858 PLL FREQ MOD

[858 pll chip]

COBRA 138 139 XLR (OLD) PRESIDENT GRANT, WASINGTON,MADISON , ROYBN 510 , 520D ,TRC-449 457 AND 458

1)FIND PIN #19 OF THE 858 CHIP.THIS PIN WILL BE CONNECTED TO GROUND WITH A SMALL TRACE. CUT THE TRACE AND SOLDER A 4.7K OHM RESISTOR ACROSS THE CUT .

2)FIND PIN#21 AND DO THE SAME AS YOU DID TO PIN #19.

3)INSTALL A SPDT/CENTER OFF TYPE AND ALSO A SPST SWITCH IN THE CHASSIS OF THE RADIO.SOLDER THE WIRE FROM THE CHIP TO THE 2 SWITCHES AS IN THE PIC ABOVE.

4) TURN THE RADIO ON AND SEE IF ALL THE CHANNELS WORK.IF NOT THE YOU WILL NEED TO "BRAOD BAND" THE RADIO.CUT THE 2 TRACES AND INSTALL THE 2 JUMPERS AS IN THE PIC BELOW.

Now with s1 up and s2 center this is the reg CB
With s1 up and s2 up will be 27.455 to 27.805 on CH. 8-40
With s1 up and s2 dn will be 27.855 to 28.005 on CH.8-20
With s1 dn and s2 up will be 26.455 to 26.805 on CH. 8-40
With s1 dn and s2 dn will be 26.855 to 26.955 on CH.8-16
With s2 dn and s2 center will be 26.085 to 26.45 on CH. 11-40

Broad Band Alignment

[broad band mod]


Unlocking the Clarifier

1)Cut R-117
2)Cut D-30
3)Find the backside of the clarifier knob.Follow the PURPLE and BROWN wires and cut them just before they connect to the PCB.
4)Solder the PURPLE wire to an 8 VDC source.
5)Solder the BROWN wire to GROUND.

[mm CB shop]

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