China made Cobra 148gtl clarifier problem.

[kopcicle]

 

[nomadradio]

A PLL that won't lock is usually missing one of the inputs to the PLL chip.

45-plus years of experience with PLL circuits, and I have never learned to troubleshoot them without a 'scope.

Do you have any kind of radio that can receive 10.24 MHz?

Putting a coax jumper on it, and using the tip of the plug on the far end of the jumper as a "sniffing" antenna would tell you if the 10.24 MHz crystal is running. If it quits for any reason, you'll see that 25 or 26 MHz 'stuck' frequency.

Same goes for the 11.325 MHz crystal. If it quits for any reason you may see this symptom.

For that matter, failed solder connections on the circuit board are always a possibility in a Galaxy.

73

 

[loosecannon]

i don't want to hijack the thread, but when i see 148gtl clarifier threads, i like to make sure that this info is in them:

you don't need to remove R44, or jumper R174, or jumper D51 if you just want the clarifier to track on transmit as well as receive.

all you need to do is remove D52, and move the receive only voltage wire on the clarifier pot over to a constant 8 volt source, such as pin 1 of the MB3756 voltage regulator.

doing the mod this way will disrupt the tuning of the radio far less, and the radio won't have that crazy amount of slide.

we have to remember that all of these clarifier mods were created in the age when 'sliding' was very popular, and everyone wanted to be able to slide over whole channels or more.

nowadays, unless you have a specific reason for wanting it, there is no reason to have that much slide, and your radio will be more stable.

yes, the radio still needs to be aligned after the mod, but it will just need slight tweaks.
LC

 

[American-Vulture]

A PLL that won't lock is usually missing one of the inputs to the PLL chip.

45-plus years of experience with PLL circuits, and I have never learned to troubleshoot them without a 'scope.

Do you have any kind of radio that can receive 10.24 MHz?

Putting a coax jumper on it, and using the tip of the plug on the far end of the jumper as a "sniffing" antenna would tell you if the 10.24 MHz crystal is running. If it quits for any reason, you'll see that 25 or 26 MHz 'stuck' frequency.

Same goes for the 11.325 MHz crystal. If it quits for any reason you may see this symptom.

For that matter, failed solder connections on the circuit board are always a possibility in a Galaxy.

73

Not getting the 10.240 signal to the pll .even put in a different one. didn't make any difference.Do not care about clarifier....just put it back to stock.

 

[American-Vulture]

A PLL that won't lock is usually missing one of the inputs to the PLL chip.

45-plus years of experience with PLL circuits, and I have never learned to troubleshoot them without a 'scope.

Do you have any kind of radio that can receive 10.24 MHz?

Putting a coax jumper on it, and using the tip of the plug on the far end of the jumper as a "sniffing" antenna would tell you if the 10.24 MHz crystal is running. If it quits for any reason, you'll see that 25 or 26 MHz 'stuck' frequency.

Same goes for the 11.325 MHz crystal. If it quits for any reason you may see this symptom.

For that matter, failed solder connections on the circuit board are always a possibility in a Galaxy.

73

I just found a service manual for the cobra 2000.That will help me trace the problems.