Cobra 75 CB Radio Setup Troubleshooting - D1
 

Hey guys, I'm hoping there is a CB radio setup expert out there because I am at a loss. Here's the details... I bought my '98 Disco with an existing 24" Fire Stik 2 antenna mounted to a bracket attached to the spare tire mount, Fire Flex Coax Cable ran internally to the radio box for a Cobra 75 WX ST mounted under the passenger seat. All that was missing was the handheld Cobra 75 WX ST unit. I went to my local Fry's Electronics here in San Diego, CA and picked up a new Cobra 75 WX ST and was expecting for this to be plug and play. I unpacked the handheld from the box and plugged it right into the existing radio plug under the passenger seat. I was able to pick up signal and hear random people, but no one seemed to be able to hear me when I tried to make contact. I tried a few times over the next couple days and still had no luck. I started to educate myself on CB radio systems and I went into the Ham Radio Outlet here in San Diego, and talked to one of the guys there (this is where I found out Ham guys look down their nose at CB aka "Children's Band" guys haha!). I showed him my setup pretty briefly and the first suggestion he had for me was to move the antenna to a higher location on my rig, which made sense because the top of the antenna was about 4-5" below the top of the roof in its original location, which as I am finding out would not make for a very good grounding plane. I bought a bracket from them that would allow me to move the antenna from the spare tire mount to the top of my ladder. I made the move successfully and thought all my troubles would go away. I was far too optimistic. Same result - trouble with transmitting.

Next I decided to swap out the existing radio that was mounted below the passenger seat with the brand new one that came with the purchase from Fry's. No luck there either so I swapped back to the old radio box since it was hard mounted under the seat - if I need to, I will just swap out for the new one, but at this point I didn't see any improvement with the new one so I am thinking swapping them is more work than it is worth.

I was trying to avoid using a SWR meter, but finally realized I would go no where without one - so I picked one up from Off Road Warehouse and hooked it up and ran the tests on channels 1 and 40 - yes, my doors/hood were closed and I was parked in a clearing away from anything that could cause interference. I am getting a reading on both channels that is way over 3 (which is the danger zone that can damage the electronic components inside my handheld unit, as I understand it).

Next step I did was run a continuity test from tip to base on the antenna (checked out good), checked for chassis ground on the mounting bracket (checked out good), checked continuity throughout the length of the coax cable (checked out good) and checked chassis ground on the location that the CB radio grounding wire was attached (checked out good). The only thing I saw that I didn't like, was the pin on the end of the coax cable that would plug into the radio box was loose and would slide right off of the coax cable. I took a pair of normal crimpers and flattened out the pin on the coax cable so it is nice and snug now and still fits in the radio plug, but I'm wondering if that could be the Achilles heal of my system. I will be buying a new coax cable to test out my theory, but I wanted to check with you guys because I'm betting there is something else simple that I am overlooking. Any help would be greatly appreciated because I am heading to Mammoth on Friday aka tomorrow for a couple days and then heading to Yosemite for a couple days and I think having it on the highways with the truckers would be fun and help keep me awake on the drive.

Thanks again guys, cheers! - Jordan

UPDATE: ok so I adjusted the tuning screw on the antenna and by doing just that I was able to bring the SWR meter down to about a 2.6 on channels 1 & 40. Can anyone tell me if this is a safe reading, or will this still damage my internal components? Also, any common fixes to bring it down any further than that?

Thanks!- Jordan

After reading your posts, seems like you tested everything but the mic. The mic is typically the first thing to go bad on a cb radio system and the last to be considered. Also the old fashioned way to test cb radio systems is to make sure you have the same power on channels 40 and 1 key up the system for a minute or so and see if the tip of the antenna got hot. If it gets hot (not warm, a little warm is ok) then it needs to be dialed back down. I know it's old fashioned and kinda backwoods way of doing it, but its worked for me for 10 years of driving trucks. Hope it helps and good luck.