Radio transmits on freq just fine , in coming receive is off about 3 khz's ? Clarifier is nil and does nothing and it wasn't open on RX and TX to begin with.
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PC-122 OFF FREQ ON SSB RX ?
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in coming receive is off freq on both lsb and usb by about 3 khz , the transmit is on the money on freq on both as well as AM . its the incoming receive on SSB both sides. the clarifier is nil , does nothing , I even tested the clarifier and it is good , the problem is internal and adjustments are on freq as far transmit goes , it's just the incoming receive is off by 3 khz. I can't explain it any better then that.
That's easily said , but radio appears to be alighned on TX , The other question would be , Why the clarifier does nothing at all ? Transmits on freq , receives 3 khz off , even with clarifier center slot , it doesn't make any diff which way you turn it , it changes nothing ,It remains 3 khz off. Keeping in mind that it's NOT open on for TX to begin with.
If ? PLL is the problem , but yet it transmit is on Freq , if you go and alighn receive it will surely take TX off as bad as the RX was to begin with. Your saying it needs a PLL alighnment , by all means explain.
These perticular chassie's I have found to be strange over the years. they have always been heat boxes and don't care much for major tune ups (the less the best) , the receive on them is fair at best . Although a decent radio , not the best in my estamation. I can remember the in coming RX going out on one of these once upon a time ago. It surely turned out to be an exploratory surgery for given tech at the time , it wasn't that it wasn't receiving , it just wasn't showing up through speaker or ex.speaker. It turned out to be the biggest cap in the radio had went bad and was causing the problem .
By you saying it needs a PLL alighnment tells me little ? This thing is on freq on TX , AM receive isn't much of a problem although you have more room for error there concerning being on freq unlike SSB.
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Keep in mind that I haven't opened up a PC-122 in about 10 years...
It almost sounds like a crystal has gone bad, since the clarifier does nothing, I'd almost suspect X2 crystal, the 10.6975 crystal located above L19 and L20 could possibly be bad....it has to be something tied to the clarifier circuit in some form, doesn't sound like it's a PLL problem or an oscillator can being out of alignment.
If you have any extra crystals laying around, I'd replace both the 10.2417 crystal, and the 10.6975 crystal. I have a feeling these would fix the trouble.
What I have done in the past is use a 10.240 instead of the 10.2417 and just realign L15, L16, and L17. Replace the 10.6975 with same frequency crystal.
Make sure that all solder joints around the clarifier circuit are clean and solid, Bad solder joints can cause this problem also. The clarifier circuit area is around L15-L20, the 2 crystals I mentioned earlier, and VR3 which controls your TX frequency. Hope this gets you moving in the right direction.
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It almost sounds like a crystal has gone bad, since the clarifier does nothing, I'd almost suspect X2 crystal, the 10.6975 crystal located above L19 and L20 could possibly be bad....it has to be something tied to the clarifier circuit in some form, doesn't sound like it's a PLL problem or an oscillator can being out of alignment.
If you have any extra crystals laying around, I'd replace both the 10.2417 crystal, and the 10.6975 crystal. I have a feeling these would fix the trouble.
What I have done in the past is use a 10.240 instead of the 10.2417 and just realign L15, L16, and L17. Replace the 10.6975 with same frequency crystal.
Make sure that all solder joints around the clarifier circuit are clean and solid, Bad solder joints can cause this problem also. The clarifier circuit area is around L15-L20, the 2 crystals I mentioned earlier, and VR3 which controls your TX frequency. Hope this gets you moving in the right direction.
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Set for channel 20
Connect freq counter to TP3, located on left side of radio between L14 and L36. It is a bare resistor lead.
AM adjust L15 for 16.510 mhz +/- 20hz
USB set L16 for 16.5125 mhz +/- 20hz
LSB set L17 for 16.5075 mhz +/- 20hz
AM TX adjust VR3 for 16.510 mhz +/- 20hz
Connect counter to TP5, bare resistor located near IC3.
AM TX, set L18 for 10.695 mhz +/- 20hz
LSB TX set L20 for 10.6925 mhz +/- 20hz
USB TX set L19 for 10.6975 mhz +/- 20hz
Connect freq counter to TP3, located on left side of radio between L14 and L36. It is a bare resistor lead.
AM adjust L15 for 16.510 mhz +/- 20hz
USB set L16 for 16.5125 mhz +/- 20hz
LSB set L17 for 16.5075 mhz +/- 20hz
AM TX adjust VR3 for 16.510 mhz +/- 20hz
Connect counter to TP5, bare resistor located near IC3.
