Question about Cobra 29 WX NW ST 40-Channels Base CB Radio

1 Answer

Modulation with my linear

I have a Patroit 200 watt linear and a connex 4300hp , the radio has a dead key of 2 watts swinging about 110 watts. when i put the linear in line it seemed to work great but after a few transmissions , i started losing all my modulation , it dropped down to 2 watts swinging 10 watts , even when the box was turned off , i would turn off the radio for a few minutes and the modulation would return , then it would start to to drop and would lose modulation again, does anybody have a clue on what this may be, i was told it could be a filter in the amp......thanks

Posted by on

1 Answer

  • Level 1:

    An expert who has achieved level 1.

    MVP:

    An expert that gotĀ 5 achievements.

    Governor:

    An expert whose answer gotĀ voted for 20 times.

    Hot-Shot:

    An expert who has answered 20 questions.

  • Contributor
  • 40 Answers

The radio you are trying to fry your amp with is driving the amp to hard. that radio has a toshiba 80 watt final inside the radio you are killing your radio with the dead key at 2 watts it causes the final to overheat and shut down because it is not built to be turned down that much. its best to turn the radio back up and use the radio.

Posted on Mar 08, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

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

×

Loading...
Loading...

Related Questions:

1 Answer

What watt dead key and swing on CONNEX 3300 HP


A standard 3300 hp I seen get up to 40 watts peak,
normally I would turn the audio pot up all the way never snip anything and deadkey down to 2 watts. Than adjust for forward swing, I also never run a pwr mic. Good luck

Apr 20, 2015 | Connex CB Radios

1 Answer

No transmit signal


Does the unit work when it is not hooked up to the linear? The obvious choice is that you have blown finals in the RF output section of the radio.

Apr 02, 2014 | Connex 3300 240-Channels Base CB Radio

2 Answers

I bought a used connex 4300hp. i had it "so


IT could??? peak power, 14-15volts yeah.. the 4300 should put out 80w by itself.. as long as you have a low deadkey ie 1-5watts it should be fine. just don't put high wattage into an amp like that.. it will get hot QUICKLY.!!.. make sure your swr's are low low low.. 1.7:1 or lower... so your not getting reflected power... i would put a wattmeter with swrmeter like a mfj. or vectronic cross needle meter inline just to monitor it.... they go for $75 @ most places. Good investment... call email if need more help

Feb 06, 2011 | Connex CX-4300HP CB Radio

1 Answer

Can a 19 ultra power be turned down to 1 watt? If so where?


Yes it can, but it requires the addition of some components. It isn't really a straight forward install. It needs some reworking. In my opinion, not worth the trouble.

Sounds like you want to run a linear amplifier. If you really want to run an amp, get a better radio to do it. There really is no other reason to lower the dead key that low. Also, 1 watt might be too low. May not drive the amp well.

If you just want to make the radio swing, 1 watt is way way too low. You will have barely any carrier and the radio will sound like ****. That radio stock dead keys 2.5 watts. That's perfect for swing. Now you just need to have more modulation. Find DM1 and unsolder 1 leg and pull it out of the board. Now you will have full modulation. You will deadkey 2.5 and swing to about 15 watts.

If you want to run an amp, get a good radio. If you like cobra, get a cobra 29. They are fairly cheap, and sound amazing. As well it is real easy to lower the dead key in that radio.

Nov 12, 2010 | Cobra 19 Ultra II CB Radio

1 Answer

Galaxy saturn tubro 100 watt power is sticking after key up.


Not sure what you mean completely. If you mean, when you key up, it keys at 100 watts and stays, then this is probably not a problem.

If it doesn't swing, it is either the watt meter you are using, or you have the power up too high, or both.

I usually key my saturn turbo around 80 watts. You have to be careful with these radios. they get hot fast and when they do, they get whacky. Make sure you have a PC fan plowing on the heat sink on the back.

The higher the dead key, the less swing you will see.

Now as for the watt meter....

There are a few types of meters out there. The 2 most common are ones that read AVG, or average watts, or PEP or Peak envelope power, which in short terms is your Peak wattage. Some meters do both.

