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NPC-RC for Cobra 148

  • Thread starter Thread starter cbdoctor
  • Start date Start date
C

cbdoctor

Guest
This is my NPC-RC Conversion for the Cobra 148.



It will also work for the

Uniden Grant but you will have to interpret it as far as part numbers goes.



Remove the AM/Regulator feed wire for the final from TP-7 and solder it to

the Cathode of D-55



Do not remove any transistors as it looks shoddy! (personal opinion)

Instead, remove R-131.



Change C-174 to a 10 mFd. Located by the AM/Regulator.



Remove R-194 and save. Located real close to C-174.



Replace it with a 100-Ohm 1/4-Watt resistor.



Replace R-196 with the 1K that you saved from R-194 removal.



Adjust the driver bias to 50 mA. (Power up the radio, put it

in LSB or USB, set the mic gain at minimum, remove the wire

from test point 8, insert a milliamp meter in series between

the test point (which is positive) and the wire, key the mic,

and adjust bias adjust pot until the meter reads 50 mA.)



This is a "preset"



After adjusting the final bias in the next step and While observing the

modulation envelope on the scope, come back to the driver bias adjustment

and adjust it for best negative peak compression--the point that the

compression forms the most rounded shape for the negative peak while

modulating the unit to the maximum positive peaks without clipping.



Adjust the final bias to 100 mA. (Same instructions as in preceeding step

except the test point is test point 7.)



Adjust the carrier for 2 Watts.



This completes the NPC-RC Conversion and will give results similar to the

Galaxy NPC-RC Conversion.






<font color="#ffcc66">
Billy Dean Ward

</p>
smallmod.gif


</p>AKA The C. B. Doctor</p>
 

This is my NPC-RC Conversion for the Cobra 148.



It will also work for the

Uniden Grant but you will have to interpret it as far as part numbers goes.



Remove the AM/Regulator feed wire for the final from TP-7 and solder it to

the Cathode of D-55



Do not remove any transistors as it looks shoddy! (personal opinion)

Instead, remove R-131.



Change C-174 to a 10 mFd. Located by the AM/Regulator.



Remove R-194 and save. Located real close to C-174.



Replace it with a 100-Ohm 1/4-Watt resistor.



Replace R-196 with the 1K that you saved from R-194 removal.



Adjust the driver bias to 50 mA. (Power up the radio, put it

in LSB or USB, set the mic gain at minimum, remove the wire

from test point 8, insert a milliamp meter in series between

the test point (which is positive) and the wire, key the mic,

and adjust bias adjust pot until the meter reads 50 mA.)



This is a "preset"



After adjusting the final bias in the next step and While observing the

modulation envelope on the scope, come back to the driver bias adjustment

and adjust it for best negative peak compression--the point that the

compression forms the most rounded shape for the negative peak while

modulating the unit to the maximum positive peaks without clipping.



Adjust the final bias to 100 mA. (Same instructions as in preceeding step

except the test point is test point 7.)



Adjust the carrier for 2 Watts.



This completes the NPC-RC Conversion and will give results similar to the

Galaxy NPC-RC Conversion.






<font color="#ffcc66">
Billy Dean Ward

</p>
smallmod.gif


</p>AKA The C. B. Doctor</p>
 
Well, with all do respect to you CB Doctor, I'll wait until I'm back in your neck of the woods.....I'll let a professional do the work! I have a Grant XL and I think this is the mod for it! I've been down by your shop a couple of times within the last two weeks, but to no avail...no one was home. Must be 'banker's hours'. I should be back around your way soon, I hope I can 'catch' you when you're in.....I WANT THIS MOD IN MY GRANT XL!!! I'll talk to you about a few other things when I see you Billy........

73s


-Bucbuck-</p>
 
Well, with all do respect to you CB Doctor, I'll wait until I'm back in your neck of the woods.....I'll let a professional do the work! I have a Grant XL and I think this is the mod for it! I've been down by your shop a couple of times within the last two weeks, but to no avail...no one was home. Must be 'banker's hours'. I should be back around your way soon, I hope I can 'catch' you when you're in.....I WANT THIS MOD IN MY GRANT XL!!! I'll talk to you about a few other things when I see you Billy........

73s


-Bucbuck-</p>
 
I think the ol' Doc is lost y'all!!! Look at how old this post is??

Good to see ya back here Marconi;it's been awhile sir!

I sure hope all is fine your way! Slim CDX285


slimsig.gif
</p>
 
I think the ol' Doc is lost y'all!!! Look at how old this post is??

Good to see ya back here Marconi;it's been awhile sir!

I sure hope all is fine your way! Slim CDX285


slimsig.gif
</p>
 
Marconi

I remember It was Big Mike. The test was funny also ( all True) . He and Biil Eitner are knowhere to be found, I wonder whats up with that.



I got to tell you all they did put out some great info.



Tim



Rfmatrix


</p>
 
Marconi

I remember It was Big Mike. The test was funny also ( all True) . He and Biil Eitner are knowhere to be found, I wonder whats up with that.



I got to tell you all they did put out some great info.



Tim



Rfmatrix


</p>
 
I'm in the middle of trying this mod and I don't understand step one. Do I remove the cathode end of D-55 from the board than solder the wire to it or solder the wire with the end still in the board?
 

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