Question about Cobra 18 Wx St Ii Mobile Cb Radio

1 Answer

Radio sticks in TX mode after I let go of the button on the mic

I changed mics, tried three different antennas, sent it back to Cobra twice and they say there is nothing wrong with it. I used my swr meter on it and went to a professional and had him check the swr's.

Posted by on

  • williamhicks Mar 17, 2009

    Do you have a part number so I can replace it myself. I paid $69.00 dor this unit new and I already spend $36.00 in shipping it back to Cobra Corp. twice.

  • williamhicks Apr 06, 2009

    Do you have the relay part number so I can tell Cobra. The unit is still under a 2 year warranty. Or I can change it myself.

    williamhickstein@yahoo.com


×

Ad

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Genius:

    An expert who has answered 1,000 questions.

  • Master
  • 1,139 Answers

Hello williamhicks,

There is a relay in side of the cb that might be sticking. The problem is that this situation might be environmental. You say that you sent it back to Cobra twice for repairs. I think that the place you are sending it to differs enough environmentally so that the problem does not manifest itself. You can test this by exposing the unit to different temperatures, to determine if the internal relay is sensitive to variations in temperatures.

If you do find that the relay has become tempurature sensitive, you can order the part from Cobra, or strangly enough from Radio Shack, since they do carry the same part just by a different part.

I hope this helps,

Thank you,

Shuttle83

http://www.electron-age-technologies-llc.com

Posted on Mar 11, 2009

  • Henry McKelvey
    Henry McKelvey Apr 07, 2009

    Hello,



    I believe it's a solid state relay, It's been awhile, I tried looking for my copy of the schematic but I could not find it. Call Cobra, give them the model number and they should be able to find the part number for you.



    I hope this helps,



    Thank you,



    Shuttle83

×

Ad

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017

Ad

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Have a new cobra 29lx. Everthing works fine except for the SWR meter. Can't use the meter to adjust SWR. No matter what I do the meter stays the same. Sent to factory but they said nothing was wro


The SWR cannot be changed by rotating this knob. The SWR function allows you to determine the SWR or "match" of the antenna system and transmitter on a specific channel. The entire process must be performed whenever you want to know what the SWR is on a different channel. The SWR/CAL button toggles the meter between the CALIBRATE and SWR modes.
Set the radio to CH1. Press the SWR/CAL button. The radio CAL(ibrate) mode is now selected. Press and hold the mic PTT (or push to talk) button. Rotate the SWR knob as needed to adjust the meter indicator until it is on the SET mark on the dial. The meter is now calibrated for this channel.

While still holding down the mic PTT, press and release the S/RF SWR CAL button to the SWR setting to read the SWR on the meter.



This entire process should be done for Ch 20 and Ch 40. You must go through the CAL procedure for EACH channel before attempting to read the SWR.


Changing the SWR requires that the antenna be lengthened or shortened until such time that the SWR can be reduced no further. Typical SWR across the band may be:


CH1 - 1.5:1, CH20 - 1.1:1, CH40 1.5:1


or


CH1 - 2.2:1, CH20 - 1.7:1, CH40 2.3:1


The "dip" in SWR on CH20 is typical, as the antenna is the perfect length on only one channel - it will be come slightly too long or slightly too short as you tune up or down from CH20. The further away from CH20 you go, the poorer the SWR will be. You can "slide" the dip to any channel you prefer - say CH8. If you tune for lowest SWR on CH8, You might see CH1 with a 1.2:1 SWR, CH8 at 1.1:1 SWR and CH40 at 2.5:1. All are acceptable - sort of. Many manufacturers say up to 2.5:1 or even 3.0:1 matches are ok, There's no reason a quality antenna can't be tuned for optimum SWR in the middle of the band (CH20) to have less than a 2.0:1 SWR on CH1 or CH40, unless there is a ground issues or bad cable / antenna / connection somewhere.


You can view the manual here. I hope this helps & good luck!

Nov 30, 2012 | Cobra 29 Lx Full-featured Cb Radio

1 Answer

How do I calibrate my cb to match my antenna


1. You calibrate the antenna to match the CB rather than the other way around. Some antennas can be adjusted while others cannot. This should not cause a problem since the ones that cannot be adjusted generally don't need adjusting. The ones that can be allow for fine tuning to get a better match.

2.To match your antenna to your CB you set the SWR (Standing Wave Ratio) to it's lowest possible setting. SWR is the ratio of power that gets out through your antenna versus the reflected power that gets sent back to the CB. You want to get the most power to go out, or forward, through the antenna as this drives the signal that others receive. To set your SWR;

3.Connect an SWR meter between the antenna and the CB using a short piece of Co-ax cable. Set the switch on the meter to Forward Power. Key the CB and adjust the dial on the SWR meter until the needle of the meter is fully forward. Release the transmit button and change the switch on the swr meter to Reflected Power. Key the mic again and note how high the needle goes. If the needle doesn't go into the red it's safe to use but the lower the reading the better.