An AVG meter will not read peak wattage, or swing. So if you meter is an AVG meter, or is set to AVG, then it will not read swing, and will show you your dead key, and that's it. Some times the needle will move a little, but it is not showing your true swing.

All in all a PEP meter is a loose representation any way, because you really cannot get an accurate reading when there is modulation. But it's close enough. You would need a spectrum analyzer to really see what you are putting out with modulation. AVG with no modulation is a more accurate reading however you cannot see swing.

Now PEP while transmitting in SSB with modulation, would be accurate. Just not AM, but like I said, its close enough and is what every one goes by.

I don't know if your Saturn turbo has been modded or peaked and tuned but, you should see a max of about 170 to 200 watts swing on that radio if its been done right. But you will need a PEP reading meter to see that.

I wouldn't run it past 80 watt dead key for long. With that radio you should really only run what you need. For instance, when I am using mine, I start at around 70--80 watts, and do a check, and if it's not strong enough I bring it up a little, until the audio sounds good to who I am talking too.

Like I said, you have to keep it from getting too hot.

Nov 04, 2010 | CB Radios

1 Answer

I have a cobra 200 gtl dx and some one make modification on it to get more power and more modulation but i see in my books the modification to raise up on the board in front of my cb tell me to raise up...


you do not do it by resistance. To turn up the radio it is a variable resistor. What you do is connect a watt meter that can read PEAK or PEP watts AND AVERAGE or dead key watts.

First you check it on avg watts. Hook the radio up in line with the watt meter and set it on avg watts. key the radio. Stock is 4 watts. A lot of times when you peak a radio, you lower the dead key.(thats keying with no audio.) This allows you to get more modulation wattage, or swing wattage. If that has been done it will probably do 2 or 3 watts. If it has had the AM power raised in it, it could be more, this is no good. You want your dead key a bit lower.

Now check it on peak. Flip the meter to peak and make an AHHHHHHHHHHHHHHH noise into the radio. It should swing to anywhere between 15 and 20 watts.

You adjust the AMC while giving it audio and watching the meter on peak to adjust the modulation. 4 watts is legal modulation.

Feb 07, 2010 | Cobra 200 GTL DX 4-Channels Base CB Radio

1 Answer

Cobra 29 modulation modification


did you make sure the caps stripe is facing the back of the radio? If not, its the wrong way.

Also, don't use a 1/4 watt resistor because it will get too hot for it to last. use 1/8th.

changing the cap size will not change output, however it will change the tone. Bigger the cap, the deeper the tone of audio.

to be honest with you, high output mods are worthless in these radios. they are fine with out them. mosfets are unstable and are very dirty transmit finals. As well if you are planning to use a linear you may hit it too hard unless its a high drive, in which case you will need more then 35 watts swing to drive it fully. A stock cobra 29 that has been peaked and tuned, then the swing mod put in, 220uf e cap and 100 ohm resistor, which should give you about 2 watts, should swing to about 27 watts, and kick an amp in the pants.

I run a cobra 29 in my blazer with a dave made 5 pill, and I key on 6 pills and I near keyed on a 2x8. very close. All that I have done to the radio is peak and tune, (of course I have a few tricks with that up my sleave which I don't usually share with just any one.) and variable power, wich will control the dead key, which is basically a varible swing kit. I run it just under 2 watts, just enoug to get a 125 watt dead key out of the amp. The amps swings over 920 watts.

any more swing from the radio will beat up the pills in the amp.

Jan 06, 2010 | Cobra 29 LTD CB Radio

1 Answer

Cobra 29 classic "swing kit" ?


A swing kit is nothing more then a Cap and a resistor. There really isn't a different way to do a swing kit, unless you do variable power, which you don't need unless you are going to run a linear, and even then you can just set the dead key with a swing kit.

you need a watt meter, preferably one that reads peak and average watts. If not, average will be find.

Open the bottom cover of the radio. Hook the radio up to the watt meter, use a dummy load or have it hooked to the antenna. Never key the radio with an antenna or a dummy load.

Find VR4. Its toward the back right of the radio. Turn it all the way to the left. That increases your modulation.

