cOBRA 142 GTL EXTRA CHANNELS SWITCHES

[WR989_Dan]

OK I am totally lost on this one i got this radio and a road map seems to be wrong there are three switches on the back of radio and it seems the cb/pa switch also switches freqs to the road map says all three switches down is normal 40 but it is not whether the cb or pa switch is in either position was wondering if anyone knows how this mod works as i am lost seems like i get cvhannels 15 thru 40 with switches all down and cb/pa switch in cb sertting maybe this mod was done wrong? any help will be helpful

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[UnrealStunner]

Replace the 11.1125 mhz crystal with a 11.3258 crystal. Locate PLL MB8719 chip right behind the channel selector.

Isolate pin 10 from ground Cut all trace. Wire a switch from Pin 10 to ground and another from pin 11 to pin 12. You may need to re-align.


8719 channel chart Cobra 140 142 GTL

Position 1: Pin 10 down, 11-12 down

NORMAL CHANNELS

Position 2: Pin 10, Pin 11-12 down

15=26.815 20=26.885 25=26.925 30=26.985(ch3)
16=26.835 21=26.895 26=26.945 31=26.995(ch3A)
17=26.845 22=26.905 27=26.955 32=27.005(ch4)
18=26.855 23=26.935 28=26.965(ch1)
19=26.865 24=26.915 29=26.975(ch2)

Position 3: Pin 10 up, Pin 11-12 up

1=27.605 6=27.505 10=27.555 14=27.605
2=27.455 7=27.515 11=27.565 16=27.475
3=27.465 8=27.535 12=27.585 20=27.525
4=27.485 9=27.545 13=27.595 23=27.575
5=27.495

Position 4: Pin 10 down, Pin 11-12 up

1=27.605 11=27.725 21=27.855 31=27.955
2=27.615 12=27.745 22=27.865 32=27.965
3=27.625 13=27.755 23=27.895 33=27.975
4=27.645 14=27.765 24=27.875 34=27.985
5=27.655 15=27.775 25=27.885 35=27.995
6=27.665 16=27.795 26=27.905 36=28.005
7=27.675 17=27.805 27=27.915 37=28.015
8=27.695 18=27.815 28=27.925 38=28.025
9=27.705 19=27.825 29=27.935 39=28.035
10=27.715 20=27.845 30=27.945 40=28.045

 

[UnrealStunner]

Would be nice to see where them wires got hooked up.

The PA switch might be TB added to the radio.

 

[WR989_Dan]

ok ill get a pic of the wires

 

[Robb]

Replace the 11.1125 mhz crystal with a 11.3258 crystal. Locate PLL MB8719 chip right behind the channel selector.

Isolate pin 10 from ground Cut all trace. Wire a switch from Pin 10 to ground and another from pin 11 to pin 12. You may need to re-align.


8719 channel chart Cobra 140 142 GTL

Position 1: Pin 10 down, 11-12 down

NORMAL CHANNELS

Position 2: Pin 10, Pin 11-12 down

15=26.815 20=26.885 25=26.925 30=26.985(ch3)
16=26.835 21=26.895 26=26.945 31=26.995(ch3A)
17=26.845 22=26.905 27=26.955 32=27.005(ch4)
18=26.855 23=26.935 28=26.965(ch1)
19=26.865 24=26.915 29=26.975(ch2)

Position 3: Pin 10 up, Pin 11-12 up

1=27.605 6=27.505 10=27.555 14=27.605
2=27.455 7=27.515 11=27.565 16=27.475
3=27.465 8=27.535 12=27.585 20=27.525
4=27.485 9=27.545 13=27.595 23=27.575
5=27.495

Position 4: Pin 10 down, Pin 11-12 up

1=27.605 11=27.725 21=27.855 31=27.955
2=27.615 12=27.745 22=27.865 32=27.965
3=27.625 13=27.755 23=27.895 33=27.975
4=27.645 14=27.765 24=27.875 34=27.985
5=27.655 15=27.775 25=27.885 35=27.995
6=27.665 16=27.795 26=27.905 36=28.005
7=27.675 17=27.805 27=27.915 37=28.015
8=27.695 18=27.815 28=27.925 38=28.025
9=27.705 19=27.825 29=27.935 39=28.035
10=27.715 20=27.845 30=27.945 40=28.045

You will have noticed that there are only a FEW CB/regular 40 channels in there. That is what will happen if you change the xtal out for the other one. You don't have to; that is if you use the stock xtal you will have the regular 40 and a bunch of uppers too. So long as it has the MB 8719 PLL chip in it - that is. The other switch may be a 10kc switch.

I'm not certain of the info I put up here; but I'm pretty sure that someone that has done this mod will vouch for it. The Cobra 2000 is really an 148 GTL with some meters and a freq counter. Nice radio . . .

 

[WR989_Dan]

here are some more pics the best i could getnotice the 2 green wires from the cb/pa switch and were they got to

[/IMG][/IMG][/IMG]

 

[UnrealStunner]

Wow not sure whats going on there I can tell ya this there is more then whats is needed.

I can see the 1125 is still in use.

Can anyone chime in here?

 

[Robb]

Just noticed that it is a 142; not a 148 GTL. My mistake. The 142 board is like a late model Uniden Washington or a Prez Grant. But the info I posted above should be correct still . . .

The .1125 xtal shown in the pictures above looks like the stock xtal.

Since that is so; then the channels will be different from the ones mentioned above.
Maybe a close-by friend can help you out with the road map if he has a freq counter.

That 142 radio has the MB 8917 PLL chip in it already.

 

[WR989_Dan]

I believe there is a 10 kc switch but i dont know which one because i did some switching and the clarifier earlier had to be at 9 oclock now whatever i switched again the clarifier is at 12 oclock im guesssing the to white switches are for channels but still dont undertsand the cb/pa switch if im on channel 38 switch it to pa with all the switches down in the back channel 37 is then 38? weird

 

[UnrealStunner]

Just noticed that it is a 142; not a 148 GTL. My mistake. The 142 board is like a late model Uniden Washington or a Prez Grant. But the info I posted above should be correct still . . .

The xtal shown looks like the stock one.

Since that is so; then the channels will be different from the ones mentioned above.
Maybe a close-by friend can help you out with the road map if he has a freq counter.

Robb I always took the 1125 out and swapped on the 140 142 & I know the 148 you don't need to but I never seen the mod on the 142 like a 148 I might be wrong but again on the 140-142 I always done the swap.

898 Robb is correct bud you will need a counter or a friend with one or even another radio what has the xtras to listen to make your own map.

 

[Warbird]

Is there still a crystal on the component side of the board? Does one of those switches change between two crystals?