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Cobra chrome no receive pure static
- Thread starter JNJ
- Start date
The issue with PLL showing 4.5V - remember that PLL's are SENSITIVE to voltages that are higher than their true power feeds.
They can get killed by static and higher votlages...
You're asking about Pin 9's voltage.
That depends on what voltage the chip is getting.
Most of the time the NEWER boards use 5V - to power the PLL.
So if you can verify that Pin 7 and Pin 11 are 5V or slightly higher, then don't worry.
The Voltage you see is ok if the PLL is running on 5V - doesn't need to be 8 to 9V - that "schematic" is from another time when CB-boom was big and people needed help understanding how the PLL worked and made channels.
These days, most of those systems are all 5-volt based - so you need to know if the RX to TX if Pin 9 DROPS voltage from 4.5V to 0V when it switches modes.
If it does not, suspect the keying circuit and or areas around that Mic jack.
The radio uses Pin 1 and GROUND and Pin 4 as SPEAKER return - which you SHOULD NOT hear the radio AT ALL when you pull the mike out of the jack - it should go dead. You say you're hearing noise, with no mike plugged in - so that is not right.
They can get killed by static and higher votlages...
You're asking about Pin 9's voltage.
That depends on what voltage the chip is getting.
Most of the time the NEWER boards use 5V - to power the PLL.
So if you can verify that Pin 7 and Pin 11 are 5V or slightly higher, then don't worry.
The Voltage you see is ok if the PLL is running on 5V - doesn't need to be 8 to 9V - that "schematic" is from another time when CB-boom was big and people needed help understanding how the PLL worked and made channels.
These days, most of those systems are all 5-volt based - so you need to know if the RX to TX if Pin 9 DROPS voltage from 4.5V to 0V when it switches modes.
If it does not, suspect the keying circuit and or areas around that Mic jack.
The radio uses Pin 1 and GROUND and Pin 4 as SPEAKER return - which you SHOULD NOT hear the radio AT ALL when you pull the mike out of the jack - it should go dead. You say you're hearing noise, with no mike plugged in - so that is not right.
