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Cobra 148 GTL Clarifier Unlock Question

P

Probate

Member
Feb 28, 2021
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Hi All,

I know i posted this question before but I really haven't seen a response to what I was looking for. Years ago I had a great tech unlock my clarifier with just a minimal amount of slide each way (less than a half channel). I prefer this because I talk on SSB all the time and easier to tune it in, just my preference. Does anyone know of a mod for this chassis that would achieve this?? Any input would be greatly appreciated.


Regards,

TY
 

remove D52.

Using a multimeter set to read continuity, with the radio off, put one lead on pin 6 of the MB3756 voltage regulator, and the other lead on either one of the outer lugs of the clarifier pot.
when you find the one that shows continuity to pin 6, follow it's wire to where it enters the PC board (probably right in front of R44).
pull this wire from that spot and solder it to pin 1 of the MB3756 voltage regulator.

now using a known accurate frequency counter connected to TP1, adjust L22, L23, and CT2 for the proper frequencies according to the service manual.

that's it!
LC
 
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loosecannon said:
remove D52.

Using a multimeter set to read continuity, with the radio off, put one lead on pin 6 of the MB3756 voltage regulator, and the other lead on either one of the outer lugs of the clarifier pot.
when you find the one that shows continuity to pin 6, follow it's wire to where it enters the PC board (probably right in front of R44).
pull this wire from that spot and solder it to pin 1 of the MB3756 voltage regulator.

now using a known accurate frequency counter connected to TP1, adjust L22, L23, and CT2 for the proper frequencies according to the service manual.

that's it!
LC
Click to expand...

Thanks for the post, worked great!!!

Have a great night!
 
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Probate said:
Since you're on a roll, is there a mosfet conversion for a cobra 148 gtl out there that you recommend?

Regards
Click to expand...
For me personally, I wouldn't do it unless the final takes a dump on you. If you want more power, just run the radio with an amp. A 148 is great for a 2 pill or a 5 pill.
 
999 said:
For me personally, I wouldn't do it unless the final takes a dump on you. If you want more power, just run the radio with an amp. A 148 is great for a 2 pill or a 5 pill.
Click to expand...
final is bad, just want to try it, I have a few of them
 
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here ya go:

MOSFET conversions for upD858 and MB8719 boards

After doing some research, and a lot of testing, I have successfully done conversions on the upD858 AM/SSB and MB8179 AM/SSB chassis. For these conversions, I used IRF520N's from International Rectifier. I'm sure you could substitute ERF2030's if you wanted to do so. For the upD858 chassis...
www.worldwidedx.com www.worldwidedx.com

For the record i have not done these mods myself, but i can vouch for Exit13's knowledge and experience.
he is a very talented technician.

be sure to read through the whole thread in case there are updates or typos that have been addressed.
LC
 
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loosecannon said:
here ya go:

MOSFET conversions for upD858 and MB8719 boards

After doing some research, and a lot of testing, I have successfully done conversions on the upD858 AM/SSB and MB8179 AM/SSB chassis. For these conversions, I used IRF520N's from International Rectifier. I'm sure you could substitute ERF2030's if you wanted to do so. For the upD858 chassis...
www.worldwidedx.com www.worldwidedx.com

For the record i have not done these mods myself, but i can vouch for Exit13's knowledge and experience.
he is a very talented technician.

be sure to read through the whole thread in case there are updates or typos that have been addressed.
LC
Click to expand...
Thanks Again for the quick reply
 
loosecannon said:
here ya go:

MOSFET conversions for upD858 and MB8719 boards

After doing some research, and a lot of testing, I have successfully done conversions on the upD858 AM/SSB and MB8179 AM/SSB chassis. For these conversions, I used IRF520N's from International Rectifier. I'm sure you could substitute ERF2030's if you wanted to do so. For the upD858 chassis...
www.worldwidedx.com www.worldwidedx.com

For the record i have not done these mods myself, but i can vouch for Exit13's knowledge and experience.
he is a very talented technician.

be sure to read through the whole thread in case there are updates or typos that have been addressed.
LC
Click to expand...
i noticed these transistors are hard to come by, any other alternatives or resources?
 

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