Hardware Hacking

Cobra 150 GTL CB Channel Modification

One of the easiest mods to do.  Next to the CPU is a surface mount resisitor R138, gently remove this to open the new channels.

Resulting frequencies ranges are 26.065 MHz  - 29.695 Mhz

1) Lift anode of D-30 and connect a 5.6 uH choke in series.
2) Cut D-32.
3) Cut both traces on the PCB going to the clarifier .
4) Solder one wire to PCB ground.
5) Solder a wire from the other cut trace to an 8 VDC source
(note: 8 volts can be found on the cathode of D-50)
6)This should give you 5 kc of slide.If more slide is wanted then change D-30 to a super slide doide.

1)Remove D-18 , R-110 , C131 and R-112.
2)Put jumper were R-110 was.
3)Take orange wire from delta tune and unsolder it from board then resolder it to Tr-23
(Solder to the pin closest to front of board.
It should have around 8 VDC on this pin.)
4)Put radio back together and if all is done right you should
slide transmit 5-6 KCs up and down.
For more slide change D-16 to a 1N-4007

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.

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