Cobra 142GTL Variable Key Help

[mattsowders1989]

Hello all,
I'm new here. I am on CBjunkies.com quite a bit and heard about this site through that forum. I'm needing help with installing a variable key in the above mentioned radio. I've built the mod (I've built many), I've just never put it in a 142GTL. I can't find info anywhere on where to put it. The best I can find is to cut VR6 and put it there. Problem with that is i need to tap a coil somewhere for the 3rd pot wire (one wire goes to the cap/transistor, one goes to a ground and resistor, one goes to a coil). I just want to find the best way to incorporate this variable key. It's a pain to open up the radio every time to adjust every thing just to get the desired dead key with the right amount of swing. Thanks for any help!

73's from 677 Central KY

 

[222DBFL]

Hey Matt you made it here!! Good deal!! Also look around the forum with the search function, you might find the mod that way.
To All, I recommended him to come her guys. Please someone help this guy out. He is good people!! Thanks for any responses!!! Good day!!

 

[mattsowders1989]

Thank you Sean!!!

 

[sonoma]

the way I am reading what you wrote down sounds like you have built a setup like used in a cobra 29 using a tip120 trans.you are talking about 3 wires and a coil which is what is used for the variable on the am only radios. the only way I have ever done a 142 radio is put a pot external for VR6 to adjust it up and down. it takes 3 wires. one to the ground of the vr6, one to the plus side of the wiper and one to the neg side of the wiper. should have said clockwise and counter clock wise on the wiper.
has been years since I put a variable in the cobra 142. I normally just do what some people call a npc mod. it drops the dead key to 2 watts with full swing on AM. do not have to mess with a variable this way.
each his own idea.

 

[mattsowders1989]

ok. i understand. the only problem i see with using vr6 externally is that when the output power goes so low, there is barely any swing. my best guess is that it just is what it is. what resistance pot should i use if i do put vr6 external?

 

[sonoma]

you can try a 5K in it. if you did the npc mod you would not have to worry about a low swing as you mentioned when you turn the power down.

 

[mattsowders1989]

oh ok. Thanks so much for the info. i greatly appreciate it!!!

 

[mattsowders1989]

by the way, i dont use the tip120 transistor. i use something a little different

 

[Robb]

Yeah? What did you use that was different?

 

[mattsowders1989]

i use a tip29 transistor with a 470uf cap instead of the tip120 mod

 

[Robb]

Same difference.
Ever try a 1000uf cap?

 

[mattsowders1989]

no. Have you?

 

[Robb]

Yuuup . . .
But not on the 142; the 29's.

 

[sonoma]

here is the best variable for your radio. it covers all the 385 board radios. I had to search all my files to finally find it.

 

[LeapFrog]

Same difference.
Ever try a 1000uf cap?

I didn't notice a difference over 220uF have you?