CB antenna ground plane

[Bill Lampkin]

Does anyone know if Beaver used a ground plane (metal plate) in '05 Patriot Thunder w/ factory CB installation? My CB antenna is working as an overhanging limb annunciator; I'd like to remount the antenna with a spring mount, but I was wondering about the ground plane.
thanks!

[Fred Brooks]

              Hi Bill,

       That is a good question, you may research what Monaco was doing on their hign end coaches. Either way, if your going to install a spring mount make sure you change the antenna mast with it. Then check the SWR with a meter to get the length correct. Regards, Fred

[Jerry Carr]

Fred maybe I should start a new thread but I have a cb question, I have the original Cobra mike style cb on board and can only transmit a few yards and the a little better on the incoming I did try a new antenna called a hot stick but that really didn't help much. Does anyone have any suggestions that may improve the signal strength   

[George H. Wall]

Have you checked your STANDING WAVE, as Fred suggested?

[Jerry Carr]

I am not sure how to check the standing wave all I have ever done with the cb is change the antenna when the old unit broke, it's never been a strong signal in or out in the 8n years we have tried to use it. 

[Bill Sprague]

Fred maybe I should start a new thread but I have a cb question, I have the original Cobra mike style cb on board and can only transmit a few yards and the a little better on the incoming I did try a new antenna called a hot stick but that really didn't help much. Does anyone have any suggestions that may improve the signal strength   

Jerry,

There was a CB shop near the SeaRay store on old 99 near where you keep your motorhome.  Several years ago he fixed mine so it worked pretty well.  We used it for coach to coach communications when traveling with other couples, but now I prefer cell phones for that.  We also used it for monitoring traffic problems by listening to the truckers whine during long backups.  Now I prefer Google Maps with traffic for that.

Try http://www.truckcitycbgps.com/

The "motorcabin" will not be getting a CB!

[Roy C Tyler]

 Jerry
If the SWR (Standing Wave Ratio) is too high, it is possible to blow the output transistors on a CB Radio.  The SWR is the reflected power when there is a mismatch between the radio and the antenna and the power is reflected back into the radio.  The way to check it is with a SWR meter and adjust the antenna length so that you get a reading as low as possible.  The instructions usually come with the meter and the meters are inexpensive.   Walmart has them for less than $17.

[Jerry Carr]

Thanks Roy I will see if I can find one today and let you know how this works, it's hard to find a CB shop today

[Phil N Barb Rodriguez]

Jerry,

To save yourself a trip back to the store when you pickup an SWR meter you will need a short piece of coax, with connectors installed, in order to connect the SWR meter between the antenna and the existing coax. The shorter the better. Short piece from the antenna to the SWR meter, existing coax to the SWR meter "in".

In the meantime, if you can get to both ends of the coax you might want to take your ohmmeter and do a continuity check between each end of the coax. You will want to do a check on the center pin of the coax with your ohmmeter leads touching each end center pin. Do the same for the ground. The ground test would be done the same way by touching the leads to the outside of each connector. If your have good continuity wiggle each connector one at a time to see if there is a short in the center pin or the ground. 

If all is good with the continuity check and you have to adjust the antenna there should be an allen screw at the base of the antenna where you can loosen the antenna and slide it up and down while checking your SWR. Someone will have to key the mike to do the check. A good SWR reading would be 1.0 to ~1.5. The lower the SWR the less power you loose. There is not much power going out of a CB radio, only 5 watts out the back.

It's probably easier to take the coach to the CB fix-it place Bill mentioned.

That's my story and I'm sticking to it.....

Phil

[Jerry Carr]

Thanks everyone I do think I will take it to the pros when I get home.

[Edward Buker]

Jerry,

Don't be too surprised if the swr ratio is not that great. Beaver may have just tied the antenna ground (cable shield) to the coach frame at the roof which would be a sufficient ground plane. My experience in tuning CB antennas is that it makes little difference in performance of the radio at CB frequencies around 27mhz. You may never get a decent swr reading of 1.5 or less, you just get the best you can with the installation you have.

In the fm ham bands, like 144mhz or 440mhz tuning the antennas is much more effective due to the shorter wavelengths. You can actually tune the antenna length to a quarter wave. A quarter wave antenna for cb would be 9 feet long, so they use a base coil typically to allow for rf matching. It is all a compromise and one not to put a lot of effort or expense into. Cell phones and some of the hand helds that run at higher frequencies are much more effective for communications rendering CBs obsolete.

Later Ed