CB Ant on Spare bracket

[D2Lou]

I read in several threads that everyone has put their ant on their spare tire bracket. Has anyone actually tuned their antenna after that? I have tried several different ant and mounts and still could not get the SWRs below 3 1/2 or so. I tried a grounding strap as well with no luck. I am using a Wilson magnet mount on the roof for now but would like to use the one on the rack if I can get it to work well and not burn up my radio! Any help would be appreciated.

 

[jcs2179]

I installed a quick-disconnect antenna bracket on the side rail of the rear access ladder, then ran the cable very nicely (hidden) to the front radio for a professional look. It wouldn't fit on the spare tire bracket.
However, I can only hear about 30 feet in front or behind me....maybe, at best. Sometimes I can't hear shit and certainly most rigs in my convoy (in the trail) can't hear me at all. WFT? I'ts defenitely a 'reception' problem, as with the crappy magnet roof top it sounds great both ways.....over my head in electronics for sure. Dang!:ack:

 

[D2Lou]

If your reception is not good that goes both ways and is bad for your radio. A shitty radio with a tuned antenna will outperform a good radio with mods that doesn't have a properly connected antenna.

 

[DiscoJon]

when i first installed my antenna on my spare tire mount, the antenna moved as i was tightening it and it was shorting out. A simple adjustment and some black tape and not i can talk and hear for miles

 

[jcs2179]

If your reception is not good that goes both ways and is bad for your radio. A shitty radio with a tuned antenna will outperform a good radio with mods that doesn't have a properly connected antenna.

yep Lou, I'm with you....but now what? (radio = crappy from radio shack, antenna= good from specialty shop)

 

[DelxE]

Seems to me that to get the best ground plane and line-of-sight, you would want to mount it on the roof. Is sounds like you have a rack so I would think that mounting it near the front-center of the rack would be most practical. This will use the rack/roof and hood as the ground plane (not sure how well the hood would work as a ground plane though). It also won't radiate you and your passengers. Radiation concerns are especially important for higher power type HAM radios. Have not tried it yet on my disco, but this would be the first place I would.

Jim

 

[DelxE]

Also, most HAM radio shops can sell a decent analog SWR meter for about $30.00. This will help you establish how good your radio/cable/antenna match is and help determine a good location for your antenna.

Jim

 

[cognetic]

My suspicion is this is a ground issue... tell me more about how and where you grounded the mount... also, are you using a fire-ring or standard mount?

I have experimented with UHF, VHF, HF, CB antenna mounting on rear tire mount, ladder, outbacker antenna mount <kinda like half a ladder on right side>, bumpers, gutters... ground is very finicky.... I used heavy duty mesh lashing between doors with dedicated strap from there to tire mount, all hidden in door then connected on inside bolt portion of tire carrier mount. Also, routed heavy gauge coated auto power cable as similar strap to ground plate behind right rear light panel and behind the knock-out vent panel.

This was necessary to get a reasonable ground....

 

[D2Lou]

I know how to tune and how to mount. I am looking for people who have gotten a good tune on their rear door to know it is possible. I do not want to hear "my radio works good " ,I want to hear "it was tuned to an acceptable level and works good". I know nothing is going to beat a magnet mount on the roof with a good ground plane. I want a compact unit that won't hit everything and flop over occasionally. If this doesn't work I may do the rear bumber after I get an aftermarket one.

 

[D2Lou]

My suspicion is this is a ground issue... tell me more about how and where you grounded the mount... also, are you using a fire-ring or standard mount?

I have experimented with UHF, VHF, HF, CB antenna mounting on rear tire mount, ladder, outbacker antenna mount <kinda like half a ladder on right side>, bumpers, gutters... ground is very finicky.... I used heavy duty mesh lashing between doors with dedicated strap from there to tire mount, all hidden in door then connected on inside bolt portion of tire carrier mount. Also, routed heavy gauge coated auto power cable as similar strap to ground plate behind right rear light panel and behind the knock-out vent panel.

This was necessary to get a reasonable ground....

I tek screwed a 10 guage ground strap(store bought braided/tinned copper) from the door to the frame/body temporarily in frustration. All that I got was less fluctuation in the SWRs but they still remained above 3(not in my comfort level). It definitely is a ground issue.
I am using a BarJan alum angle mount with the isolator that pulls through if you tighten it too much. I have used these with good results in the past not pushing them past their limits.
What is a fire ring?

