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I am getting high swr readings on my base station antenna. It is a 102'' whip and I don't think I have it connected properly. I connected the center copper wire to the antenna but did nothing with the outer mesh type wire surrounding the copper wire. should this be grounded to the antenna in any way? I must add that the building it is mounted on is made of wood.

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What i would do is go and buy a real cb antenna mount like a mirror mount and get a peice of sheet metal and screw the mount to the metal and screw that to the roof or side of the house and you should buy a spring that will also help with the swr and if you by the mount you can just screw on a standard pl259 connector

Posted on Apr 17, 2009

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1 Answer

Swr on channel 1 and 40 are over 3, what can I do?


Check your antenna. Make sure it is getting a proper ground. If mag mount; make sure base of antenna and where you put it are both super clean. Check where whip goes into coil or base. Make sure all allen screws are tight and whip is not either all the way down to the base or up to the top. If antenna is mounted; make sure that it has a good ground. You might have to remove some paint around the base to get a good connection. DO NOT TRANSMIT WITH A HIGH SWR. YOU CAN BURN OUT THE EXPENSIVE POWER OUTPUT TRANSISTOR. Hope it helps.
Tom

Jul 15, 2012 | Cobra 25 LTD 40-Channels Base CB Radio

1 Answer

I have a Cobra 29 ltd. When I key up my ant light turns red and when I release I sometimes will still be keyed up and light still red.


Sounds like extreme SWR. Check your antenna. Make sure it is getting a proper ground. If mag mount; make sure base of antenna and where you put it are both super clean. Check where whip goes into coil or base. Make sure all allen screws are tight and whip is not either all the way down to the base or up to the top. If antenna is mounted; make sure that it has a good ground. You might have to remove some paint around the base to get a good connection. DO NOT TRANSMIT WITH A HIGH SWR. YOU CAN BURN OUT THE EXPENSIVE POWER OUTPUT TRANSISTOR. Hope it helps.
Tom

Mar 06, 2012 | Cobra Radio Communications

1 Answer

I have a Radioshack trc-487 cb radio with weather band . I would like to turn up the modulation... Peak and tune... get better reception... anything... I would like to know the internal parts I have to...


Hello Randy, do you have a fiberglass or stainless whip? What is your SWR & power meter readings now? --- The stainless whip may be creating a feedback and picking up static from transformers. Do you have a power microphone? If so you need to use a modulation meter to set it for 100% modulation. It could also be causing the crackling, that or your engine alternator.

A 1:1 SWR implies a perfect match between all elements of the antenna system...this is what you want. If an antenna system is not working well, the power reflected by the antenna will travel back through the transmission line and arrive at the output of the transceiver. From a practical point of view, SWR numbers in the range from 1:1 to 1.5:1 are considered to be very good, meaning that the antenna is radiating most of the power sent to it...

I would not recommend tweaking the boards on the realistic radios. You can however tune your whip. Start by making a base coil with some copper wire, 14 gauge will work. Run one end under the whip mount end and then tightly wrap the wire around the base of the whip. Experiment with 20 - 30 wraps for best performance & SWR.

The Astatic 575M6, or the Sadelta MB-4(hard to find) are very good power microphones that will help with modulation and peak power transmissions. Let me know if you need more help with tuning, if the "crackling" is still there.

Here is a link for your radio, in case you don't have one.

http://support.radioshack.com/support_electronics/36554.htm

Nov 16, 2011 | Radio Communications

1 Answer

I have a cobra ltd 29 bt hooking to a 102 inch whip and cannot get m swr readings down under 3 or it will go up higher then the calibrate triangle instead of down. my antenna is mounted with a gumdrop...


  • Sounds to me like you need to check the connectors and connections on that coax. A cobra29 and a 102" whip is a simple enough set up and should not produce that high of SWR unless the coax or the connectors on the coax are pretty messed up. Also i recommend putting an SWR meter in line.
  • The meters on them Cobras can be accurate sometimes but I trust an inline meter much more.
  • Ground it again to make sure.
Regards, Tony

May 17, 2011 | Cobra 29 LTD CB Radio

1 Answer

I have a Midland 1001Z 40-Channels Base CB Radio and a Magnetic-mount CB antenna. 29" stainless steel whip and 6" spring. About 46" high overall. All bought from /www.thesource.ca in Alberta...


Try Grounding it better. Its supposed to equal 8.5 ft.(102 inches) but the coil may make that in all.You can clip like 1/8 inch off at time until it goes 2.1 Swr. Thats a good standard. 1.5 SWR is desired. If it don't have a coil with it that may be the problem. You could turn it into a 8.5 ft. antenna by buying a 102" inch whip to screw into the base of your antenna, it depends if it holds or not. You could build you a matcher like this with a solder gun+solder and 2 resistors. Get you a box with 2 female cb antenna inputs. Drill a hole for both Cb antenna inputs into box. Place them into holes screw nuts down snug. Run a copper wire inside to both grounds or a plate somewhat. Run a thick gauge copper wire from center cb ANT INPUT(2) to other input of ANT INPUT(1). Solder 2 100 ohms in parallel from input to Ground. If you could take apart your radio(eliminating the box idea). Just Solder 2 (100 ohm) resistors to your Antenna output then put it back together. 50 OHM MATCH HERE Is the main idea. I've used 75 OHM Tv coax and reduced SWR.

