I'm having this problem with a 2' K40 antenna. It's caused by the lousy coax I picked up at a CB shop: The coax is so poorly shielded that it's radiating, effectively making my antenna longer. I removed the K40 tuning stub completely and have 1.2:1 SWR. Good coax should have somewhere around 90% shielding. If it looks more like 10-20%, replace the cable and retune the antenna.

BTW: Just because you have good SWR with poor quality cable doesn't mean you'll have a good signal. Radiating a significant portion of your puny power inside of your metal Jeep is not the best way to get someone to hear you (and vice versa). You definitely want your antenna to do the radiating, and not the coax.

 

I run 97% sheilded cable made by Astatic and a 4' Firestik II antenna. My readings are so high, It must be a short somewhere. This isn't a matter of "tuning" an antenna, someting BIG is wrong.
Can a radio short out and cause super high SWR readings?

 

How high is high? Anyway, if there were a problem in the radio, then the amount of power coming out of the radio should be reduced. But, once that reduced power makes it to a good antenna system, then it should radiate into the ether with minimal reflected power. High reflected power is an indication that the problem is on the other side of the SWR meter from the radio. There's another thread here where someone discovered that their SWR meter was actually wired backwards--the calibrate and SWR read positions on their switch were physically reversed. Is it possible that you picked up one of these? Also, is there someone around you who might be able to loan you another SWR meter or, better yet, something like an MFJ-259 SWR analyzer? That thing is the cat's meow for troubleshooting antenna and cabling problems ...

hxxp://www.mfjenterprises.com/Product.php?productid=MFJ-259B

 

I'm on my second SWR meter. First, I had an Astatic meter, then when I thought perhaps it was faulty, I contacted Walcott CB on line and they recommended the Vanco SWR meter (pictured here).
My readings are always in the red between 6-10. I litteraly peg the meter
I've performed all the tests, swapped out antenna's, coax, mounts and radios. This is killing me because it's really a simple thing, but for what ever reason, the answer alludes me. All I can hope for is that the new radio I ordered changes everything. Worst case, nothing changes and Im back to square one. I live in Maine and am so anoyed by this I'm about ready to drive to Arizona to have Firestik tune it!!!! (I wish, boy the warm sun would feel good right about now).

 

I read that you have already replaced your cable; but for future reference, try going to rightchannelradios.com. I picked up the following products from them:

1) Firestik K-4 stud mount

2) MU-8R18 FireRing with FME connector cable

The cable has an adapter-end on the radio end of the cable that allows you to unscrew the antenna barrel connector to facilitate install through small holes. Once you become a customer of this vendor; you will be sent access to their "Install and Troubleshooting" pages. Good help there!

I just finished my Cobra 75 with 4' Firestick install and had my neighbor help me with the antenna tune up. The antenna is mounted to the tire swing (mine hinges on driver side) on my rear bumper; and the cable run forward on the left side of my 4door. It then crosses to the center console under the driver's seat. The connector box is mounted to the floor pan hump under the carpet, just behind the right side of the dash center section. I mounted the radio/mic to the right side of the dash center projection adjacent to the grab handle above the glove box. I made sure I had a good ground where I attached the box; figuring I want good ground at both ends of the cable. I'll post pics later.

The interesting thing about this antenna tune is; that with my setup the "virtual ground plane" apparently creates a biased direction to my transmit and receive; such that my best reception and strongest transmit signal are both directed towards the front of the jeep. This is OK if I'm in a caravan (my main reason for the CB); but if I'm out alone and trying to get hold of someone; I'll have to drive in circles while sending my hailing signal.

I'm going to add a flexible ground strap from the frame to the tire carrier swing; because I don't think the ground connection through the hinge bearings will remain constant.

Anyway, check the site; and I hope you get it figured out soon.

BK

 

What should I set my meeter at? I never know what value I should use on the meeter. I'll check again, but I believe I've always got a "0" when I check center pin to center pin. That made since to me since the center pin is an isolated wire acting like a jumper between my test leads right?

As for the tip on using the screw together cable, my last cable was of that type. It had the short. I beleive the part that screwed on was over torqued and caused a short between the inner pin and the outer wire. Thanks for the tip on rightchannelradio!

 

The correct reading (when disconnected) should be close to zero ohms from center-to-center and from shield-to-shield, and infinite from center-to-shield. The 50-ohms that CB RF cable is rated at is characteristic impedance, which isn't the same thing as DC resistance. It uses the same term because sometimes it is the same measurement, but in this case we are actually referring to what a radio frequency signal "sees", which is different from what DC sees (and the ohmmeter is DC of course). If you're interested, here's a somewhat technical discussion of characteristic impedance:

hxxp://www.answers.com/topic/characteristic-impedance

 

Well, I guess we'll wait to see what your new radio does. BTW: I was born in Brunswick. Then moved to San Diego in 1950. Grew up there before entering USAF for a long career and now I'm here in the middle of the country.

 

JK Jedi, to bad they closed down the Brunswick Air Base, you could have come back home! Middle America is beautiful country. I did some exploring on my motorcycle a while back and fell in love with the America people on the coast no little about. It's funny how much I learned on that trip. Not everyone in America is as liberal as they are here on the east coast. I didn't know there were many conservatives left. Im NOT trying to turn this into a political post, just stating what I saw
I'll let you all know what the new radio does to change things. I'm afraid it won't do a thing

 

YES! I recieved my new Cobra radio and a new stud from Firestik today, tested it and all is now well! Finally, my SWR readings are out of the red zone! My old Wilson mount wasn't making connection with the antenna even though the antenna was screwed firmly in place. My high SWR readings were because my "antenna" esentially didn't exist. All I had was coax and a mount. No wonder!
Thanks for all the help everyone