CB Radio or PRS

Are you sending data over CB, or are you saying that 18' cables is magic for all cable runs, no matter what frequency band?

alan

Mike Roma> That is one person's opinion Jerry and I don't know that person from a

I got confused a while ago and have no idea what is 'right' for what...

Mike

Alan wrote:

Yeah, thats the problem for sure. To work properly the ground plane, i.e. Jeep, should extend 1/4 wavelength away from the antenna base in all directions.

That would be one whacking big Jeep :>.

Even at that you need a matching system (loading coil) to bring the impedance to 50 ohms, which will compromise the bandwidth & burn off some of the signal with resitive losses. There just ain't no free lunch :(.

I've got a Lil'Wil stuck to the top of my Durango, tuned to something that isn't too indecent-, ~1.3-1@ ch. 20. Just opening one door drives it up over 2:1.

It's a small miracle that the things work at all :).

Howard.

*Snip*

From what I understand CB was the FCCs' biggest mistake Allocating the band for short range mobile communications while it's very good at skip almost makes it useless for intended purposes. The skip we pick up here in the north from the people in the south with the BIG boots makes it hard to hear buddy a couple miles away. Audioooooo Audioooooo.... sheesh Unfortunatly it was so, because of the technology of the time. FRS is much better suited for short range comms. To bad they don't make a radio with at least a decent speaker.

Howard Eisenhauer wrote:

The ones I have DO have a decent speaker, external antenna, among other things. Check em out:

FrankW wrote:

I was just reading the FAQ on

and they suggest to put it in a rope like bind and not a small ball sort of thing. I am learning lots of stuff from this thread. Man, what have I started.

Thanks for your advice, its much appreciated. TW

I was thinking about putting it on the opposite side, not next to the radio antenna. I am seeing a friend tomorrow who knows more about installing antennas then I do.

TW

Thanks for the advice. I had been away for a couple of days, but it seems like I have a lot of responses to read now. Great stuff. I have steering on the right side (I am in New Zealand).

How would mounting it on the spare tyre carrier work? That would give a good height and keep it away from almost all electronics (the nearest being the fuel pump in the gas tank).

TW

TW,

First, let me say that is exactly what I've done. My SWR isn't ideal, but it's "good enough", and not so high that I'm worried I'll damage my CB transmitter.

However, according to most sources I researched when getting my CB, the bumper is among the worst places to mount an antenna for optimal performance. The only reason so many mount theirs there is that it is an easy place to mount it, and looks aesthetically pleasing.

The reason it is said to be a bad place is that bumper does not provide a proper "Ground Plane". I don't know much about how such things work, but apparently mounting the antenna to the body (such as on the rear corner panel), or in the front where you were initially thinking of mounting it, will provide a much better, larger ground plane for the antenna, and supposedly greatly increase its effective power and range, and reduce its SWR.

That's about the extent of what I know, based on the various information I read about. So, my advice:

Mount it in the front if you like it there. That works great for my friend's rubicon. Mount it on the spare tire carrier if you want. Works great for me so far. But if you want the supposed "ideal" mount, mount it to the body in the rear corner panel area, for optimal ground plane. The biggest thing (IMO) is to get an antenna that IS easily adjustable, so you can fix the SWR regardless of where you mount it.

Good luck, Bob

I am off to install it now, its a sunny autumn day with no rain clouds in sight. I'll update later, but I am now inclined towards putting it on the spare tyre carrier.

Thanks guys for all your input. TW

I have just now opened the box and am going to install it now. Lets see how it goes. The antenna is tuneable, so if there are any problems I can try to tune it or have it tuned professionally. I don't think just tuning will cost that much (paying for installation would be expensive and I would not learn anything!).

Thanks guys. TW

Wow... here in the US, the FRS radio service is limited to 1/2 watt output. If you have 5 watt units in the same range, I'd bet they get some very good range, with excellent clarity.

Hi guys, There's another reason that the bumper's not an ideal place for an antenna. The antenna's running up, in close proximity to a parallel sheet of metal. That affects the radiation characteristics of the antenna very badly and it's mounted about as low as you could possibly get it. Although better, mounting a vertical antenna on a vertical sheet of metal isn't the ideal either. The ideal mounting for a vertical antenna's always two-fold. First, the higher the better. Second, on the largest horizontal ground plane. This means that you'd like to put it squarely in the center of a metal roof. There's many issues to consider with a Jeep like beating up the antenna on low-hanging limbs and the lack of a sheet metal roof. If you have a roof rack, you could mount it there and it'd probably be best so long as you have a good electrical ground back to the body. You could also mount it in the center of a piece of sheet metal up there which would be even better. If you just have a fiberglass top, you could bond a piece of sheet metal on top of or underneath the roof and put the antenna up there. Otherwise, the easiest and most efficient, albeit ugliest, position is in the center of the hood; with a magnetic mount perhaps. The other thing I heard mentioned was that the transmission line (coax) needed to be "X" long and coiled up. I've always wondered why CB'ers insist on the fixed length coax, coiled up. It's an impedance thing that deals with wavelengths and I won't go into the technical details or basic rules of thumb. Take a look at the following site for a little more info.

Thanks for the reply. I had a lot of noise issues. After reinstalling the damn thing about 10 times over a period of 5 days, I have now found that the best power source (with least rf interference) is the head beam power lead before it goes into the head lamp switch. I have put the negative on the firewall inside the dash. Additionally, grounded the chassis of the radio to the firewall as well (separately). Now the noise level is minimal. Although, there is still some alternator whining. I have got the filters, which I will be putting on this weekend. It seems to be working a lot better now. It was a big trial and error. On the plus side, I can now take the dashboard apart in less than five minutes!

As for antenna location, anywhere front of the driver seat caused a lot of problems. I had now placed it just above the rear left brake light. My logic was this way it was farthest from the AM/FM radio antenna. It seems to be working. I am going to put a grounding strap on the antenna mount, just waiting for it to arrive in the mail.

TW

I missed part of the thread. Are you saying that "the best power source (with least rf interference) is the head beam power lead..." has less noise than running straight to the battery?? Why are you not running the power lead directly to the battery?

TW wrote:

Well, thats what I did the first time I installed it. There was so much noise and interference that I could hardly make out anything. I then tried different sources till I found the head beam power cable. Now I have no interference from the turn signals, horn, lights, fuel pump or wiper motor. I do have very slight alternator whine, but its acceptable and will go away with the filter I am fixing tomorrow.

I know hooking up this way is not advised. But this is the only way CB has worked in my RHD export TJ. Our computer unit, battery and distribution panels etc.. are all on the left hand side (either side of the firewall). My power cable is now on the right side towards the steering column inside the cab.

I am thinking of it as another Jeep thing. TW