Next find L14. it is at the back in front of the final resistor. While making a steady sound into the radio, just make an ahhhhhhh noise. Back the slug out of the tank until the needle hits peak. Don't move it out any more or you will over bias the final.

Now you will need a 220 uf electrolytic cap, and a 100 ohm 1/2 watt resistor, both of which you can get from radio shack. (this is your swing kit.

To the right of the tank slug is a jumper maked JP36. Us soldering wick to remove the solder and pull out the jumper. Now put the cap in it with the stripe facing the back of the radio.(that is very important. the other way you will blow the radio.) Solder it in place and cut the extra leads off. Now on the back of the board were you soldered in the cap, solder the 100 ohm resistor in between the 2 points.

The amount of resistance determines you dead key. you will be at about a 2 watt dead key which is good for swing and if you want to run a linear. The higher the resistor the lower the dead key, and the lower the cap, the higher the dead key.

That is your basic peak and tune with a swing kit.


Dec 23, 2009 | Cobra 29 LTD CB Radio

1 Answer

Tunring up a cobra 150 gtl/dx


Um... What?? This is hooked to a switch? CB radio by FCC regulations is only supposed to have a max of 4 watts total output. If you can flip it to 7 watts dead key, you are doing really good. It won't do much more then that. It sounds like its set up to run on a linear amplifier, which cannot have more then 3 watts dead key transmitting into it.

Dead key, and modulation are different. You may have a meter that only reads dead key, and won't see the modulation. This radio is probably swinging close to 15-20 watts. you need a meter that can read PEP, Peak envelope power. Cheap meters only read AVG, or average power, witch will only show your dead key.

7 watts dead key is really good for that radio.especially since stock only has 4 watts. you cannot get any higher then that without changing finals.

at 3 watt dead key, or 7 watt dead key, your modulation wattage is still swinging much higher.

Also, you will get more swing with a lower dead key any way, which is better if you want it to be loud.

Leave it alone. its probably set just right.

May 12, 2009 | Cobra 150 GTL DX Base CB Radio

1 Answer

Low output power


On the meter you are using, does it mesure Average power or peak envelope power?

This is very important to know when you are measuring.

AVG measures basically your dead key. It usually will very little if at all.

PEP measures your peak output, or swing. Modulation.

So even if you have a radio that has been peaked, on a meter that reads AVG, it will still read around 3 to 4 watts. And, if it has a swing kit in it, it will read even less. A swing kit lowers the dead key it increase modulation. Higher PEP.

For example. I peaked my cobra 29 and it does some where around 22 -25 watts PEP. I have variable power in it as well, but usually run the dead key at 2 watts because I have a linear. The Radio alone, when mesureing on PEP with key up at 2 watts, and then when you talk, swings to about 22 -25 watts.

If I flip the meter to AVG, it stays at 2 watts even with talking.

If you have one of those cheap pyramid meters, etc, they usually only read AVG.

Get a meter from radioshack. They have a fairly decent radio for the money. It reads both PEP and AVG and has SWR as well.

If the radio has been peaked and it has a swing mod, it will most likely be swinging to some where in the 20 watt range.

On a side note. According to FCC regulations, a CB radio is only allowed to transmit with 4 watts of final power. Most times the manufacturer will have it a hair under so that they are leagal.

Basically it is illegal to use a CB that puts out more then 4 Watts.

But its a free for all these days. There is no more funding to the FCC for monitoring CB radio, so they do not want anything to do with it. As long as you don't over do it, have over 50000 watts and terrorize a small community with RF, you can do what you want.

Now a days most cb radio's bought have already been peaked if you got it from a cb shop, or off a website that does it.

Apr 21, 2009 | Cobra 148 GTL 120-Channels Base CB Radio

Not finding what you are looking for?
Cobra 29 WX NW ST 40-Channels Base CB Radio Logo

294 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cobra CB Radios Experts

AnyMHz.com
AnyMHz.com

Level 2 Expert

489 Answers

Iron
Iron

Level 3 Expert

3018 Answers

Brad Brown

Level 3 Expert

13530 Answers

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

Answer questions

Manuals & User Guides

Loading...