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Hey there, I have a question for y'all. I have a cobra 29 cb, its stock and a fiberglass antenna on the bed. I have a chevy silverado and The mount is on the Aluminum cargo management system which is mounted to the bed behind the left corner of the cab, the antenna is 8 inches from cab and its 3 ft long. It comes about 6 inches above the cab itself. I have an swr of 3 and a little higher. It is higher on 1 but only by a little bit. I tried to run a ground wire 12gauge to a couple different points under the hood and it did nothing. Help please.
1) Ground your antenna - the cargo management system may or may not have a good ground to the body. You want to run your ground wire from the mount bracket on the antenna to a good body ground.
2) I would look for a taller antenna. 6 inches above the cab is not very much. Higher is better, closer to the center of the truck is better.
I have had good luck with the Francis antennas since I came across them 15 years or so ago.
Dave / Believer45
__________________ THANK YOU to all the heroes in our military and all the heroes at home who wait for their safe return. I am humbled by and grateful for your service and sacrifice.
'95 F250 ext cab long bed, PSD, 5 speed manual, two wheel drive, 3.55 gears, 286,000 miles, LUK clutch conversion, 450 lb homemade REAR BUMPER, homemade open element AIR FILTER, 36" tall ARE contractor cap. With tools, full of fuel and me on board (300 lbs) steer 3620, drive 3860 total 7480.
Z71..maybe others will chime in cause I'm rusty..meantime JMO...
You need longer/swr adjustable antenna..2/3 should be above cab top. You can tune fglas BUT its tricky/time consuming & require's various parts.
Move mount to good metal contact. You might need diff. type depending on where you put it..ready made or make your on. I assume coax is ok & around 18' long for starters. Good luck!
So ground from the mount to the chassis. I tried to use a 12 ga wire and ground it to a couple different bolts under the hood and nothing...what gives?
Most likely antenna location. Not high enough above the cab.
Dave / Believer45
__________________ THANK YOU to all the heroes in our military and all the heroes at home who wait for their safe return. I am humbled by and grateful for your service and sacrifice.
'95 F250 ext cab long bed, PSD, 5 speed manual, two wheel drive, 3.55 gears, 286,000 miles, LUK clutch conversion, 450 lb homemade REAR BUMPER, homemade open element AIR FILTER, 36" tall ARE contractor cap. With tools, full of fuel and me on board (300 lbs) steer 3620, drive 3860 total 7480.
Your antenna should be 2/3s above the cab as mentioned before. Thats probably the biggest problem your having. Also ground wires must be kept short as possible. Try a longer antenna. I would recommend a fire stik 2. I have had good luck tuning them to all sorts of things that should have never worked. Once tunned one to an upside down filling cabinet drawer on my friends roof. We managed to get a 1:3 SWR on it. He was not able to have a big base antenna so it worked pretty good.
__________________
-Justin
1984 F250 6.9 C6 2WD Pushbutton Wellman GPs, True Flow air filter, 7.3 IDI air cleaner Cover with no Soup bowl. VDO Vision water temp gauge, ISSPRO EV Pyro
So ya think im getting a good enough ground on the aluminium which is attached to the bed? Because when I attached a ground to misc. bolts nothing changed. I bet I need a longer antenna. Any other thoughts??
All three who have responded suggested a longer antenna or move yours so it is above the cab. I would start there.
__________________ THANK YOU to all the heroes in our military and all the heroes at home who wait for their safe return. I am humbled by and grateful for your service and sacrifice.
'95 F250 ext cab long bed, PSD, 5 speed manual, two wheel drive, 3.55 gears, 286,000 miles, LUK clutch conversion, 450 lb homemade REAR BUMPER, homemade open element AIR FILTER, 36" tall ARE contractor cap. With tools, full of fuel and me on board (300 lbs) steer 3620, drive 3860 total 7480.
In addition to the ground, you need a ground plane.... not just a cargo management system AKA Roof Rack.... the footprint of it is not large enough. Think square feet not square inches in area. An RF ground is not the same as an Electrical ground. RF does funny things and does not follow the same properties as DC or AC power. 30+ years in component level RF technology.
__________________
2008 F-450 Lariat loaded on order 7/3/07 delivered 9/13/2007 Pueblo Gold and all the goodies except Nav radio and moonroof and Fisher 8'6" X-blade
2005
F-350 Lariat LOADED CC SRW LB 6.0 SOLD
Med. Wedgewood Blue
All Options except moon roof
8'6" Fisher X-blade SS
2003 PSD 6.0 Lariat CC SB SOLD
All options but the moon roof
The metal truck body is the ground. if the base of your antenna is located below the highest point of your truck (ground) it isn't going to radiate properly. Locate the base of your antenna at the highest point of your truck. the best is to drill a hole in the roof of the cab and mount it that way.
Band..brings back old memories. I certainly agree..mount on top of roof. Best set up was my old E150 van. 5/8 Drilled/mounted top dead center of roof..great send/rec.
But, you don't need to drill thru cab roof to get good results. Current ride I use mag. mount on top/center of cab. If carrying boat, I move mag. over to side of carrier. Both ways I get very low swr's. Using adjustable one's..even both my francis give real low swr's.
2/3 of antenna above cab. is what I found worked best for me when I had mount on bed rail (behind cab) I figured out how long mount needed to be to get my 6ft francis 2/3 above cab roof. Surprising at time..got really low swr's with no adjustments. I did use string to cab (lense screw) to keep it more vertical OTR. Used with mag. on cab top (while stopped) really increased send/rec. So...
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CB Tuning Question - help!
We managed to get a 1:3 SWR on it. 
He was not able to have a big base antenna so it worked pretty good.
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