cobra 29 ltd no modulation output.

[guitar_199]

IN all seriousness, there is a "lot of lesson" in this posting!!!

10.240MHz ÷ 1240 = 10 KHz (channel spacing)
10.240MHz ÷ 2 = 5.15MHz x 3 = 15.360 MHz
Channel 1 = .91(MHz)
Channel 40 = 1.35(MHz)
Transmit oscillator is 10.695MHz
10.695MHz + .91 MHz+ 15.360MHz = 26.965MHz
10.695MHz - 10.240MHz = 455KHz

 

[Handy Andy]

I have a vobra 29 ltd classic yhat has a connex board in it j was using the radio had it in cig ligter and it just quit making modulation if u turn on the weather setting it sounds like the guy is off frequency and through my talk back I can hear myself but it sounds like its off frequency bit it puts out signal when u key up

The audio - if it sounds "Pinched" like you describe - it may be from the output cap from the audio chip, these can "short out" from the cigarette lighter plug to vehicle potentials. How? From RF voltage differences - too much floating RF or noise potentials differences between the inside seats and the outside world, especially if it's using a Mag-mount antenna - can blow the 330uF cap from the RF voltage floating about.

Quickest way to check is to see if the Audio Chip heat soars up really quickly - means the cap or the output is shot, the chip will be next if it's not repaired.

• Not to beat up a sore subject of cigarette lighter use,
• But the problems you are having are prone to operations and installs like you describe, they are the worst in supplying the best possible means to power the radio.
  • In newer Hybrid vehicles - very little left to chance in only to make the radio fail for work or even provide any service in some instances due to the noise and lack of proper RF grounding.

But, then, if it can work for calling or help or keep you from losing time from bad traffic jams - then it can pay for itself - but remember to tell them that cigarette lighter plugs are only a temporary solution and will pose problems for any equipment that uses them - except for their main purpose to supply power to operate stuff inside the vehcile.

 

[08fatbob]

Thanks for the response Loosecannon.

Could not have done it without your help. As i was going through checking voltages I found another shorted cap at C67. All is fine now. RX/TX is as it should be. Thanks for other responses too, regardless of the sarcasm, and condescending attitudes. ., .

How did you know c67 was shorted? How did you test it? Just curious. Having the same problem. Trying to learn. Thanks