SWR problems - Cooltech tailgate mount, 4' Firestik

gwk

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I've read a gazillion threads and watched a bunch of videos on this subject, and I'm posting as a last stop before finding a cb install shop to figure it out.

Here's my setup, and the testing I've done already: I've got the Cooltech mount on the lower hinge (upper hinge won't clear my garage). Grounding and continuity tested at mount (pieces that should be able to see each other can, pieces that shouldn't can't per firering diagram). For good measure I ran a 10awg wire from the mount to under one of the cargo hooks (tested as ground referenced to battery negative terminal). Ran coax up passenger side tucked under plastic where available. Tested ground and continuity at the radio end - outside and center pin, ground reference battery negative and one of the ground bolts next to the door harness.

Radio is Uniden 510. It's powered from Aux 4 off the harness in the passenger floorboard. Negative to one of the bolts by the door harness (crimped a 1/4" eye terminal to the wire). Radio powers on fine, once I replaced the inline fuse which was open when I got it :-/

SWR is above 3 across the band. I measured it in a parking lot away from other stuff. Tried it softtop down & windows down first 'cause that's how I drive it, then windows up, then top up. I got one set of readings around 2 with the top down & windows up, but couldn't repeat it later (tried again after the top up tests.)

I'm stumped, and looking for advice. I'm about to head back out and recheck all the continuity and ground measurements, but from there I don't know what to do. Thanks in advance for any troubleshooting tips.
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gwk

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Replying to my own post in case it might help somebody else...

Rechecking all the connections I found that I hadn't tightened the connection enough between the FireRing and the mounting stud. I was afraid I'd crush the nylon insulators.

Connecting a probe to the coax center pin up front by the radio and testing against various parts of the mount, I found that there was no connection to the center pin except directly with the center of the FireRing. Previously I'd probed around the mount itself and there was connectivity between the stud (above the mount) and bolt (below the FireRing) so I thought I was good, but apparently not.

I took the ring+stud off the mount and reassembled it, tightened it up until I got continuity inside the stud, then (having confirmed that would work) put the mount back together, confirmed continuity between the stud and center coax pin, and reattached the antenna.

I had to lengthen the antenna a bit - first reading was [email protected] 40 and [email protected] 1 - but now SWR is 1.2 - 1.5 across the band.
 

Rb75

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I just installed a Cobra 75 with the Cooltech mount on my JLU Rubicon. Unfortunately after carefully going through step by step I tested it and am getting SWR readings well into the “red zone”. I was hoping your fix would help but unfortunately not. I saw a slight improvement (possibly). Was there anything special you did with the setup? How hard did you have to tighten it? Any other tips?
 
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gwk

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Was there anything special you did with the setup? How hard did you have to tighten it? Any other tips?
I had to tighten it pretty hard - enough that I was worried it'd break. As noted I ran a wire from the Cooltech mount through the tailgate and grounded it inside the Jeep, because lots of people say the tailgate itself is intermittently grounded due to variable resistance through the hinges.

Other than that all I did was go point to point checking grounds and continuity. I dug out my multimeter and bought a pair of 10' extension leads. To check ground I clipped one lead to the battery negative and measured resistance to that. That's how I confirmed ground points at the radio and at the antenna mount, and what I measured the mount and the antenna shield against.
 

bwilliam79

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I've got a Cobra 75 CB and spent some time today trying to tune my SWR. 4' Firestik with the CoolTech antenna mount on the upper bracket of the tailgate. Best SWR I can do is 2.2-2.3 on both Channel 1 and Channel 40. Everything I read says it's not great, but it won't fry anything.

I did have the doors off (it's was a nice morning) and the tuning was done in as much of an open area as I could get to. I don't have any loops in the coax, but there is probably 6" of slack i just pushed up behind the glovebox. I'm not sure what to do to further get the SWR numbers, down any further. Any thoughts on what I should try/check?
 

Drkarr

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I had no success getting my SWR down with the Cool Tech JL mount system. My SWR was 3.5 after I checked everything and reinstalled everything, not my first CB system BTW. I brought my Jeep to a CB shop run by the same gut for 40+ years. His opinion was the coax cable and mount was sub par and that was the problem. As soon as we swapped out the mount and the cable for new ones from the shop the SWR was down to 0.5.

I have been calling Cool Tech about their cable/mount and the phone has been ringing busy for a week and they have not responded to any of my emails.

