How and where to put Variable power in a 139 XLR

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COONHUNTIN' COBRA FAN
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Location: Mount Hermon, KY

How and where to put Variable power in a 139 XLR

Post by COONHUNTIN' COBRA FAN »

I used to make a variable power mod on some of the Cobra and Uniden mobile radios using a transistor (rat shack part #TIP 120), a resistor, the RF gain knob or other comparible pot. Installation was pretty close to the same in them all!

I would like to do the same or a similar mod to my 139XLR....
does anyone have any ideas?

Also, if you know of any variable power and or super mod ideas for a
Uniden Grant... the old one with the MB8719 PLL... you can post it here as well! I have one of those I'm going to play with when I'm done with my 139XLR!
johhn
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Location: East Texas - 361

re;power

Post by johhn »

Well the a.m power VR pot is where you usily put or pull out , for the wires for the gain (power) veribal vr-8.
johhn
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Joined: Wednesday 14th Nov 2007, 1:35
Location: East Texas - 361

re;v power

Post by johhn »

Do the modulation swing first ,
adjust vr-6 , and vr-7 for the most modulation swing
Forward on a meter you can get... :P
COONHUNTIN' COBRA FAN
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Joined: Thursday 15th May 2008, 3:01
Location: Mount Hermon, KY

THANKS

Post by COONHUNTIN' COBRA FAN »

Thanks for the help! I already figured it out for the Grant and the 139xlr..

I now have 1/2 watt to 8 watt dead key on the Grant with swing up to 25

and 1/2 watt to 7 watt dead key on the 139xlr with swing up to 20 watts!!

The way I make the variable super mod with the rat shack TIP120 and a 100uf cap and a 100 ohm resistor and a variable pot such as the RF gain knob I end up with an input wire and an ouput wire! I wound up tracing the output path of the audio output to the collecter of the driver and tied into it! It works much like the way I installed it in the old Cobra AM mobiles!!!
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