does anyone know how to open the clairfier to 10 + khz? i have the chip jump need the slide can any one please help me also i need the same for a galaxy 959 thanks in advance for any help
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Cobra 142 GTL
- Thread starter johne2hotty
- Start date
i want the clarifier to slide 10khz so i can get in between the channel the pll jump does not work the way i want it to does anyone know how to open this clarifier up to 10khz?? thanks in advance for any help
carl please dont take this the wrong way but can i have what i want? i dont like the pll jump thanks any how for your imput
If you open up the clarifier up that wide, it will be almost unusable. Unless you get/use a three turn pot on it - it will change frequencies far too fast to be using a standard pot. It will be too easy to be off frequency - even at 5kc! Even 1kc each way is almost too much for a stock pot.
The right way to do a 10kc clarifier is also having a fine/one-turn pot and coarse/five-turn pot adjustments.
That will work . . .
The right way to do a 10kc clarifier is also having a fine/one-turn pot and coarse/five-turn pot adjustments.
That will work . . .
Carl Im garthering hes not a SSB user thats why hes doing it the old way AM as we know will not let the receiving end hear the drift because AM is wide banded. I just ironically seen a friend go through this on a 142 out here he beat his head against the wall I told him I dont cut those clarifiers I center the transmit on frequency and let the clarifier do the receive as intended. Hes allover the place drifting like a yacht but AM is ok you cant hear it.
Ill look john Im sure I have what you are looking for in the piles of info I have if nobody chimes in with it.
Ill look john Im sure I have what you are looking for in the piles of info I have if nobody chimes in with it.
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im not trying to make anyone madd at me i just like the use of the clairifier ive been on the radio for 50 + years & i like to dial the clarifier in on them i got 3 each 148 Gtl,s & 3 uniden grants that have 10 + khz swing on them & they work just fine i just wanted the 142 to do the same thing the pll jump just dont work for me
First off - no one is mad at you!
Many of us have been thru this issue and are lending their experience.
What you want is up to you. But you may well regret it after all the work is done. It will be impractical. But you will find that out. People will tell you "you are off-frequency". Without a fine adjustment - you will never get it right with a 10kc slide. I talk SSB all of the time - either Ham and CB - and I can tell you that many don't want to talk to another station that is way off.
Just so you will know . . .
Many of us have been thru this issue and are lending their experience.
What you want is up to you. But you may well regret it after all the work is done. It will be impractical. But you will find that out. People will tell you "you are off-frequency". Without a fine adjustment - you will never get it right with a 10kc slide. I talk SSB all of the time - either Ham and CB - and I can tell you that many don't want to talk to another station that is way off.
Just so you will know . . .
Unfortunately, the Cobra 142's clarifier circuit isn't very "widebanded", and it's very difficult to mod it to get the 10+ kc of slide that you desire. The 142 uses a different board than the 148/Grant. One possible way to mod it would be to put a 5.6 uH choke in series with the varactor diode, that would achieve more slide, but your "center slot" would be around the 4 o'clock position to get the slide you want. You also sacrifice frequency stability as well, you'll drift like a sailboat. I know the +/- 10 kc switch mod isn't desirable for you, but it really is the best method to get the 10kc shifts on a 142.
Just my .02.
Cheers
Just my .02.
Cheers
Exit that is what I was saying aswell with this particular radio and a few others aswell. I was thinking he wasnt a SSB user so it would be ok for him 
I wasnt seeing anyone mad at him theres no reason why anyone would be its his radio and his choice what he wants to accomplish.
I think some people are thinking that if he was a SSB user that if it drifted that hhe would say that he was told to do it on the WWRF but most people that know this site know we are a legit bunch of radio operators Amateur /CB theres some really great advice and help here but in the end its the radio owners call on what he / she wants to do or again accomplish.
I will have to look through the older books and literature I have to see what I can find on this clarifier mod hes looking for.
I wasnt seeing anyone mad at him theres no reason why anyone would be its his radio and his choice what he wants to accomplish.I think some people are thinking that if he was a SSB user that if it drifted that hhe would say that he was told to do it on the WWRF but most people that know this site know we are a legit bunch of radio operators Amateur /CB theres some really great advice and help here but in the end its the radio owners call on what he / she wants to do or again accomplish.
I will have to look through the older books and literature I have to see what I can find on this clarifier mod hes looking for.
i thank any & all for there time & input its just my choice of the clarifier to be open i know the 8719 singal conversion is different than the dual conversion 8719 (148 gtl) but its what id like to do to it ive never had a bit of trouble to use my 148,s or my 2000 or grants on ssb they always worked great with no drift trouble i use a counter to dial it in & it stays right where i put it & all the radios were done well over 10 yrs ago now ive seen some of the new radios drift all over the place when just open 3 or 4 khz but im looking forward to you posting the mod. tony when you can im just an old guy (50+yrs) around the band just not use to the new stuff thanks john
i agree with the warnings others have posted about the touchiness of the clarifier once its expanded for 10+kz coverage, but i also believe its up to you to decide what to do to your radio, so, here is the clarifier mod for the 142GTL as i have it in my notes.