Apr 04, 2011 | Midland 1001Z 40-Channels Base CB Radio

1 Answer

Im having a problem with people hearing me on my CB. I can hear people fine and it comes in real clear, but they can't hear me at all, i mean they can but its just that its so low they can hear me. It was...


Tune your antenna. If he took the metal whip out of the base, then he messed the tuning all up.




It is important to tune your CB radio antenna to the proper length. The length must exactly match the wavelength of the frequency you transmit on. Or be really really close.

All Cb antenna's have a way to adjust the length of the antenna. If it's a mag mount, the metal whip can be slid in and out of a metal collar. Usually a set screw. If its a fiberglass whip, the way to tune it is on top. It either has a small metal rod with a set screw to adjust the length, or it threads in and out to adjust length.

Either type you have it will need to be adjusted for proper length. Here is how to tune the antenna to lowest SWR.

Some radios have a built in SWR meter. Some do not. If yours doesn't have an SWR meter, then you have to use an external SWR meter. Radio shack carries one, and you can find them cheap on ebay.

If you have a built in SWR meter or external, the procedure is the same:

1. Turn the radio to CH 20.(This is the center of the band.)
2. Switch the meter switch to CAL. (CAL stand for calibrate.
3. Key the radio. (Important. Do not talk while keying the radio.)
4. turn the CAL knob up until the meter hits the CAL mark.
5. Now while still keying the radio flip the meter switch to SWR.

Where the meter falls after that point is you SWR reading. If its above 3, that is real bad. 2 is not gonna kill your radio but its not the greatest. 1.5 and under is a good place to be, but the lower the better.

If your SWR is high, Here is how to find out if your antenna is too long or too short.

1. Turn to CH 1
2. Repeat SWR procedure. You must calibrate every time you do it.
3. Remember the SWR reading.
4. Turn to CH 40.
5. Again repeat SWR procedure.
6. Compare the reading between CH 1 and CH 40.

Now if the SWR is higher on channel 1 then channel 40 your antenna is too short. You must make it longer.

If the SWR is longer on channel 40 then on channel 1, then the antenna is too long, you need to make it shorter.

Make height adjustments about an eight inch at a time, and take reading each time.

once the SWR is significantly lower and the reading on channel 1 and 40 are about the same, you a about matched. At this point turn the radio to the center of the band, channel 20 and take an SWR reading.

You should now have a low SWR reading, 1.5 or under. If you are 1.5 or under, you are good to go.

If you cannot get the SWR to an appropriate level, there may be an antenna problem.

Nov 12, 2010 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

I can't get the swr value close to 1 it's over 3 what am i mising


Several things are working against you.
1 Antenna location= Needs to be in CENTER of car or truck, and high. no grounded metal can be next to the element (the hot/positve part of the antenna)

2 the only way to really ground the antenna is by having a flat metal ground plane under the antenna. DC grounding does NOT do this, that is a misunderstanding.

3 make sure you use a tunable antenna. I have found the wilson's to be very easy to tune and performe very well, for a base loaded antenna.

4 in short a wilson or k40 magnet mount placed on the very top of the roof in the center will have a perfect ground plane. Then shorten or lengthen the steel whip to ajust your SWR's. You will get the best results this way. This is the ONLY way to achevie good performace.

5 I will say this the absoulte best antenna is the 102"steel whip, if you got the clearnce and dont mind it hitting tree limbs put it on a big magnet mount with a spring at the base and youll have a perfect antenna. But the wilson is shorter and easier to tune.

May 15, 2010 | Cobra 29 LTD CB Radio

1 Answer

High swr's on cobra 29 ltd


Check your antenna. Make sure it is getting a proper ground. If mag mount; make sure base of antenna and where you put it are both super clean. Check where whip goes into coil or base. Make sure all allen screws are tight and whip is not either all the way down to the base or up to the top. If antenna is mounted; make sure that it has a good ground. You might have to remove some paint around the base to get a good connection. DO NOT TRANSMIT WITH A HIGH SWR. YOU CAN BURN OUT THE EXPENSIVE POWER OUTPUT TRANSISTOR. Hope it helps.
Tom

Feb 09, 2010 | Cobra 29 LTD CB Radio

1 Answer

Swr too high


Check your antenna. Make sure it is getting a proper ground. Check where whip goes into coil or base. Make sure all allen screws are tight and whip is not either all the way down to the base or up to the top. If antenna is mounted; make sure that it has a good ground. You might have to remove some paint around the base to get a good connection. DO NOT TRANSMIT WITH A HIGH SWR. YOU CAN BURN OUT THE EXPENSIVE POWER OUTPUT TRANSISTOR. Hope it helps.
Tom

May 26, 2009 | Cobra 29 LTD CB Radio

1 Answer

Non grnd steel antena


I assume your coax is not hooked up properly or you have some kink of a short in your antenna connection ( thats if your cb is working properly ) Radio Shacks Information that suggested that the 102" whip is the perfect antenna is their opion only as I prefer to recommend a full wave antenna system to my customers, but I do assure you, the 102" whip does work well if it's properly installed. I have found the main problem in the 102" whip installation is when the center hole is cut to install the antenna, it's not cut big enough, which grounds the antenna. It's not suppose to be grounded in any fashion to the automible chassis. The ground of this antenna comes from the 3 screws mounted around the outside of the antenna mount. Check that for sure. If you can't correct the problem. write me back at this web sight of direct at wyoed1@aol.com. Good Luck
Ed
NC Electronic
Mills, Wyoming

Dec 19, 2007 | Uniden Bearcat Pro PC68XL 40-Channels Base...

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