Guys,

I bought a "mirror mount" bracket for a CB antenna from Radio Shack today. I removed the actual mounting stud from the bracket and drilled a hole in the bottom of the stake hole at the front of the bed, and screwed the mounting stud into that hole I made instead of using it on the mount it came with. I figured, the bed is metal so making my own hole should work just the same as using it on the mount supplied with it, right? Well, to make a long story short, I couldn't even get my SWR reading to stay on the meter! It was a terrible mismatch!

So I reattached the stud to the mount, put it back in the package, and took it back to Radio Shack. Then I drove to a Flying J and bought just a mounting stud alone in a package. It was made of stainless steel and even though it's the same thing, it was designed just a tad differently. So I came home and attached IT to the hole I drilled in the bottom of my stake post hole. Then I hooked it all up and I heard the weather band come on so I knew it was working better already.

Problem is, my SWR STILL is about a 3.75! I can't get my SWR reading out of the "red zone" on my meter. The stake post hole is metal (really thick metal...it was hard to drill out). And the coax is in good shape, I inspected it before installing. I'm using a Wilson antenna that I've used before with success. So where am I going wrong? Why won't my radio and antenna match better the way it's mounted??

 

tunability is the main concern here...go to firestik.com and read up on their stuff..awesome site

 

Part of your problem is the location. With the antenna mounted at the front of your bed, right behind the cab, most of your radiated energy is being bounced off the cab and reflected back into the antenna.

You should either move the antenna back further or build an extention. The rule of thumb is that the base of the antenna should be slightly above close metal objects. Sometimes you can't do that totally, so you do the best you can. Most of the current is radiated from the center of your stick, so an inch or two low won't affect it much, but it will change your pattern.

Sometimes, if you're having trouble with mismatch, try making a few coils with your feedline at the base of the antenna. This won't help with your antenna right next to your cab, but sometimes it makes a difference. Play with it.

 

I couldn't get the SWR to come down so I had to remove it. I'm using a mag mount on the roof for a temp. fix. If anyone has any ideas on how to do a permanent mount on the bed that will work, please share. I can't think of a way to do it without drilling visible holes in my new truck.

 

WxBoy,
Help me understand. Are you saying you mounted your antenna so the base of it was actually down in the stake hole? That is the base of the antenna was below the highest level of the bed side? If so, that is probably your biggest problem. Also, the stud should have came with a small plastic washer. This washer is used to isolate the radiating part of your antenna (the top part) from the ground side. I know it sounds a bit elementary, but it was one of my first radio mistakes.

As to SWR: As crazy as it may sound, SWR isn't necessarily all it's hyped up to be. SWR is a function of 3 things, impedance of the load (antenna system), frequency, and power applied. In a perfect world, your radio has a 50 ohm output. If you couple that with a 50 ohm feedline, and a 50 ohm antenna, you will always get a 1:1 SWR. If any of these vary, you will get a higher SWR.

(The best thing performance wise in terms of your antenna would be to drill a hole in your roof and install something like an NMO mount. This isn't really condusive to resale value.)

Firestik makes a stake hole mount that gets your antenna at the level of the bed side. I would probably begin there. Next, I would use high quality RG8 coax (not the smaller RG59) because it isn't as lossy.

Whatever antenna setup you choose, you should realize that your efforts will probably never rival in performance what a properly installed fixed station can provide.

Hope this helps.
David

 

I actually saw those Firestik stake hole mounts online last night and ordered one. Hopefully it'll do the trick. Thanks for the advice. It was frustrating because I worked all day to get a hole in the bottom of that stake hole to mount this thing to, only to find it didn't work. Haha...isn't that the way things go though?