Another Nube!

[jdfet]

Hey guys (and gals), I remember having a cb when I was younger (1976-ish) and I remember having a call number and all! People were very polite and you had the regular folks you talked to. Now..........I cant even have it on with the kids in the truck with me!! Cant believe the foul language and the commercialism it has taken on!! Forget all of the things your not supposed to do because of fines.... you have to catch them first!
Anyway, I recently got the itch to put a cb into my truck (Ford F150, 2008) and have had some interesting things drop into my lap! I had an old Road Talker by Sears come my way for free and a Cobra all-in-one handset for $10.00. I also got a K40 antenna for free as well.
I figured this was enough to get me started and so have mounted some things but something is not correct. Oh yeah and I got an SWR meter for free as well (Midland).
Heres my set up: I have the antenna (58") mounted to the Kobalt tool box. I have a ground wire (6 guage) going from the metal base of the antenna down between the cab and bed and then wrapped around a bolt that holds the side step on. I believe this to be a good ground. ??? Do I need to ground the tool box? It rests on the bed liner and so is not grounded itself. Oh yeah, and the antenna has a custom base I made of HDPE and so it does not physically touch the tool box.... ok so grounding the box wouldnt matter....
I used the SWR meter but the needle jumps around on it alott and seems to be 'touchy' when I touch the calibration knob. Do they go bad?
Whle attempting to tune, On 19 I adjusted out to the end of the red line and then while keying the mic, I switched to REF...the neddle was around 3.... this is to high from what I read on this site. Is the K40 adjustable?
Should I sell the Cobra all in one (they go for about $100.00 used) and get something else? Im not looking to talk to everyone around the state just to get traffic and make a few freinds. Anyway, thats alott to drop for the first post. Thanks in advance for any help/advice.
-Jeff

 

[JayMojave]

Hello Jeff: Kind of difficult to give good advice as not seeing the antenna installation.

Mounting the antenna on the tool box is convient but doesn't always work well as the antenna is near the top of the cab throwing off the antenna performance some what. And it will effect the SWR.

Is this a magnet mount K40 antenna?

The tool box should have the coax shield wire connected to it, and have the tool box grounded to the trucks body. This may not change a hole lot but is worth a try.

I would think that the K40 antenna SWR should be around 2 to 1 mounted on top of the tool box. The beeter loacation is in the center of the cab on top. Or using a L bracket at the top aft brake light, to mount the antenna.

Jay in the Mojave

 

[jdfet]

The antenna is not a magnetic mount. It is on an HDPE (or plastic) base that I made for it. The antenna does not touch the metal of the tool box at all.. mounted in that location it is still very tall over the roof of the cab. It is 58" tall.
Does grounding the box really help since the antenna does not touch it? No metal part of the antenna that is.
I had the antenna on a home made magnetic mount on the roof. The SWR readings were the same. Plus it looked like a lightening rod! lol
Is the K40 adjustable??

 

[crimsonpirate78]

First off the antenna needs to touch the box it uses it as a ground plan as almost all mobiles do. its a pick up use one of the stake holes and mount it there where it is your getting a ton of reflected signal messing up you SWR. also try new coax and a new meter YES they go bad.

 

[jdfet]

So then what about the ground wire that goes from the base of the antenna to the truck frame? Is it needed? I found out how to adjust the antenna up or down if needed.

 

[robertmac]

Oh brother

Listened to the CB frequencies today and OH BROTHER. Now I know why I am glad I threw out the last CB radio I had. In one word, most frequencies I listened to was PATHETIC!

 

[LtDoc]

Separate ground wires.
If the box the antenna is mounted on is in electrical contact with the bed of the truck, and if the bed of the truck is in electrical contact with the frame of the truck, there's really no benefit to adding a separate ground wire from antenna to truck frame. The thing is already electrically connected, right? Why add more wire when it isn't going to be doing anything constructive?
And just for clarification. The antenna (depending on what type/style it is) isn't connected to the mounting point, but the braid of the feed line is. In the case of using a base matching device on an antenna, such as the K-30/K-40's do, then the coil in the bottom of the thing does make contact with the vehicle's body or "ground". It will show a short if measured with a multimeter (a DC measurement), but at radio frequencies that 'short' isn't a short at all. Big difference there.
- 'Doc

 

[jdfet]

Ok so then it sounds like the current set up is fine. I have an 'electrical' connection from the metal base of the antenna to the truck frame. No need to ground the box. I think I will start by getting a new swr meter and go from there. Is the antenna adjustment done in small increments? Like 1/8" increments? Or more like 1/2". I realize this could depend on what is need as far as an adjustment goes but didnt how touchy it would be.

 

[LtDoc]

Antenna adjustments done in small increments?
In general, that's a pretty good idea! It's also a pretty good idea to carefully watch that meter while doing that 'cutting'. Not much change with a small section of antenna 'lopped off'? Okay, using some judgement, make a slightly larger cut the next time. (Actually, a -lot- of judgement should be used since cutting off too much isn't exactly reversible.) One way of determining how much you can cut off at one time is by taking a careful look at any 'built-in' adjustment methods of the particular antenna you are adjusting. Most, which use a set screw in a ferrule to make adjustments have a small adjustment range, so take note of that 'range'. Make your cuts smaller than that and it can be nullified by just raising the whip to the 'top' of the ferrule. I'm not sure that made any sense, but do you see what I'm saying? The whole 'trick' is to not bite off more than you can chew, sort of...
- 'Doc

 

[jdfet]

i have not done any cutting of the antenna yet. Just wondering about the adjustments at the base of the antenna. I think I will start with a new swr meter.