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Help with 148 gtl Clarifier Mod

Z

zerocool5878

Member
Mar 28, 2013
4
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I am trying to understand this. I would like to have 6khz up and 6khz down with the center being right in the middle.

I found this online
1. Find D52, R44 and R174 and remove them.
2. Solder a jumper from where you removed R174
3. Follow the WHITE WIRE from the clarifier control to where it attatches to the PC board and UNSOLDER it.
4. Resolder this WHITE WIRE to the PC board ground.
5. Follow the ORANGE WIRE from the clarifier control to where it attatches to the PC board and UNSOLDER it.
6. Resolder this ORANGE WIRE to pin 3 of MB3756 Regulator.
you should slide about 4Khz down and 1Khz up.

-----------------------------

If you do the changes below you will get -6khz to +6hhz with 0 right in the middle. The Tx will track exactly with the Rx
1. Jumper R175
2. Jumper D51
3. Remove R149
4. Remove R188
5. Remove R44
6. remove wire form the high side (+ or full clockwise pos) of the clarifier
7. conncect pin3 of the IC4 to the high side of the clarifier
8- Replace R174 with a 3.3k resistor
9. Attach a 12k resistor from the jumper of D51 to pin 3 of IC4

So I have some questions here
First is the second set of instructions an add on to the first instructions or is the second a replacement for the first instructions? At first I thought it was its own stand alone instructions but the second one does not require doing anything to D52 and would also only be changing one wire on the knob.

Also in regards to step 6 my knob colors are orange blue white. I am pretty sure that the white is what is considered the high side but I want to make sure.


Any help would be greatly appreciated.
 

Looks like I put this into the wrong section. Sorry about that. Could a moderator please move it to the appropriate section? Thanks
 
I would say unless you have the proper equipment and know how to do a mod like that I would send it to a skilled tech. This way the whole radio can be checked over, receive alignment, frequency alignment, and proper dead key and PEP wattage. Reason I say this is once you do this mod the radio will need to be checked to make sure both transmit and receive are aligned together.
 
@9C1Driver I already have an oscilloscope and a frequency counter. I have just bought a watt/SWR meter and dummy load that should be here next week. I have been tinkering with electronics for the last 15 years. I have failed plenty of times. I would like to learn how to do these things myself. I would rather just throw the radio in the trash and take it as a learning experience then to send it to someone and learn nothing. I appreciate that you are just trying to save me from headaches but I will not learn anything without them.
 
Hi, if your radio has the MB3756, pin 1 is the correct pin. The modification that involve pin 3 pin (mirror), is more than a decade old and is wrong. Instead of installing a jumper (R174), use a low value resistor. Some people replace the varicap with NTE612, NTE614 or M-65 Super diode or simply add an inductor 4.7uH in series.

Greetings from the Caribbean

<gotproof>
 
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you also need to know which radio version you have. if it is the very last radios with the front mic plug more than likely it has 5 volts at the PLL and not the 8 volts as listed. you open the clarifier at 8 volts as stated you will knock out the PLL
 
Thanks yea this is a 94 Philippines side mic. Im going to try just doing the second set of instructions but using pin 1 instead of pin 3 and see how that goes.
 
zerocool5878 said:
@9C1Driver I already have an oscilloscope and a frequency counter. I have just bought a watt/SWR meter and dummy load that should be here next week. I have been tinkering with electronics for the last 15 years. I have failed plenty of times. I would like to learn how to do these things myself. I would rather just throw the radio in the trash and take it as a learning experience then to send it to someone and learn nothing. I appreciate that you are just trying to save me from headaches but I will not learn anything without them.
Click to expand...


I understand what you say and where you are coming from. You are that 2 in 10 that actually have some repair gear and are trying to learn.
 
after you open the clarifier you will have to realign the radio since it will throw it off some. just for your info.
 
sonoma said:
after you open the clarifier you will have to realign the radio since it will throw it off some. just for your info.
Click to expand...


Hey hey now come on, this guy knows what he is doing as he stated. he has no time for comments from guys like you or me.
 

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