just got a new cb and antennas. now i need a little help...

[bitchin85]

well as the title says, i just picked up two 4 foot fiberglass whips which are bolted to the back of my toolbox on each side of the truck, and my cb is an old cobra 138xlr. i picked that up for 20 bucks with a coax wire and a mic that has a battery in it (idk why?) and a volume nob right on the mic.

i hooked it up in my truck and it is real fuzzy and i can barely hear people talking when im right bby the highway. im pretty sure its because i dont have the knobs set right. i have no clue where half of them are suposed to be.

from left to right it has a dynamike, volume, squelch, rf gain, am/usb/lsb, and voice lock. on the top there is a nb/anl/off switch, a switch for the cb and pa, tone and dimmer.

can someone help me out and give me an idea of how these should be set, and how to tweak them to make it come in better..

also, does anyone know any tricks or mods that can be easily done on these? thanks

any other suggestions are welcome

[allengator]

first of all... make sure what the whips are connected to is gounded.

Next make sure the coax cable is in good shape... no "shade tree" splices!

Usually the RF gain to max.... volume about 50%.... turn the SQUELCH to the left until you hear static... then back it off a little until static is clear.


Been too long since I've CB'd to remember the other settings... should be able to find a manual online by googling the model #....

ALSO... really need to set the SWR (standing wave ratio) to transmit well... this is dont by adjusting the antennas with a meter.

[allengator]

Here ya' go!

http://www.cbtricks.com/radios/cobra...om_pg01_18.pdf

second half

http://www.cbtricks.com/radios/cobra...om_pg19_37.pdf

[bitchin85]

thanks allen. the coax is only like 3 feet long. i heard i need one that 1s 18 feet and to lay it behind my back seat.. is this correct? and how do i go about grounding the antennas? i just bolted them to my box..

[Restrorob]

Best thing you could do is locate a local CB shop, They will have a SWR meter and knowledge to set up your system to operate at it's peak level.

Improperly/poorly grounded antennas and way off SWR's can cause radio damage. The best way to ground a antenna is to run a separate ground to the vehicle frame.

Also some food for thought, Co-phased (twin) antennas are good for interstate driving but not so good for in-town use since they have higher signal strength in-line of the vehicle (out the front and back) with less strength from the sides of the vehicle. A single antenna is best for all around use in town and works alright out on the highway.

If you want the Co-phased (twin) look but want the best all around reception mount both but use only one being the driver's side in most all cases.

I've never heard of this 18ft coax before, I've got 7 mobiles and one base I've ran with different amps and antenna configurations over the years but I have my SWR meter to set them up. Never recall having to run X feet of coax and coil it up.

Disclaimer


I reserve the right to be wrong since I haven't played with my CB's in 30 yrs....



.

[Benelli]

I just run one of my two antennas, it's a lot better for what I use it for (mostly harvest, bustin' cops, talkin with friends)

Them two articles sum it up, if the toolbox is bolted to the bed then it should be grounded. That's what I was told.

[bitchin85]

thanks guys. i played with it a little today.. called for a few radio checks and i was picking up guys from the highway pretty clear and they sed i sounded good.. and i like about 5 miles from the highway. ill probly try what you say about unhooking one antenna, and as for the ground, the antenna is hooked to the mount hookes to the box bolted to the bed.. is that good enough? i asked around and theres a guy in town that will ''peak and tune'' my cb for 30 bucks. ill have him check it out as soon as i can

[Benelli]

Yeah I've always thought that's good enough a good ground is a good ground. 30 bucks is a fair price, let me know how far you can reach when you get it tuned.

[bitchin85]

yea ill be sure to get an update affter i get her tuned. and if somethings not hooked up right i figure the guy at the cb shop can tell me what to do..

[bitchin85]

well today i unhooked one of my antennas and wired the cb into the fusebox instead of the crappy cig. lighter plug i had and it sounds alot better already. i went to the cb place but he moved or closed down and didnt answer his new number... so ill have to find another place to tweak mine. and as far as the battery in the mic, should i be able to hear myself talk through the cb with that? is that why there is a battery in the mic? because i cant hear myself but others say they hear me pretty clear

[allengator]

Sorry! I didnt get updates to your thread!

