In my youth, end of the 70ies, it was my dream to have such a radio. Today I know that it is one of the worst radios that existed. I love it now, to have one 🙂
I looked a very long time for one of that radios. I wished me a TS-788DXcc, but this one the TS-780DX is harder to get as the TS-788DX. I had the luck that in the Ham Radio exhibition, one was sales. I got it for 100€.
The mike was strong modified with a lot of holes in and broken. So I throw it away.
Its seem to be not possible to get one of the “service manuals” with alignment instructions.
So I find out all alignment points by my self in the circuit layout.
The TS-780DX can not use FM with modern radios together! Its an very old FM standard
what use the 1.5 KHz filter from SSB. That does not working very well.
FM frequency deviation, 1.5KHz. That’s the max what this filter can handle
If you adjust more, the the FM Mod is strong disturb.
FM modulation clearness. They are still spikes on the sine. And so it sounds.
But it works not better, without a big modification.
You can try to get the FM receiving clearer with the FM filter (see upper side alignment pictures at the left side).
The Frequency is drifting with the temperature of this radio very high. I measure a difference from 700 Hz! So you can try to get it better. But with the temperature in your room, the frequency is changing. We have in Germany a proverb: “Sie läuft wie ein Feldhase” Translation “It runs like a hare” 🙂
AM/FM Frequency, that 10 Hz to high. very good
If I get the right color, I will paint the case new with Sommerkamp blue.