AM TX, set L18 for 10.695 mhz +/- 20hz
LSB TX set L20 for 10.6925 mhz +/- 20hz
USB TX set L19 for 10.6975 mhz +/- 20hz
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neither xtal can be suspected or tx would be off as well. so do not replace them.
it is something in the rx steering section of the clarifier. i would suspect a diode is not turning on like it should and allowing the rx voltage to flow thru the clarifier. it could be a bad solder connection or a faulty diode, or even another less obvious and less common component that has failed.
remember, the rx voltage bus feeds the clarifier. the clarifiers output voltage varies as you turn it. this change in voltage causes the 10.2417 xtals frequency to change, which shifts your rx freq. if there is no shifting voltage from the clarifier or very little voltage the 10.2417 xtal runs where it wants to run
i would check the legs of the clarifier. you should have a steady 8v on one leg, a steady 1.5v or so on another and the middle leg should vary as you turn the clarifier. if this checks fine, i'd then move to d24 and make sure there is volage on the both sides and that this voltage varies as you turn the clarifier.
it is something in the rx steering section of the clarifier. i would suspect a diode is not turning on like it should and allowing the rx voltage to flow thru the clarifier. it could be a bad solder connection or a faulty diode, or even another less obvious and less common component that has failed.
remember, the rx voltage bus feeds the clarifier. the clarifiers output voltage varies as you turn it. this change in voltage causes the 10.2417 xtals frequency to change, which shifts your rx freq. if there is no shifting voltage from the clarifier or very little voltage the 10.2417 xtal runs where it wants to run
i would check the legs of the clarifier. you should have a steady 8v on one leg, a steady 1.5v or so on another and the middle leg should vary as you turn the clarifier. if this checks fine, i'd then move to d24 and make sure there is volage on the both sides and that this voltage varies as you turn the clarifier.
Thank you for your time 8541 and others , about 7.5 volts and the 1.5 you spoke about on the clarifier , no voltage varience center leg of clar but none at d24 either side, I basically had already been there on the checking the clar part but d24 was new to me , although I changed it , still nothing. Any other suggestions ? It's just turning out to be a parts radio about now , I've had my ups and downs with PC-122s over the years , last one that meant anything to me cost while tech changed part after part for about an hour before he figured it out, I felt those minutes ticking like you wouldn't believe . I suppose it could have been worse. Appreciated the help here 8541. SK
you shouldn't need other suggestions. you found the problem yourself. lets look at this logically. if i could trouble shoot your radio without seeing it....then you should be able to pick it up from here.
you have 2 out of 3 of things i listed for the clarifier. you have the input voltage (7.5v), you have the reference voltage (1.5v), but you have no output voltage. so what do you think is the bad component?
just to let you know, if you have no voltage at the output of the clarifier then you'll have no voltage at d24. the clarifier feeds d24. so d24 is not your problem, whether you replaced it or not. if you would have had output voltage at the clarifier and at the unbanded side of d24 but not the banded side, then d24 would have been the faughty component.
oh and next time, giving information like, 'hey i checked the clarifer voltages and this is what i have.....', will help guys like me a lot. if you would have listed that in your first post, i could have told you right then what was faughty in the radio.
I said it twice in my prior posts that I checked the clar and it was good ...ooopps , I left out the voltage part , I did mean that. folks tend to think on different lines , especially when trying to spell it out like this. I Also said i appreciated your help 8541 , what more could I do other then that ?
I have no voltage at D24 on either side as I said . And to what you said Mole ,(It needs a PLL alignment) and I already stated my case about that. So I don't understand your comment in the least ? The bottom line here is , the radio is in front of me , I appreciated the help 8541 and it doesn't look like you have any further instructions. I wasn't exactly looking for
criticism here. Maybe I could send it to you Mole ? I see your now in the business of fixing radios ? Hmmm
i wasn't coming down on you, talking $hi! to you, or anything like that at all. and i was not asking for thanks, although i do appreciate that. i was only trying to steer you. you already found the problem, you just did/do no realize it.
if you do not have an output voltage from the clarifier, how can the clarifier be good?? the clarifier is bad. i was trying to give you some circuit theory to help you understand. i just thought you may like to find the problem yourself instead of someone telling you....sorry.
to make it easy and eliminate any confusion...... replace the clarifier and then re-align the pll circuit.
if you do not have an output voltage from the clarifier, how can the clarifier be good?? the clarifier is bad. i was trying to give you some circuit theory to help you understand. i just thought you may like to find the problem yourself instead of someone telling you....sorry.
to make it easy and eliminate any confusion...... replace the clarifier and then re-align the pll circuit.
I already changed the clar 8541 , same results. So it's obivious to me that there' s more to it then what "I've tried" so far to explain here , radio still does the same thing from the beginning , so it's something else in this perticular section of the radio that isn't kosher.
Thank you
"........move to d24 and make sure there is volage on the both sides and that this voltage varies as you turn the clarifier."