Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 16, 2025 ...

Need some CB help

January 08, 2018, 08:06:08 pm

CB in my 1995 U300 has never worked well since I bought the coach in 2008.  Have tried to use it recently and much noise but little else. Unit was the typical Cobra handheld HH-70 with the antenna mounted on the drivers side above the side window. Have read all the postings on CB in this forum and still don't have a clear picture as to what is going on.  Have ordered a new Cobra handheld, 75 WX ST, new Hustler RVM mount and Firestick medium duty spring ( Firestick II is 28" long ).  I have found one major problem in the existing installation where corrosion between the Hustler RVM ball mount and the antenna center lead screw ( holds the "coach half" of the ball mount to the coach ) was eliminating any continuity from the radio coax to the antenna. I was able to clean the screw and screw counterbore and get a clean connection but still no joy regarding any reception or transmission ( based on the corrosion problem I wouldn't be surprised if the radio was fried ).  I've checked the installed coax ( disconnected ) from the Cobra firewall mounted junction box ( AC 701 ) and the antenna ( also disconnected ) and found no shorts or opens in the cable. I reconnected the coax to the antenna and had continuity from the antenna to the center terminal of the PL-259 connector in the dash. Here's where I'm having trouble ! The coax wiring connections, at the antenna mount, are as follows: center conductor of the coax to the antenna screw in the center of the RVM mount and the shield of the coax is combined with a red ground wire at one of the RVM mounting screws. the other end of the coax has a PL-259 that connects with the Cobra AC 701 junction box.  If I disconnect the handheld CB and check continuity all seems well on both circuits however when I reconnect the handheld I show a short across the shield and center conductors.  The short does not exist between the antenna and the AC 701 junction box.  Can anyone confirm if the coax wiring connections, at the RVM mount are correct ??

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Re: Need some CB help

Reply #1 – January 08, 2018, 10:03:40 pm

John, you may well have let the magic smoke out of something in the radio if you tried transmitting when there was no real connection to an antenna. All new equipment will probably take care of the problem. If you want to perhaps be able to send the new radio back, you can always try connecting a know good antenna system to the existing radio and see what happens.

I'd suggest that you try to find a ham radio operator near you who has an antenna analyzer. Let that person check out what you have on the coach now. If your antenna is now working properly after your repair work you will know, and then you can try the radio. Don't try to test the radio with another radio right next to it. Have the two radios a couple hundred feet apart.

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Re: Need some CB help

Reply #2 – January 09, 2018, 05:07:26 am

The short may not be a short at CB frequencies. I recommend buying an SWR meter and checking the SWR.

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Re: Need some CB help

Reply #3 – January 09, 2018, 07:11:08 am

SWR meter is on order with the other components !  Do you see any problems with the electrical connections at the antenna ?  I'm still not sure if I've got a ground plane system or a NGP system.

Jon

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Re: Need some CB help

Reply #4 – January 09, 2018, 10:58:31 am

Jon, a lot of learning and rumors about cb or ham radio's. The most important thing about any transmitter is the antennae. If the aerial does not match the frequency being transmitted, the signal does not leave the aerial cleanly and a portion of the signal is reflected back to the radio. SWR,.. the higher the SWR the less power out and the harder it is on the final's, the power out put transistors or tubes. Never operate a radio with a poor or no aerial. It will usually take out the finals in a heartbeat.

Which is the best aerial. That argument will go on for ever. Where I come from there is a huge logging truck industry. Just about everybody uses a loaded coil antennae. Most use a mirror mount aerial, but the cab mount, connected through the roof, into the vehicle  is very popular too.  A loaded coil aerial will work very well without a ground plane, but fortunately for me my Foretravel has a metal roof. A very effective ground plane. I think the best distance you can expect from the average priced cb radio, with relatively flat ground, and a properly tuned aerial,  is about 5 miles, sometimes more and sometimes less.

I would suggest you get the radio checked out to be sure the finals are ok, then test the aerial , remember, the lower the frequency, the longer the antennae, the higher the frequency, the shorter the antennae. Most people cut  the aerial too short, solution replace the aerial. So be very careful that everything is right before you start trimming the aerial.... THIS is the voice of experience talking....

I am sure lots of people will have advice to add, I am being concise, and perhaps technically a little off, but trying to make it easier to understand.

Dave

VE7 DOD  Advanced

Choosing the Best CB Antenna | Right Channel Radios

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Re: Need some CB help

Reply #5 – January 09, 2018, 11:34:53 am

Tech-Docs Index

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Re: Need some CB help

Reply #6 – January 09, 2018, 02:05:58 pm

Stump, excellant site...

Dave

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Re: Need some CB help

Reply #7 – January 11, 2018, 08:09:12 am

Hi All,

Thanks for all the responses so far and I apologize for my continued state of confusion . My coach has a fiberglass roof which would indicate to me that this is probably a NGP antenna application.  However in reading the various posts in the forum it would appear that many installations ( mine included) were set up as a GP application via a connection at the antenna mount tying the coax shield to the chassis ground - this despite the fact that there's no exposed frame surface area on the roof.  Others have reported satisfactory performance by grounding the antenna to the aluminum support structure of the roof. The mount on my coach may not be original - I have no way of knowing and I'm confused by the references to grounding the mount as there's only one connection available with any connection to the "stick" - the coax center conductor.  None of the 3 machine screws that fasten the plastic base of the mount to the side of the coach have any electrical connection with the actual antenna. Can't find anything on the "New-Tronics''(Hustler ) website that identifies their RVM mount ( Hustler RVM Recreational Vehicle Mount ) as a NGP or GP application. Note: as installed on my coach the metal 90 degree mounting bracket was not used - the plastic base of the mount is fastened directly to the side of the coach. BTW - The Firestick site is a great reference . Here's where I am at the moment.
1. I believe , based on other forum comments, that the original installation  was done by / at Foretravel and has been incorrect ever since.
2. Based on a review of the Firestick technical help files this antenna installation should have been a NGP ( non-ground plane ) application --which it is not !  According to the current Firestick II specifications my existing antenna is meant to be used in a GP ( ground plane ) application.  I know there are members of the forum who have been successful installing a GP antenna system and getting it to work however the manufacturer recommended installation would be the NGP despite the reduced performance ( about 80 % of a GP antenna range).  My existing antenna mount was manufactured by Hustler, a model RVM side mount.  Hustler's tech service rep told me that they do not manufacture any NGP products.  Have decided that the best path forward will be to install a NGP antenna and coax & keep my fingers crossed !  Not looking forward to trying to fish the coax from the dash to the antenna location.
Thanks again to all,

Jon

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