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