4. To bring it down check your antenna. Some antennas have a telescopic tip that can be extended or reduced by loosening a nut near the top. Try extending it fully and repeat the procedure at paragraph 3 above. If your SWR rises then try reducing the antenna length and check again. It's a matter of finding where you get the lowest swr by making smaller adjustments from the best of the 3 settings above.

5. You'll probably find that when you get a low SWR on one channel it will be higher on other channels. This is because of the frequency difference. Unless you use one channel nearly all the time, it's best to set the swr on the middle channel so if you have a 40 channel CB set the SWR on channel 20. The further you change up or down the higher the SWR will increase but it should be still within the safe range. If you set the SWR on say channel 1 the SWR will be twice as high when you change to channel 40 than it would have been if you set it on channel 20.

6. Most people never check their SWR so if you're using a commercial CB antenna, rather than a home made one, it should be factory set to give a reasonable match so if yours cannot be adjusted it's probably matching ok. A more common problem to look out for is the connection from the antenna to the CB. Make sure that the screening wire and the centre core are not touching. Even a single strand of the screening touching the centre wire will cause screeching on your transmission and before long will cause your CB to stop working. 73s and enjoy your CB.

Apr 03, 2011 | Cobra 29 LTD CB Radio

2 Answers

I have a swr meter and i would like to no how to ues it


Goto channels 1 20 and 40 and do the following.... this a generic calibrate all swr meters have different buttons different style of meters etc...
set meter too the set/cal/fwd position. key mic adjust the meters needle to cal spot should have an arrow or red line etc. then change switch to swr/rev too show your reflected swr.

ch 1 is longer wavelength than ch 40.
if ch 1 is good swr and ch40 is high swr-- then make antenna shorter
if ch 40 is good swr and ch 1 is high swr-- then make antenna longer.
then try to get a good balance between the lowest freq and the highest freq./ch.
-- anymhz(dot)com ---- Radio Shop

Dec 06, 2010 | Radio Communications

1 Answer

Every time I press my MIC to speak into it the red lights on the RX/T and ANT light come on alerting me of a problem. How can I fix this.


RX/TX light should change to red, however the ANT light is a bad light. This means that your antenna is not adjusted properly. Do not key the radio or talk on it for any other reason then to check the SWR and tune the antenna. If you have the manual that came with your cobra 29, there is a section that explains how to check the SWR. And the manual for the antenna, it will explain how to adjust it.

If not, here is how to do it.........

How to check the SWR on a Cobra 29

Step 1. Find out what your current SWR is on the center of the band.

  1. Turn the radio to channel 20.
  2. Set the S/RF SWR CAL switch to CAL.
  3. Turn the CAL knob all the way counter clockwise.
  4. Key the radio. Do not talk into the mic.
  5. While holding the mic key, turn the CAL knob to the right until the needle reaches the CAL mark on the top right of the meter.
  6. Now flip the S/RF SWR CAL switch to SWR while still holding the key on the mic.
The needle should fall. Where ever the needle is while holding the key is your SWR reading on channel 20. It should be as low as possible. If its a reading of 2, then its not gonna kill the radio but is border line. Any higher and its bad. Using the radio like this will damage the final output transistor. If its less then 2 this is better. You want it to be less then 1.5 or better.

The ANT light may come on with an SWR of 2. running the radio with an SWR of 2 shouldn't hurt the radio, but I don't like to mess around. Get it as low as possible.

How to adjust the antenna for SWR

The length of your antenna will change your SWR. SWR is basically how much RF energy is not leaving the antenna and getting reflected back into the radio. That's why it hurts the radio when its high. An antenna has to be the right length, matching the length of the radio waves in order for it to radiate all of the RF energy out of the antenna.

Most antennas have a way of lengthening or shortening the antenna. If its a mag mount antenna with a metal whip, there is probably a set screw that when loosened, will allow you to raise or lower the whip. If its a fiberglass antenna, under the rubber cap at the top is how you raise or lower the antenna.

Figuring out if your antenna is too long, or too short

Here is how to know weather or not you have to lengthen or shorten your antenna.

  1. Take an SWR reading as explained in the first step on channel 1. Write down the SWR for reference.
  2. Take another SWR reading on channel 40. Again write it down for reference.
Now if the SWR is higher on channel 1 then on channel 40, its too short. You need to make it longer.

If the SWR is higher on channel 40 then channel 1, then the antenna is too long. You need to shorten it.


Make small adjust ments about an 1/8th to a 1/4th inch at a time. each time checking the difference between channel 1 and 40.

You will know when you are a good match when there is little to no difference between channel 1 and 40's SWR. Once you are satisfied that the difference between 1 and 40 is about the same, and much lower, then turn the radio back to channel 20 and take an SWR reading.

You will now find that the SWR on channel 20 is really low. Most likely under 1.5 or better, Almost nothing on the meter.


Here is a Meter Key, so you know what you are looking at.
2d03348.jpg

Oct 11, 2010 | Cobra 29 LTD CB Radio

1 Answer

WHEN I PLUG IN VERY LITTLE RECEPTION WEATHER BAND COMES IN FINE. SIGNAL DOES NOT MOVE EVEN WHEN KEY MIKE, CAN'T SET SWR VERY DIM EVEN WHEN ADJUST DISPLAY


1st. You cannot "set" the swr. The swr is not set on the radio. The antenna must tuned to attain an appropriate SWR reading.