In short, don't but the system, its crap. Just go to a CB shop and have them set you up.
 

broncoman2000

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Sorry to hear the trouble you guys have had with Cool Tech CB system. I bought mine last June, installed everything, and after wiring it up, within 15 minutes had great SWR, and have had 0 issues since. I just got to say that for my set up, it worked great. JLUR, upper hinge as I remove the antenna when not wheeling so height is no problem, hard top, rarely removed.
 

LoganDzwon

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I have a cool tech antenna brakes and antenna. I added a bonding strap between the tailgate and tub. My SWR on channel 19 is 1.1 and under 1.4 on 1 and 40.
 

Hayseed_JLUR

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gwk for the win...

Installing another Cobra 75. No issues in the JK. So put a second in the JL.

Could not swr down below 3 - sometimes 10. It was within 0.1-0.2 between channel 1 and 40 but was always high. Reground the unit and checked all connections.

Took apart the antennae from the mount and cranked on it like a redheaded step child and now both channels are 0.2 and 0.4 respectively. And then was in a confined space. So pretty happy and thanks gwk for your post.
 
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Bryce

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Bring this back to life.
I was having issues with High SWR with the Cooltech Kit too. I added a ground from the Cooltech Bracket to the tub. Tested the continuity from the bracket to the ground in the passenger footwell (same ground I used for the radio) and that was good. I finally replaced the Firering cable with a regular 18' RG6X cable and mount PL259 on the antenna end and FME with FME to PL259 on the transceiver end and a Firestik K-4A mount. Tested SWR before hiding the cable and all is good. Pulled out the old cable and put in the new. Went to test SWR again and it's way off. Come to find out that the FME to PL259 with the firering cable s not tightening the cable to the radio at all. I could pull the cable out without loosening the outer ring. On the new one (Wilson 305-830) I could not pull the cable off, but it was loose. I stuck a rubber washer down in the plug and it tightens up good and keeps continuity between the radio, outer paelrt of the cable and the mount now. SWR below 1.5 now.

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JPAloha

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I was able to tune my Firestik to a reasonable SWR using the Cooltech mount but as a point of note the bracket had to go on upside down (top hinge) in order to clear the 35x12.50” tires on Teraflex Alpha mount.
 

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When I checked the SWR for my ham radio install using this mount, it was 1.2 at 144 mhz and 1.8 and 148 mhz. What I found interesting was when the spare tire was off it was 1.2 and 1.5 at the ends. I put the tire back on and the SWR went up to 1.8 again on the high side... hmmm...

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nostatic

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Bring this back to life.
I was having issues with High SWR with the Cooltech Kit too. I added a ground from the Cooltech Bracket to the tub.
20190824_114246.jpg
How/where did you run the wire from the mount? I actually am getting good SWR on HF hamsticks but I can't get a Tarheel below 2:1 on 20m. I'm looking to bond the back of the mount to the tub but looking for the easiest routes. I did add some bonding underneath (exhaust and lower tub to frame). I"m thinking back of the Cooltech bolts, gettin low profile nuts and connect braid there, then connect to the stay connection as that is connected to the body.
 

Bryce

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How/where did you run the wire from the mount? I actually am getting good SWR on HF hamsticks but I can't get a Tarheel below 2:1 on 20m. I'm looking to bond the back of the mount to the tub but looking for the easiest routes. I did add some bonding underneath (exhaust and lower tub to frame). I"m thinking back of the Cooltech bolts, gettin low profile nuts and connect braid there, then connect to the stay connection as that is connected to the body.
I ran it throgh the tailgate and out the wire conduit to the body tub. Theres some nuts under there to ground it to... I cant remember exactly but it may have been where the arm the stops the gate from swinging wide open bolts to the tub.
 

nostatic

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I ran it throgh the tailgate and out the wire conduit to the body tub. Theres some nuts under there to ground it to... I cant remember exactly but it may have been where the arm the stops the gate from swinging wide open bolts to the tub.
Cool, thx, I'll pull the right side panel (I'm assuming you mean under there - that's where the stop arm goes). I ran some braid under the hold-down carpet piece but it didn't solve my issue. I can't get 20m to go below 2:1 with my TarHeel. What is odd is that I can get below 1.5:1 on every other band and a 20m ham stick tunes near flat so not clear what is up. I'm working with the Tarheel guys to try and sort it out but more/better bonding is never a bad thing...well, unless I drill into a harness or something :idea:
 
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