CB power

For a Ham rig or a commercial two way I agree, but a CB draws a lot less power than those applications and the high end audio equipment that you "hear" out on the street today. A lighter plug power source for those high draw applications would be ridiculous.

Yes, they don't need as high a gauge of wire, but they certainly don't need the interference a cigarette lighter port will introduce.

tw

That should be " 'heavy' a gauge of wire"

tw

No need for you to agree, he's right with or without your agreement! ;-)

Because the normal CB mount grounds to the metal of the body through the attachment screws as does tne normal antenna mount. To avoid ground loops it's necessary to isolate the antenna and radio mount from the car body and with some antenna types that's not possible.

At least you're consistently wrong.

No problem, high = heavy:-) Most "modern" quality CB's have excellent internal filter circuits. In the "early" days, ie; 70's, engine "noise" was the source of most interference. Resistor plugs and, as I mentioned, decent built in noise filtering make the "additional" amount of interference picked up through use of the lighter plug or auxiliary power plug hard to quantify. Having said all that, it is certainly not wrong to use a direct battery to CB connection as long as it is properly fused with sufficient wire gauge. And one other point in favor of using the lighter plug as a CB power source, if you forget to turn the CB off it won't drain your battery overnight.

There's drool on your chin, idiot.

tw

I didn't want anyone to confuse the "high" with a higher wire gauge number. While I can see the temptation to cut corners and just plug it in to the lighter socket, you're not _benefiting_ your setup's performance in any way, just being lazy. CBs are low quality transceivers and need all the help they can get. While most CB manufacturers do use simple noise filtration circuitry, it is still best to run directly to the clean power source and the was the OP's question. Why not do it right?

Not all cig. sockets turn off with the key, but even using the ones that do, in order to use the radio, you have to turn the key to accessory. It's just as simple to train yourself to turn off the radio at it's own power switch.

tw

Ya got me! "just being lazy" "It's just as simple to train yourself to turn off the radio at it's own power switch." LOL! For you and me and perhaps most Jeep drivers, but human nature dictates a lot of dead batteries. I learned my lesson the hard way. Sitting in a Navajo County cruiser with a dead battery. Had to call for a jump on my portable. I got out for lunch and left the "hard wired" radio on. :P

I am a bit late likely, was out Jeeping and camping for ten days.

There are DC booklets out there if you ask at the dealer. GM has had this booklet out for years:

You 'really' need to stay away from the electrical system of the vehicle and run two fused lines directly to the battery for the transmitter like the GM booklet states. (some GM's have a nice power tap there, Jeeps don't)

If you use any of the vehicle's electrics, the vehicle warranty is void for GM's.

For a GM system you 'must' use 10 ga. wiring minimum for these power leads in order to not void the vehicle's warranty so I use twisted 10 ga. with the built in silk string cardboard condenser on all of them. (Type SJOW or SOW was recommended to me by Ericsson who made the transmitters I was installing, so I used it and never had RF issues.)

Fusing the negative line is very important because if the vehicle loses a ground for whatever reason. it can/will pull one through the transmitter and let the magic smoke out of the transmitter big time.

The routing of the wiring needs to be on the opposite side of the vehicle from the vehicle's harness and computer and should only cross it at right angles if you 'have' to cross over other wires. It is better to route the wire out to the front and cross the front top of the rad's brace then come back to the battery rather than run across the firewall where the rest of the wires run if you have to cross from side to side. (GM makes special note of this)

If you get the wiring too close to any vehicle systems, strange things happen like the ABS module fails, digital dashes go insane and in a TJ auto, as was reported on this group a while back, the tranny can jump to neutral every time you key up.

Hope this helps,

Mike

You'd be wise to learn what you're talking about before posting.

So far you've demonstrated complete ignorance of electonics, CB radio, Jeeps and common courtesy.

Please do reply and show us your ignorance in other subjects.

You must be pushing a lot of power, or your battery was s*it. I have left my CB on for like 3 days(with the truck parked the whole time) and not had it run the battery down. They draw almost no juice on receive. As a matter of fact most of the newer fuel injected cars draw more than a CB.

-- Old Crow "Yol Bolson!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM

In this day and age of multi GHz computers the 27 MHz that CB's operate that is basically considered DC. An inline RF choke will adequately block 27MHz radiating back through the power lead. Of greater concern is blocking chassis noise from the radio. A fused lead to the battery or the power block are equivalent. Any chassis ground is as effective as a separate ground lead. Metal to metal anywhere on a jeep should be less than an ohm. As far as metal mounting the chassis, that is the safest bet. If the unit needs isolation from the chassis it will be done internally. Grounding at the antenna is determined by the antenna. If it requires then a fat pigtail as short as possible is recommended. Non-grounded antenna are less effective since they do not use the body of the vehicle as a ground plane. In the final analysis, most of this does not matter if you tune the antenna for a low SWR.

