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Message started by splash07 on 09/18/13 at 07:32:15

Title: Any CB'ers out there?
Post by splash07 on 09/18/13 at 07:32:15

I am having trouble with my CB install. Was hoping there were some CB gurus on the site. The wealth of knowledge our members have never ceases to amaze me.

I installed a small cobra radio in my car, ran power from a 10 amp fuse in the in cabin fuse box, grounded radio to firewall. Antenna is a cheap scosche from wally world with 10' of coax connected to another 4' piece of coax to make it all the way to the radio. The Antenna is a magent mount and is located on the trunk lid. I grounded the trunk lid as well to the main frame so I would get the best ground plane possible. Now I am trying to tune the radio and antenna and I have it so the SWR on ch 1 is the same as ch 40, but they are both around 2.7. What can I do to get the SWR lower. I am thinkin switching to a better antenna, amybe a lil wil will solve my problems.

Title: Re: Any CB'ers out there?
Post by Charon - FSO on 09/18/13 at 07:47:11

Try putting the magnet mount antenna on the roof and removing the 4' cable. Sometimes the cable length is figured into the antenna impedance.

Added: Check your SWR on Channel 20, mid-band. It should be lowest about there. A CB antenna isn't really a wide-band antenna. I'd suggest ch 19, except you might annoy others transmitting there. Ideally, you adjust for lowest SWR on the channel you intend to use most.

Title: Re: Any CB'ers out there?
Post by splash07 on 09/18/13 at 07:56:04

If I move it to the roof then I will need to make a longer piece of coax to connect to the 10' piece since the antenna will be even farther from the radio. Ive heard that coax should be in 3' lengths for best performance, true?

Title: Re: Any CB'ers out there?
Post by justin_o_guy2 on 09/18/13 at 15:15:22

Cheapo antenna? Ditch it,, get a decent antenna. I had a Wilson magnetic,, worked pretty good.. One piece of coax, connectors create problems,
I have a whip antenna with ( IIRC) 18' of coax. Ive seen it get WAAY out,, Im in Texas & Ivetalked to Alberta Canada once. Ive listenbed to the same guy talk to California,.& Ive had it hit locally somewhere in the range of 20 miles. I talked to the guy I gotthe Radio from & I know where he was & I know where I was & it was Waaay more than just across town,
Coaxloength matters, just having "enough" isnt the answer. SWR on the antenna is increased when the coax isnt the right length. You mite need to take the radio to a truck stop. Thereare CB shops at a lot of them. You can have it hooked up to a KNown good antenna & see what the power is & see how it measures up on SWR. It may need tuned, the mic may be crapped out,,but about $10.00 will tell it,
You can buy a decent antenna , too..
Myradio is fromthe 80's & is tuned a bit Hot,, but no amplifiers are in line,,
SWR = Standing WaveRatio.. High SWR = Signal cant jump off the antenna, You can get a meter & put it in line between your radio & antenna, or, you can have "The Guy" at the shoip do it,, prolee lookin at another 10 bux..

Title: Re: Any CB'ers out there?
Post by Steve H on 09/18/13 at 15:28:36

SWR should be low as possible. Cheapo antennae generally have problems. Very short radiators make for very narrow band tuning. Coax length will cause SWR to go up or down. Center of the roof is the best spot for overall performance. Trunk mount will have some issues with the bodywork at the same height as the radiator on the antenna and cause funky SWR issues. It has also been found that leaning slightly forward so that it straightens at speed tends to work well for mirror mount truck antennae.

As has been said, drop the bucks on a good antenna. I've got a Wilson 1000 magnet mount, SWR barely moves off of 1:1 anywhere in the band. K-40 is also a good antenna. You can expect to drop close to a bill by now for either if antenna prices have kept up with everything else. Both those antennae will handle a kilowatt with no problems. I've talked all over on mine with just the radio. Never needed any kind of amp. Make sure your connectors are good. Sharp bends in the coax can sometimes cause some issues but usually nowhere near that bad.

The SWR is the amount of power being trapped in the coax vs the amount of power getting out the antenna. At 2.7:1, you are losing 2.7 watts of output for every one watt you get out the antenna. (This is how a radio tech explained it to me) With a 4 watt radio, you aren't going to talk very far.

Title: Re: Any CB'ers out there?
Post by Midnightrider on 09/18/13 at 15:32:30

I didn't even know you could still buy CB's anymore.

Title: Re: Any CB'ers out there?
Post by clueless-FSO on 09/18/13 at 16:53:44

Not a Cb er but a Ham operator. Antenna should have a set screw on the whip to adjust the length, and the SWR. Shortening raises resonant freq. and lengthening lowers. Make sure coax is good.

Jim/AB4XO

Title: Re: Any CB'ers out there?
Post by ToesNose on 09/18/13 at 17:11:13

Man and I thought there was going to be a picture of a sweet Honda CB!!! ;D

Title: Re: Any CB'ers out there?
Post by Face on 09/18/13 at 20:38:13

2D09040E090708141209040512600 wrote:

I didn't even know you could still buy CB's anymore.

Boy, howdie, they're alive and well! I work for the local Peterbilt dealer and we sell a shiteload of 'em. They're even comin' out with new models all the time. The current bada$$ is the the Cobra 29LTD in chrome. Gaudy son of a B....but sells like hotcakes!

The only thing truckers love more than their CBs is chrome, so it's a winning combination!

Title: Re: Any CB'ers out there?
Post by splash07 on 09/19/13 at 05:50:03

OK, I am going to get a better antenna with a solid piece of 15' coax and see what that does, maybe a wilson 500 or K30 magnet mount. I will report back soon. Thanks for the info all!

Title: Re: Any CB'ers out there?
Post by runwyrlph on 09/19/13 at 07:53:33

4C475549485555260 wrote:

[quote author=2D09040E090708141209040512600 link=1379514735/0#5 date=1379543550]I didn't even know you could still buy CB's anymore.

Title: Re: Any CB'ers out there?
Post by Charon - FSO on 09/19/13 at 10:26:08

CB and cell phones supplement each other. Cell phones require that you know the number to call, while CB talks to anyone in range. Also, although like muffler laws no one pays attention, it is a violation of DOT rules for a commercial driver to use a cell while driving.

Title: Re: Any CB'ers out there?
Post by ZAR on 09/19/13 at 10:52:56

A lot of good advice here. There are lot of misconceptions about radios,amps and antennas. I'm also a ham operator and my mentor stressed constantly "you can take a $10 radio and talk around the world with a good antenna or you can take a $500 radio and talk around the block with a piece of crap antenna" So far after over 40 years of playing with radios that has always held true.

Larry
KG4ZAR

Title: Re: Any CB'ers out there?
Post by old_rider on 09/19/13 at 16:51:14

I've always had a CB either in my vehicles or capable of being put in them. Have an old 80's cobra in the truck now, that was "adjusted" internally using the external pa circuit to boost the power. Can't get anyone to answer a radio check around here so i'm not sure if i'm putting out a good signal or just white noise.

Title: Re: Any CB'ers out there?
Post by justin_o_guy2 on 09/19/13 at 19:59:13

Before you decide the coax length, talk to a CB repairman. YOu find them attruck stops often, IIRC, 18 feet is like 1/4 wave length on 19, or some part of a wave length,, just ask around first,.,
Dont coil up any extra length. If its coiled up your transmitted signal can make the loops charge up inductively & choke your power.