 

[fs_discoII]

I have the cobra WX 75 all in 1 CB and by grounding the box to the seat bracket on the bottom i was able to get my SWR down to 1.5 which is very good in my opinion for the disco's being mostly aluminium. I have my antenna mounted to my tire carrier. Radioshack sells the bracket, but you only really need half of it to make it work correctly

 

[cognetic]

D2Lou,

fire ring schematic here: http://www.firestik.com/Catalog/k4-8r18.htm

Roger that on the fluctuating SWR... I have this too... I temporarily took a strap from under body frame and brought into a bus junction then hooked to the auto hook-up wire coming straight from the tire carrier initially... that seemed to make things right, but I never drilled through the floor to make it pretty and didn't want something flopping out the door and over the bumper. So I left the ground strap from door to frame kind of like yours... not ideal.... waiting till warmer weather to do it in a better manner...

I was wondering about creating bond between roof, bonnet, and frame... I guess that would be the best way to do it...

fs_discoII, I have ground at my multimode transceiver main box but that is no substitute for antenna ground. Works to some extent with CB maybe, but not efficient radiation for optimum range or sensitive transceiver finals!!

 

[fs_discoII]

okay don't get all technical and crap just to sound like your better, what i mean is i have the regular antenna ground then, the box ground form the box to wherever, adn then I also drilled out the holes in the box and mounted it to seat bracket.

Gosh where is sean when I need him.. he could explain this since he has done basically the same thing

All i can say is when I was down at the texas coast not to long ago I could talk to our main base camp that was 25 miles up the beach from where our convoy was.

 

[Reed]

I know how to tune and how to mount. I am looking for people who have gotten a good tune on their rear door to know it is possible. I do not want to hear "my radio works good " ,I want to hear "it was tuned to an acceptable level and works good". I know nothing is going to beat a magnet mount on the roof with a good ground plane. I want a compact unit that won't hit everything and flop over occasionally. If this doesn't work I may do the rear bumber after I get an aftermarket one.

I'm running a Cobra 75WX (radio in the handset), with a 4-foot firestick on the spare tire carrier. Over the range of the radio the SWR is tuned between 1.3 to 1.5 to 1. This is good enough for any mobile CB installation. Recently I had a conversation with a guy about 6 miles away. Both of us were strong and clear even threough mountainous terrain.

It's been said before but a good solid RF ground is a must. Plus mounting it on the tire bracket is going to give the signal a certain directionality toward the rear, However it has not been a problem on the trail, and have been able to maintain contact from one end of a caravan to the other. Mileage will vary greatly in the mountains.

 

[Ho]

lou, which antenna did you mount? and how?

i've had a 5 footer fiberglass whip in the spare carrier. tuned it fine between 1:1 and 1.4:1 within the 40 channels.

also tuned a 40m stick to 1.5:1 on the same mount.

so, i suspect either your antenna isn't resonant in the CB frequencies, or the mount is doing something to the antenna.

 

[D2Lou]

I had a 36" and a 48" firestick w/o the tuning tip(cheaper model) and then I tried a Radio shack tunable base that was SS and 60" long. The 3" didn't get any good results at a ll and the other 2 were very equal even after tuning the SS whip. The SS one did change a little but not enough to make a difference. The 36" one only stuck over the top of the truck about 8-10 inches= not enough.
So it looks like I am going to run a quality ground strap to the bolts holding the tire rack down to the frame for my best result.

 

[nrene]

Not helpful yet, but I've got a 3' firestick mounted to the spare.. I got ok reception, but not great.

My SWR meter arrives this week, so I'll tune it in and post results... I also have a mount on my bull bar up front, so I might also try that and see if there is a SWR difference and post this weekend.

 

[Mike_Rupp]

4' Firestik tuned down to about 1:1 on channel 19. I tried a 5' antenna but could never get it as good as the 4'. The other thing I like about the 4' antenna is that I can store it under the rear seat, whereas the 5' is too long.

I keep a 2' Firestik on the mount most of the time, but if I remember correctly I was only able to tune down the swr to around 2.0 or a little higher.