And that's EXACTLY why one isolates the antenna and CB in a Jeep to avoid ground loops. Jeeps are notorious for not having good grounds, particularly back in the days when CBs were more common. It was very difficult to get a good noise free signal in Wagoneers and Cherokees leading to the development of isolated mountings to avoid ground loops.

Grounding the antenna to the body (as most installations do) is surprisingly unsuccessful when the body grounds are rusted away.

It wasn't a CB. It was a combo police radio, scanner and control for the light bar. And yes the battery was s*it :-) We replaced it last week at the county garage. I'd like to replace the entire vehicle. ;-)

Since you are getting contradictory information, here is what I have gathered on the subject:

1. Power: Go straight to the battery.
2. Ground: The following are grounded on the typical radio: a) power ground b) antenna wire at radio (ground sheath) c) antenna wire at antenna (ground sheath)

You want to prevent ground loops as much as possible. Thus the correct answer is that whatever you're attaching your ground to on the antenna end (usually a metal antenna mount bolted to your bumper or fender) should be what you attach the ground to on the CB end. Since the antenna is generally bolted to the body (or has a low-ohm AC path to ground through the magnetic mount attached to the body), that, then, is what you should attach your CB ground to.

In short, the best ground is to attach your CB ground to one of the sheet metal screws that you use to attach your CB to the body of the Jeep. If you are not attaching the CB to the body of the Jeep, the ground should instead be attached to the body as close to the CB as possible. The goal is to provide a good ground path between the CB ground and the antenna ground for use as a ground plane without worrying about whether there is enough corrosion on the cable that grounds the body to the battery to affect its impedence and thus cause it to serve as an extension of the antenna (a.k.a. "ground loop").

Note that there are antenna setups which do not require a ground plane. These use a fixed-length cable with a specified impedence and an insulated ungrounded antenna. These generally, however, provide a poorer reception on any metal vehicle that has sufficient steel for a proper ground plane. Short of attaching a radial-element base station antenna to your Jeep (which uses the radial elements as the ground plane, but it'd make your Jeep kinda tall!), you cannot get a good ground plane with a "groundplane-free" mobile setup. My handi-talkie CB with the mini-whip does not get anywhere near as good of reception as my properly grounded Firestick antenna, even if I attach the auxiliary antenna and place it on top of my Jeep so it's as high as the Firestick on the back of my Jeep. And this is despite the fact that the actual guts of this handi-talkie are absolutely identical to the guts of my permanently-mounted CB (both are Cobra designs and utilize the exact same circuit board internally, all that differs is the surrounding packaging, one is an all-in-mike design with a power/antenna box under the dash and the other is a handi-talky with the power and antenna as part of the package). The ground plane of the Jeep thus empirically has proven to be quite a bit more effective at receiving signals than the ground-plane-less approach, and you shouldn't even think about a ground-plane-less approach for your antenna setup.

-Elron

Oh, please advise me. Here's some advice for you...read what was written before you comment on it. Anyone who says running power and ground leads from the radio directly to the battery is incorrect is a F-ing moron.

tw

Well, if you know you're cutting corners and you're OK with it, that's fine. The original question was how best to make the lead runs. I think it was DougW who posted the Priority Start gizmos. Might be a good option for you. ;) Having mobile radios as large as a 100w HF radio, I got in the habit of turning them off so they didn't attract attention.

tw

Thanks for the GM docs, Mike...here's Ford's:

Special design considerations are incorporated into all Ford vehicle electronic systems to provide immunity to radio frequency signals. To maintain compatibility with vehicle electronic systems, mobile two-way radio and telephone equipment must be installed properly by trained personnel, observing these general guidelines:

Power connections should be made directly to the battery and fused as close to the battery as possible. Avoid using cigar lighter or ?Power Point? receptacles as power sources for radio communication equipment.

Antennas for two-way radios should be mounted on the roof or the rear area of the vehicle. Care should be used in mounting antennas with magnet bases, since magnets may affect the accuracy or operation of the compass on vehicles, if so equipped.

The antenna cable should be high quality, fully shielded coaxial cable, and kept as short as practical. Avoid routing the antenna cable in parallel with vehicle wiring over long distances.

Carefully match the antenna and cable to the radio to achieve a low Standing Wave Ratio (SWR) and to avoid RF currents on the antenna cable shield.

tw

Nor did I say it was incorrect, sorry about your reading disability.

Thanks for posting and showing us an additional area of your ignorance, will you do some more please? You're pretty entertaining....