(wire colors may differ)
first, remove or cut D36 and R187. this disconnects the TX only voltage from the clarifier.
next, remove the red/white wire from where it connects the the PC board and connect it instead to pin 1 of IC5, the MB3756 voltage regulator. (pin 1 is toward the back of the radio)
if there is no red/white wire, you might have to trace the wires on the clarifier control back to the board.
there will be three terminals on the clarifier pot itself, one of the end terminals goes to an 8 volt receive only voltage source, and the other end terminal will go to PC board ground through a resistor. (R415, which might be mounted right to the clarifier pot)
the wire that goes to the 8 volt receive only voltage gets removed from the PC board and connected to pin 1 of the MB3756 regulator as mentioned earlier.
the wire that goes to ground gets left alone for now. you might end up messing with the value of R415 (3.3K ohms) in order to get some additional downward slide, but dont go below about 1k, as you could cause a power supply short with the clarifier knob in the extreme down position.
after you remove D36 and R187, and connect the clarifier pot to a constant 8 volt source (Pin 1 IC5) you will want to re-center the clarifier pot inside the radio.
set the clarifier knob right in the center of its movement, and set the radio on channel 19 USB mode.
connect a frequency counter to TP1 which is the lead of R184 that connects to L14.
adjust CT3 for 34.9875 mhz.
set the radio to AM mode and adjust L20 for 34.985 mhz.
set the radio to LSB mode and adjust L19 for 34.9825 mhz.
now you should be able to see how much upward and downward slide you have using your freq counter (you can just leave it connected the way it is and do the math eg: 34.985 - 7.8 (the IF) = 27.185 mhz)
if you think you need more downward slide, lower the value of R415.
if you think you need more upward slide, try putting a 5.6uH choke in series with the UNBANDED end of varactor diode D37. (this is the side that goes to ground)
you will find that your clarifier control is now pretty touchy and it may drift a bit on SSB making people hard to clarify.
the cure for this is to change out the clarifier pot for a 20K 10-turn pot.
you can get these from any NTE parts supplier or from mouser electronics.
you will have to drill out the knob a bit to get it to fit on the new pot. (use a 1/4" bit i think)
you will not get the amount of slide that you would with a 148GTL, as the large crystal they use in that chassis is the reason for the great amount of slide it can do.
good luck!
LC
(wire colors may differ)
first, remove or cut D36 and R187. this disconnects the TX only voltage from the clarifier.
next, remove the red/white wire from where it connects the the PC board and connect it instead to pin 1 of IC5, the MB3756 voltage regulator. (pin 1 is toward the back of the radio)
if there is no red/white wire, you might have to trace the wires on the clarifier control back to the board.
there will be three terminals on the clarifier pot itself, one of the end terminals goes to an 8 volt receive only voltage source, and the other end terminal will go to PC board ground through a resistor. (R415, which might be mounted right to the clarifier pot)
the wire that goes to the 8 volt receive only voltage gets removed from the PC board and connected to pin 1 of the MB3756 regulator as mentioned earlier.
the wire that goes to ground gets left alone for now. you might end up messing with the value of R415 (3.3K ohms) in order to get some additional downward slide, but dont go below about 1k, as you could cause a power supply short with the clarifier knob in the extreme down position.
after you remove D36 and R187, and connect the clarifier pot to a constant 8 volt source (Pin 1 IC5) you will want to re-center the clarifier pot inside the radio.
set the clarifier knob right in the center of its movement, and set the radio on channel 19 USB mode.
connect a frequency counter to TP1 which is the lead of R184 that connects to L14.
adjust CT3 for 34.9875 mhz.
set the radio to AM mode and adjust L20 for 34.985 mhz.
set the radio to LSB mode and adjust L19 for 34.9825 mhz.
now you should be able to see how much upward and downward slide you have using your freq counter (you can just leave it connected the way it is and do the math eg: 34.985 - 7.8 (the IF) = 27.185 mhz)
if you think you need more downward slide, lower the value of R415.
if you think you need more upward slide, try putting a 5.6uH choke in series with the UNBANDED end of varactor diode D37. (this is the side that goes to ground)
you will find that your clarifier control is now pretty touchy and it may drift a bit on SSB making people hard to clarify.
the cure for this is to change out the clarifier pot for a 20K 10-turn pot.
you can get these from any NTE parts supplier or from mouser electronics.
you will have to drill out the knob a bit to get it to fit on the new pot. (use a 1/4" bit i think)
you will not get the amount of slide that you would with a 148GTL, as the large crystal they use in that chassis is the reason for the great amount of slide it can do.
good luck!
LC
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