No, you should NOT hear yourself when you key the mic!
the battery in the mic is just to power that particular style of microphone... not all have that feature.

You do NOT need 18 feet of antenna wire... in fact the coax should be as short as practical. (ant wire= power loss!)

Sounds like you are well on your way.
Also... the speakers in CB's usually suck... they are about 3 inch speakers and point straight down!
There is an "ext spkr" jack in the back... most truck stops sell little remote speaker you can mount somewhere so they face you... this can make a BIG difference !

If you really enjoy the CB thing, but get tired of the limited range, consider getting a technician class HAM license! You no longer have to learn Morse Code to get one!

[bitchin85]

can i just buy a name brand 3 inch sreaker and put itin the place of the original or is the external the best way to go? and why is it that i can hear my motor through the speakers? ican hear the higher/lowering of the rpms... and it is annoying..

[allengator]

No, an external speaker is much better because you can point it at your head! Huge difference!

You are hearing engine noise because the power coming to the CB is "dirty"...
They sell filters but they don't work very well!
BUT if you run power and ground (BOTH) all the way from the battery to the CB it usually gets rid of it!
Posted via Mobile Device

[allengator]

If running those wires sounds like huge pain... Try a better ground first!
Posted via Mobile Device

[bitchin85]

hmm ill have to try that. right now i have the posative coming from the fusebox and its grounded to the floor

[crazy-101]

The battery in your mic maybe for callback or echo. never used either so i have no idea. but if you hear yourself through the CB then i think your RF is to high? cant remember been a long time since i had that problem in my '68.

Not sure what year of truck you are putting one in but my ground cable in my '68 is on my dash (all metal), and the power is hooked to the ignition/radio power. Now on my '95 witch is used every day, and usually gets 300 miles a week put on it, I just have a basic AUX plug for the CB witch u can also get a most if not all truck stops. I had wire running from the batter to the CB in my '95 at first but it looked horrible and it was not practical for how much i use it.


In my '95 I have a newer Cobra 29rx Army Edition. Dual 3.5' fiberglass antennas mounted on my toolbox.
My '68 is getting a newer Cobra when i get back working and it also has dual 3.5' fiberglass antennas but they are mounted on the mirrors just like my grandpa had them back in the 70's when he owned the truck. Keeping it old school .

[retodd7711]

You are hearing yourself through the speaker because of the "talkback" option.
This is done as a modification to the radio so you can hear what your outbound signal sounds like, and can address any problems.
Such as poor grounding, squeal, or feedback.
The battery in your mic is for a power microphone.
Throw it away and buy yourself a road king 56 or an astatic brand microphone.
X2 on the external speaker, it will make a huge difference in the clarity of incoming signals.
And yes the 18 foot coax length is correct for the standing wave ratio.
Just be sure not to coil the wire, as this will create a "RF choke" which will decrease your signal strength.
Just place it loose and random behind your seat.
And remember-improper ground can be the problem.
Ground that thing to the battery ground point.
You're in Lambertville MI ?
There are truck stops up I-75 and us 23 that have c.b. shops and can get you going.
BTW_ I went to grades k-4 in Ida MI. Small world!

[bitchin85]

Originally Posted by retodd7711

And yes the 18 foot coax length is correct for the standing wave ratio.

Originally Posted by allengator

You do NOT need 18 feet of antenna wire... in fact the coax should be as short as practical. (ant wire= power loss!)

ok so im going today to look at a new mic and external speaker. so which is correct about the coax? i dont want to start a fued here, just make my radio sound the best lol. im also going to run the wires all the way off the battery to see if that helps

and retodd, it is a small world. im in ida all the time eating at carls hideaway.. its a great town

[Benelli]

I think that the shorter would make more sense.

[retodd7711]

If you search "coax length 18" You will find a huge ongoing argument about the correct length. Be it the 1/4 wavelength versus signal loss.
I'm not gonna chime in other than to say 18 feet has always worked for me.
But, your mileage may vary as they say.
I've had a c.b. in my semi for millions of miles and while it is a great way to get info on road conditions or accidents and construction.
There is also a large amount of b.s. that goes along with an open communication channel.
I've had 500 mile conversations with some great people and I've also heard some things that made my ears hurt.
With that being said, enjoy it. have fun seeing how far you can get out.
Play with some changes and see what you like.