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My FT-980 is series 04. So I guess all service notes needed in early versions were done.

After fixing the PA, next day I found that LSB reception was... strange, like added AC, tremolo when listening CW in LSB mode... in short very bad. All other modes were OK as much as I remember. After some 10 minutes LSB reception was normal, and I made a one hour QSO with very good reports on my modulation, I received all OMs with no problems. But the problem is there. Only in LSB and only the first 10 minutes.

I read about and thought about TC01 in PLL unit. A well known candidate. So I checked as per service instructions. USB, Witdh CCW, and no voltage at all. Whatever I do cero voltage in TP. The radio was receiving OK in USB, but still horrible sound in LSB. I was sure I was doing something wrong, and check and check and changed meters, they show 0,00V.

Until it got warm. And LSB sound became normal. Not a believer, I rechecked voltage in TP, and I had voltage, but out of range. USB and WIDTH CCW about 3V. LSB and WIDTH CW 1.5V. Exactly half what the manual says (6V-3V/4V)I hope my meter is OK. That is why I opened a new thread, works after 10 minutes and voltage ratio USB/LSB 2:1 is almost exact. Just it does not exist in cold and when appears is half the normal value.

As I told in the PA problem thread this radio has been sleeping for more than 25 years. And as today I have not realigned anything. So I guess I should do something with my limited means.?

BTW I hope the large metal cover of PLL/VCO units lifts just pulling. I dont have good test equipment, but I have a frequency meter, good ceramic trimming screwdrivers, and a RF probe I have never used. And null experience in PLL or similar.

Neither the user manual nor the service, explains the signal path or function. In my old FT-101ZD the operation manual described with detail how the radio worked.

Well, if I wait 10 minutes before I use it in LSB it is a nice radio. But I would like to understand what is happening.

73 EA1FC

I read the service manual, I say I look at the schematics, and found the trimmer. As I said i have no idea about PLL but inside the can there is a transistor with a thermistor in the emisor in parallel with a resistor. And my problem disappears when radio is hot.

So I decided to accelerate the process. Took a soft hair drier and pointed to the holes for TP and TC. And the "time to normality" went almost to zero.

So I guess the no voltage in TP and strange sound in LSB has to do with this transistor not oscillating, or something similar, as I said I have no idea about PLL neither this transistor that does not look as a transistor in the schematic hahahaha

The service manual says to avoid touching the trimer capacitor until 5 minutes from cold start, coming from 1h cold 15/25?C. After some minutes I get voltages, but 50% what the manual says. around 3V in USB, 1,5V LSB, Witdh according to manual.

I dont know what is going on. Supposing this "malfunction" is not normal, I guess it will be due to low voltage somewhere so the Thermistor takes a longer time to reduce resistance. I helped with the hair drier. I did not want to put too much hot air through the holes as my grand dad told me too much heat is not good for semiconductors.

I glued the 2nd FI FT 455kHz filter in the metal cover of PLL unit, and wired it to FI unit. So it is not so easy to lift the cover.

I guess this large cover just pulls up, held by some presure in the sides. I may try.

In the meantime I go on thinking next step. I think it will be? a problem of voltage, a bad resistor or capacitor.

Maybe I manage to catch a friend that says he knows about PLL.

73 EA1FC

Finally my FT-980 is more or less OK, the only strange thing is temporal. LSB beat is wavering, I guess the PLL is not locked, manual tells to wait 5 minutes before adjustment and in my case is around 10 minutes. And voltages are low.

I managed to adjust the 30MHZ to 4Hz error, and now all is close to perfect. Display exactly on frequency and listening to AM broadcast in SSB, voice? tone or music does not change when I change LSB and USB. As I have a 2.1kHz wide filter in 455 FI, if it is OK, it means it is almost perfect.

The only repair after a long seach, and besides adjustment, has been the tantalum capacitor in PA Q01 collector, 10uF/25V it was shorted pulling TX13.5V to 3V and activating the overload of the 13.5V PS. It had the mod to feed PA Q01 from TX13.5V instead from general 13.5V

Regarding PS heat, I feed the radio with 200V, with input wired for 234V, and voltages seem to be OK, reports are of excellent modulation, and fan never comes in in RX

I had a look at my FT-ONE with a similar PA and all seem to be OK. Tantalum in PA Q01 collector is 10uF/16V. I note that the only tantalum catastrofic in these PA that I have met have been of the 25V type, in short ALL I have seen, while none of the other 10uF/16V have been damaged, and that counts about 20 times more. So without any real reason I would recomment check the FT-980 radios and similar, and change PA Q01 collector tantalum capacitor in case it is of the 25V type. It sounds silly but maybe the 16V capacitors (all brown color) are more reliable than the 25V (blue or red in what I have seen)

I think FT-707, 107, 980 and ONE have a very similar PA.