MB8719 & RCI8719 PLL

Extra Channel mods for the MB8719 PLL



If your radio has a MB8734 pll change it to a MB8719

[MB 8719 mod chip]


COBRA 140 , 142 GTL , PRESIDENT WASINGTON AND McKINLEY AND P400

1) Mount 2 SPST toggle switches in a good loacation on the radio.
2) Locate and unsolder the 11.1125mhz Crystal and replace it with a 11.3258 mhz crystal.
3) Locate pin 10 of the mb8719 chip.Cut the trace that is connected to it.
4) Solder the wires onto the switches and pins of the chip like in the diagram above.


COBRA 148 , 2000 GTL , UNIDEN GRANT AND MADISON

The mod is basically the same for these radio EXCEPT that there is no PC trace going to pin#10 on this PLL.
On the Cobra 2000gtl you will find a MB8734 pll replace it with a MB8719 PLL


Full Color pictures of the channel mod

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Channel Map for the above mod

Clarifier Modification

PRESIDENT GRANT AND MADISON

1)Cut d-52 and r-148.Find r-174 and solder a wire across the resistor.
2)Find the RED wire that comes off the clarifier control and cut it just before it connects to the PCB. Take that wire and solder it to GROUND on the PCB
3)Cut the orange wire just like the red wire but solder this wire to pin # 3 if IC-4 the MB3756 ic regulator.

This should give you about 5 khz is slide on this radio.

COBRA 148 GTL & UNIDEN GRANT XL

1) Cut R44 and D52.Find R174 and jump it .
2)Follow the red wire from the clarifier knob and cut it just before it connects to the PCB.Take this wire and solder it to Ground.
3)Find the orange wire from the clarifier and cut it the same.Then solder it to pin #3 of the mb3756 ic.

This should give you about 6khz of slide.

COBRA 2000 GTL

1) Cut R44 and D52.Find R174 and jump it .
2)Follow the YELLOW wire from the clarifier knob and cut it just before it connects to the PCB.Take this wire and solder it to Ground.
3)Find the RED wire from the clarifier and cut it the same.Then solder it to pin #3 of the mb3756 ic.
4)Cut the brown wire off the clarifier knob.



This should give you about 6khz of slide.The fine control will work also.

COBRA 140GTL,142GTL,PRESIDENT WASHINGTON,McKINLEY,AND P400



1)Cut r187 and d36
2)Find the red and orange wires commong off the clarifier knob.Cut them where they connect to the PCB.
3)Take the red wire and solder it to pin #3 of the mb3756 IC.Solder the orange wire to PCB ground.

NOTICE:On some radios the red and orange might have to be reversed to slide in the right direction.

10 Kc jump switch

Cut the trace going to pin #16 and bridge it with a 4.7k resistor. Then use a SPDT center off switch solder the middle terminal of the switch to the pin before the cut. Next solder one side to a 5 volt dc source and the side of the switch to ground or pin #18.

COBRA 142 AND 140GTL
MOD.-R104 AM PWR- VR6 SSB PWR-VR7
COBRA 2000 148GTL PRESIDENT WASHINGTON MADISON
MOD.-R131 AM PWR.-VR10 SSB. PWR-VR11

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