CB Antenna Website

[1986Blazerk5]

Does anybody know of a good online cb shop that dosen't charge a arm and a leg for shipping. i am looking for a Wilson 5 foot fiberglass, and mounting base as well as cables, and connectors?

Thanks

 

[steelandcanvas]

I've used Walcott Radio. Good selection and service. Didn't pay much attention to shipping fees.

http://www.walcottcb.com/index.php

 

[DaveP]

Why not just hit a truck stop and pick out what you need? no shipping.

 

[velociT]

Yep, Walcott CB.

 

[OPCOM]

If you got room at all, a full size steel (or fiberglass if you must) whip will perform much better. I use one on my pickup truck. It helps knock the dead squirrels out of the trees.

I see you got a military mount. You can put a 3-section military HF antenna there, using two long sections and a short top section, and it will give a close match for CB and look correct.

Some of this info is from PRC68.com.
RC-292 Antenna

However, his page is for the RC-292, and for this we are talking different items from different antennas that happen to fit together, and making a CB whip.

For CB, the base plus two long sections and a short one worked on my truck.

He has a table there of resonances based on a formula, showing 4 long sections and a shortie for 27.7MHz, and I can't explain that unless the base is not being accounted for, plus, that is 116 inches sans base, instead of 102-108 with base. Any of the bases adds about a FT to it. I think the table there is for the configurations of the RC-292 antenna, not for using sections for something else.

The AB-2x series of elements are overall 27" long whereas the MS-11x series are 1 meter long, otherwise they are interchangeable. These lengths include the threads, which disappear when screwed together.

MS-116, MS-117, MS-118 - 39.5" long, (36.25" assenbled) multiple MS-116's can be stacked, with the 117 tapering, and the 118 the top section.
AB-22, AB-23, AB-24 - -27" long, (20" assembled) multiple AB-22's can be stacked, with the 23 tapering, and the 24 the top section.

anyway, the details of the elements are on that site. It just happened that with two longs and a short, plus the base, it worked out to be about 106" and the SWR was OK, about 1.5:1. Anything beow 2.5:1 is OK, even 3:1 if you don't talk long. Sorry this is probably confusing.

 

[m38mike]

OPCON,
I have an MP-65 antenna base and 3 MS pieces (116,117,11. I'd like to be able to use these as a CB antenna on my M38. It sounds like what you did is use the base plus a MS-116, and a MS-117, and an AB-23 to get to a 106" whip.

Did you test this setup with a MS-118 in place of the AB-23 to see what the SWR would be?

Did you consider trimming length off the MS-118 to get to the smallest SWR possible?

Was your 1.5:1 consistent across the channels, 1-40? or was that the SWR on 20?

I'd like to be able to make a very good CB whip antenna simply by mixing the available antenna sections, and not have to cut any. You're experience with this is valuable to me to help figure it out. Thanks a bunch!

 

[donalloy1]

good stuff fellas. time to hook her up

 

[OPCOM]

I did no experiments except to use the pieces as described. It's not on the present truck, so i can not do experiments at this time.

 

[m38mike]

Well, I followed your mix of 2 long and one short antenna, on an MP-65B base, and it works fine. I got a 1.2:1 SWR reading, so I'm good to go!

One issue I'm having though that you could help with is this, the CB and all are on my Electro-Willys M38. Since it's all electric drive, when I'm moving I'm getting some interference on the radio. I routed the antenna cable away from all the high voltage cables so this would not happen, but it still comes through. My next idea is to run the antenna cable through some flexible steel conduit to try to shield it. Either that or wrap it with aluminum tape like the kind used on duct work insulation. Do you have any thoughts on either of those ideas? Or other suggestions?

 

[OPCOM]

What kind of noise?

popping/buzzing that varies with engine RPM - spark noise, Usually MV splugs and wires are shielded, maybe yours had problems there. Ignition noise is always an issue on CB. I use a noise blanker for it on a car.

whining noise? maybe the alternator or generator -- try an inline "alternator whine filter" which ought to have a choke (looks like a transformer) and a capacitor.

intermittent buzz or crackling/ -the generator regulator (non-alternator vehicles) - see above for whine.

 

[Goose2448]

I hit up the local truck stop for mounts and cable. Went to radio shack for the SS 102"s. Setup works great, and looks good(2005 Suburban with Duel Whips). I have about $210 invested in the setup, which includes a Cobra 29 WX NW BT, $210 radio I got for $153 shipped, Duel 102"s, and Mounts, and 18' Co-Phased RG-59. I still have the interference for big power lines and the engine. No big deal, just squelch it out, or get the noise canceling radio(helps a lot). Its just part of having a CB. And to note, my SWR is around 1:1-1.1:1.

 

[tennmogger]

Bet your electro-drive M-38 uses SCRs controlled by PWM speed controller. (silicon controlled rectifiers, pulse-width-modulation). That's a tough system to operate a radio around. I found that out when working offshore and trying to play ham radio on the platform while they tripped the hole. Impossible due to electrical noise, and that's on an explosion proof (heavily shielded) system.

You might try disconnecting the antenna and terminating the radio antenna port to find out if the noise is conducted (coming through power leads) or radiated (through antenna). If it's from power leads, get power directly from the battery, or from a separate 12 v battery, tightly twisting the pos and neg leads together to try to reduce noise, and don't run separate ground anywhere. Even try not grounding the radio chassis as a test. Several ferrite cores on the power leads might help. Ditto on the antenna coax. A coil of coax, maybe 10 or 12 wraps on 4" or so diameter, right behind the radio, might keep noise off the shield and out of the radio.

Solutions to noise like this are most often stumbled upon by experiment (playing around!) than by analysis.

good luck!

Bob

 

[m38mike]

I figured out that the noise I'm getting on my M38 CB is electromagnetic interference (EMI). Since the 11 inch diameter electric motor that replaced my gas engine is not shielded, it's producing a lot of EMI. What's interesting is that it's affecting the CB frequencies, but not the FRS/GMRS freq's. By putting 3 inline filters between the dedicated RG-8 shielded power cable and the radio, I got rid of all the rest of the electronic static. Those filters also dampened the EMI from the motor. If I turn the squelch up about 2/3 or 3/4, then the EMI is cancelled and I can talk. Only problem is that really limits the range of who I can hear. Without a linear on your CB radio, you would have to be within about a mile or two of me for your signal to be strong enough to get past that much squelch.

Another electric vehicle builder noticed that my electric motor is bolted directly to the steel bridge that's bolted directly to the M38 frame at the motor mounts. He said that if i used a non-conductive bridge, that I might not transmit the EMI to the vehicle frame. I'll have to think about how I could do that.

tennmogger, I have a dedicated RG-8 cable coming directly from the battery to the radio box. The cable is grounded at the box. There isn't even a fuse until you get right to the radio. The 3 inline filters are all in series directly before the radio fuse. I'm thinking that I might get another inline filter to see if that improves the performance. The filters only take about 0.1 volts off the line, so they are not reducing my voltage into the radio by very much at all. I have not tried coiling the coax like you suggested. I'll need to add more coax to do that. The one I have is too short to get more than one or two coils. Thanks for the ideas.