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Rci2950keys up but no power gos out

Theres no dead key

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Check to make sure that the radio is on AM not FM or LSB or USB. There is Also a power control on the front of the radio turn it up half way and see if this might be your problem.If it still does not have any power out put,put the radio on usb or lsb make sure that your modulation is turned up and talk into the mike to see if you have any output.If you do have output on ssb mode the am regulator is most likely bad. ( Q 51 & Q 53) wich is located in the right hand side of the radio.

Posted on Nov 12, 2008

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How to adjust cb for linear amp installation

That is a broad question. It depend more on your choice of amp. Typical setup cobra 29 with 2 watt dead key or carrier into 150 watt amp. We must pay attention to the total swing a more powerfully radio could still hurt this size amp if the pep wattage was to hi no matter the dead key being low. The cobra is no threat to this size amp as long as dead key is reduced.

May 26, 2014 | Radio Communications

1 Answer

How do i adjust dead key on a cobra 25 ltd classic cb

The only "adjustment" is the AM POWER trimmer. Lowering this will lower your dead key but will also lower your "swing" power. the TX circuit must be modified to lower the dead key and maintain full output. there are many articles on the web for such modification.

Apr 12, 2013 | Cobra 25 LTD 40-Channels Base CB Radio

1 Answer

What is the dead key adjustment # on a midland 5001z cb ?

amps like the smaller wattage so they can push out more power but some amps like the 3 watt figure so they can push out more power. go to and look up your radio. the schematic is there but I don't remember if there is a service manual for it.

Dec 27, 2012 | Midland 1001Z 40-Channels Base CB Radio

1 Answer

Need to know where to set low power set up for amp thanks

There is no specific dead key setting for an ampifier. Each amplifier requires different dead key to operate at it peak effeciency AND to sound the best it can. If I knew what type of amp it was I could give you a better idea. Just for a reference point I will give you these numbers. For your basic amplifier ( 2 pill - 4 pill non high-drive) you could safely set the carrier at 1 - 3 watts. This is why the majic number for most people is a 2 watt dead key. For a High-Drive amplifier you really have a broad range of settings for deadkey. Generally anywhere between 2 - 8 watts. Some can even handle 10 watts. This DOES NOT mean that they need a HIGH dead key to operate properly. Just FYI, what you run into with improper dead key is either a really choppy, splattery, overmodulated sound with a deadkey that is to low, OR, a really pinched up, tight sound with a dead key that is to high. Also, a HIGH dead key can cause an amplifier to over heat, causing the transistors (pills) to fail prematurely.
To set your dead key "properly" you really should have a technician "match up" the radio with the amplifier. This means, he will hook up the radio and amp that you plan to use with one another in line and tune (set dead key) the radio to "match" the amp. This will give you the optimal audio and performance without overdriving the amp.
Hope this helped. Lost Jeep, Athens GA, 10-7 !!

Feb 17, 2011 | Connex 3300 240-Channels Base CB Radio

1 Answer

Superstar 121 with astatic power mic and texas star dx 500 power..when I key up to talk they say I sound like I'm a ways from the mic, but I have a loud roger beep...any ideas....mic?...

try a stock mike or a noise canceling one. Hard to run power on top of power. And see what your radio is dead keying into the radio...usally with a 500 it can take up to a 6 watt dead key.

Nov 10, 2009 | Superstar SS-121 120-Channels Base CB...

2 Answers

Just want to know if i should use my ll203 amp in am or ssb mode when running with a cobra CB radio?

What radio?? Does it have single side band(SSB)? If not, then don't use SSB.

AM - amplitude modulation
SSB - single side band.

If you have SSB, there would be a switch on it to transmit in SSB. If not, it is AM only.

Second, Has this radio been worked on to be able to run on an amp? If not, you will blow the amp.

A CB radio transmits dead keys with 4 watts of power, and transmits with 4 watts of audio.

a 4 watt dead key is too much for a linear amp. You will smoke the transistors. Also, 4 watts of audio is not enough to drive it properly. You won't get full power.

The dead key needs to be around 2 to 2 -1/2 watts,or what ever makes the linear dead key half its peak wattage., and the modulation (audio) turned up all the way.

It doesn't sound like you know too much about CB radio's. Not a big deal, you can learn. For right now you may want to take it to a cb shop and tell them you want a peak and tune, and set up to run a linear.

You can find CB shops usually at truck stops. Some area's they are other places. Check the internet for local shops.

Oct 31, 2009 | Galaxy Radios DX-959 40-Channels Base CB...

1 Answer

Tell me how to turn the raido power down to 1 watt so i can hook up my 350 watt liener? i need to find the schmatics so i can find the right knob to twist

There are no knobs for AM power in the cobra 29 LTD. Soldering 2 parts inside the radio is needed to do this. If you are not comfortable with soldering inside of the radio, take it to a technician.If you feel you are up to it, here is how you to do it.

First make sure VR4 is all the way to the left. This will turn your modulation to full and will make your audio louder.

Next you will need a 220 uf 35 volt capacitor and a 1/2 watt 100 ohm resistor.

Now remove JP36. It is located right in front of the final transistor in the back right that is bolted to the heat sink.

put the capacitor in its place with the black tab facing the back of the radio.( this is most improtant because if you don't face it the right way you will blow your radio). Solder it in place.

Next on the trace side of the board, where all the solder joints are, solder the resistor to the spots where the cap was soldered. So the resistor is in between the 2 points of the capacitor.

Now your dead key will be at 2 watts. Now, you did say you wanted 1 watt. From my experience, 1 watt is not enough. you will under drive the box and blow the pills in it.

If in fact you do need only 1 watt, you have to play with what size resistor you put on it. if you increase the value of the resistor, you will get a lower dead key. If you lessen it, it will make the dead key higher. Get a multi pack of 1/2 watt resistors if your going to do this.

BUT** 2 watts should be what you need.

So you know. There are 2 types of wattage outputs in an AM radio. There is carrier signal or dead key, and then there is modulation or swing.

Your radio is going to do 2 watts of a carrier signal or dead key, and when you talk the meter will swing up when you talk if you have peak reading meter. it it only reads average, it will only show your dead key with only a swing of about 4-5 watts.

For low drive amplifiers, the dead key is usually all that needs to be set. The swing should be turned up (thats why you turn VR4 all the way to the left) witch will give you just over 20 watts swing. this will drive the box good. Any where between 20 and 35 watts will dive most boxes good.


Oct 09, 2009 | Cobra 29 LTD CB Radio

1 Answer

Full power with zero modulation

you possibly have a faulty microphone, if the amp is keyed to transmit and there is not audio to modulate. Try another mic

Sep 19, 2009 | Galaxy Radios DX-959 40-Channels Base CB...

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

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