needle on the meter goes to the stopping point. Please if there is something I can try please let me know what it is.

 

[Brake Weight]

Just happen all the sudden? And/or any changes prior too?

 

[roadrage]

I don't know how to tune it if I can't read the swr. My needle on the meter goes to the stopping point. Please if there is something I can try please let me know what it is.

What kind of antenna? If you have a mirror mount, is the non conductive washer installed? If you are off the scale, I am guessing you have a short.

 

[Truckerguy]

No never been good on this truck. I was going by the meter on the cobra but just bought a external meter today. I have checked the ground to the mount with my multimeter, it's fine. Never had this problem on my pickup or other big trucks I have driven.

 

[Truckerguy]

Yes the white plastic washer is the first thing on the top of the mount. Umm antenna I have/tried... Wilson trucker 2000, firestick 3ft, and the stock international fiberglass one which is 4 or 5ft. All 3 same result.

 

[Captain Kilowatt]

I merged these two threads since there were replies in each and then cleaned up the dupes. For future reference please just start one thread on a given subject. If it is in the wrong section an admin will move it.

 

[22racer]

Is it a factory integral mirror or cab mount? vs. an aftermarket antenna mount purchased at a truck stop or cb shop? If its one of those factory integral mounts I would ditch it and set up my own mount that I know is grounded properly.

 

[roadrage]

Detach your coax from the mirror mount and from the radio. Take the multi meter and set to Ohms. Place one probe on the center conductor of the coax, and the other probe to the outer portion of the PL259 connector. If you have any reading, then your coaxial cable is your problem.
If not, before hooking up your cable, take one probe at the base of the antenna (metal portion where you place the wrench when mounting) and the other to the mirror mount. If you have a reading then the radiator is shorted to ground.
If that neither one of those, then go to the back of the radio. Place the probe into the female portion of the SO239 antenna connector and the other on the chassis or outer (threaded) portion of the 239 connector. If there is a reading, than there is a short inside the radio.

Just some ideas to check. Typically when SWR reads off the scale there is a short to ground somewhere. You didn't say the truck was new to you, you did say your coaxial cable was new. Were there problems before the new coaxial cable was installed? Did you solder or crimp the PL259s on yourself, was it done for you by a friend or CB shop, or was it from the factory? It is possible that when they were being installed that part of the coaxial shielding shorted to the center conductor.

 

[midnight special]

not wanting to hurt no one,, but has happened to me before,,, do you know how to use the swr meter,,, i had one guy once thought all you had to do was hook meter up and adjust the dial down and the swr was set,,, and i had a guy cut his wilson 5000 so short he had to get a new stinger because he didnt know he had to adjust for forward before checking reverse on test meter,,, that is why i use a mfj 259 hook up without using radio set freq,,, and look at meters gives a lot more info than a test meter,, 73s midnight special

 

[roadrage]

not wanting to hurt no one,, but has happened to me before,,, do you know how to use the swr meter,,, i had one guy once thought all you had to do was hook meter up and adjust the dial down and the swr was set,,

Haha, at least I know I'm not the only one. Years ago, when I got my first radio I read about SWR and I thought the "SWR" knob on the radio adjusted it. So I turned it down until the meter showed that it was low. I thought I had really learned something too because before then, I thought you just hooked up the antenna and started transmitting. I thought I was "the man" with all my knowledge. Its funny because I've learned so much and the more I learn, the more I realize how much I don't know.

 

[loosecannon]

please describe exactly how your mirror mount is grounded to the body of the truck.

what kind of wire/ braid?

how long?

attached to where on both ends?

is this vehicle a positive ground system?


and yes, do you know how to properly use an SWR meter?
LC

 

[W5LZ]

What all this amounts to is having some knowledge of what you are trying to do, and how to use the equipment you have. That means RTFM, Read The FURNISHED Manual, or if no manual, ask how to do it. Nothing about 'radio' is 'plug-n-play', it requires some knowledge. Getting that knowledge isn't difficult at all, but it does require some work. You've made a very good decision, you've asked what the @#$$ you're doing wrong. Now you get to do that 'work' part and find out.
Most SWR meters have to be adjusted to give a meaningful reading. When you find out how to do that, then you get to find out how that 'reading' can be interpreted, what the #3\\ it means. When you've got that idea solidly impacted between your ears you can figure out how to make adjustments to your antenna to lower that SWR, which means matching impedances with the feed line and radio.
{This is where you start wondering why the #3\\ you even thought radio would be a nice thing to do, right?}
It 'do' get worse, but it ain't no 'biggy', sort of. And it's better/easier than trying to learn to knit socks!
[Aside: learn to knit dental floss thongs! You wouldn't believe the market for those things, male/female!]
After you go thought all these posts and weed out the 'poo-poo' you will take up knitting, it's profitable!
- 'Doc

(My only excuse is that it's very early, I ain't had no coffee yet, and if you can't laugh at it you really got problems. Unfortunately, when you boil all this **i* down, it's mostly true. Oh well...)