2nd, If this doesn't solve your problem then you could have a worse problem. If there is a problem with the mic such as a break in one of the wires, the radio's receive will be off until you put a good mic on it. Try a different mic, and see if the receive comes back. Then check and see if your transmitting better.

As well, your meter could just be bad, as well your coax or antenna. Your receive could be poor if the antenna is not tuned to lowest SWR.

If it has been working up till recently, and you have "set" the SWR on the radio, which is not what the SWR function is for, because you don't set SWR on the radio, you could have been using the radio with the SWR super high and blown the final or other sections of the radio out.

SWR is basically signal reflection. If the antenna is not the right length, it will reflect energy back into the radio and damage it over time. The more an antenna is off from the correct length, the more reflect you will get.

The meter in the radio is used to determine how much reflect you are getting. You ideally want to have the lowest SWR possible.

To check the SWR, you set the meter switch to CAL. Key the mic. while holding the mic key down, turn the CAL knob up until the needle is at the little triangle at the top right of the meter marked by "CAL", Then while still holding the key, flip the meter switch to SWR. where ever the needle is at that point is your SWR.

You want ch 20 to have the lowest SWR. If the swr reading on channel 40 is higher then channel 1 then your antenna is too long. if it is higher on 1 then 40, its too short. Make small adjustments until 1 has almost the same reading as 40. then check ch 20 and it should be real low.

As I have said, if you haven't tuned your antenna as I have just explained, and have been using it as is, the possibility is high that you have already hurt the radio.

Although it could also have a bad meter. Use an external meter to read the SWR.


Other things to check. Make sure cable connections are tight. Make sure coax is not damaged. try another antenna.

Aug 24, 2010 | Cobra 29 LTD CB Radio

2 Answers

Cobra 18 wx st receives-wont transmit


Take the cover off, flip it over solder side up, check all solder joints for cracks, cold solder joints, check the safety diode where it comes in the radio, before I go further, can you pick up the weather channel?...Does the PA work?...need to check the pre-driver and finals,audio chip, hook up the power meter using a coax three foot jumper from the output from radio to the input of the watt meter, then the antenna, first check the SWR, on the scale on the meter to cal/swr mode,adjust it to spec, then while still keyed down turn the dial to SWR,if it is the safe range your ok,then turn the Dial to 10 or 20 watt scale and key the mic. Does it have any wattage? If not suspect the finals, they are located on the back rail, if it does have RF then its the audio chip, its located on the right side rail facing you,closest to you.remove it and replace it with same ....hope this helps....

May 21, 2010 | Cobra 18 WX ST 40-Channels Base CB Radio

3 Answers

Dont know how to use the swr meter on my radio


With radio turned on

1. Switch the first switch (S/RF SWR CAL) to CAL setting
2. Key mic up &
3. Turn SWR CAL knob while still keying mic until the needle is on the red CAL arrow at the far end of the meter scale. Unkey mic.
4. Switch the first switch back to SWR setting.
5. Key mic up again and record SWR reading and adjust as needed.
6. When done adjusting put switch back in the S/RF setting for normal operation.

Do not flip the switch with the mic keyed up.

Jan 19, 2010 | Cobra 29 LTD CB Radio

1 Answer

My antenna light stays on even after I have realeased the mike


Try checking the SWR's on channel 1, 20, and 40. The SWR's will change from the low channels to the mid channels to the high channels. The key is to make sure that the SWR's are around 1 or less at all three points. If the light goes out when checking one of them, then the problem is most likely the SWR's. If the light stays on when checking these channels, the issue might still be the SWR's but I would look at the grounding on the antennas. When holding the talk button on the mic and switching from calibrate to swr, can give a false reading. This is due to the calibrate circuit remaining open until you release the talk button. Take the SWR reading by releasing the Talk button on the mic after calibrating then pressing the talk button again after switching back to SWR. This will be the most accurate reading. From everything you described, I would be looking for a grounding problem with the antennas or coax, possibly even a rub though on the coax somewhere in the dash.

Dec 20, 2009 | Cobra 29 WX NW ST 40-Channels Base CB...

2 Answers

"squeak" when transmitting


Make sure you have a good ground for the radio and antenna. How long is the antenna coax if a little to long and you have extra what did you do with it coil it if so uncoil it and lay it out try it. If no luck I would shorten the coax and recheck your SWR.

Jun 22, 2007 | Midland 1001Z 40-Channels Base CB Radio

Not finding what you are looking for?
Cobra 18 Wx St Ii Mobile Cb Radio Logo

Related Topics:

111 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cobra Boating Experts

RFburns

Level 1 Expert

15 Answers

Donald DCruz
Donald DCruz

Level 3 Expert

17130 Answers

yadayada
yadayada

Level 3 Expert

79865 Answers

Are you a Cobra Boating Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...