Sawtooth?
Eeewww.
Usually a mixer product problem.
Meaning, one signal combining with another - should result in a pretty clean match.
IF it's sawtooth - may be a combination of "minor glitches" making a mountain out of a Molehill...
In the effort, the Bennie schematic I got shows a TP203 and TR214 a twin Gate FET used as a combiner/Mixer amp using the main PCB's 9~10Mhz Xtal out and the PLL's own self-generated mess - to make a signal.
But to see sawtooth, can be 1 - a window for the mixer shuttering too soon, making a spike versus a pulse appear so the system attempts to "round" it into simple smooth sine wave, or the Bandpass Filter used to find and smooth out the signal this mixer makes - is off - considerably.
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To me? TR213 - the "doubler" and TR214 - are doing their job.
Tr215 is simply taking in what that BPF is finished working on - so this tells me one side is "stronger" than the other - the only way to know "which output" the Mixer TR214 is seeing - that is causing the sawtooth - you'll have to look at individually.
Start at TP203 - see what its' P-2-P is...
TP202 is so you can scope the output without loading the BPF.
But TR13...
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Has TP201...
I'd look at output ranges of value (power levels) and see if any of the cap- resistor combos are open especially in the feedback between Base to Emitter - generating a full-on high gain loop instead of controlled feedback.
And it's also not uncommon to see resistors like R256 R235 in their own setting - crack - being a dipped porcelain (think FLUSHING, NY) enameled body - that carbon composition body can easily crack as age weakens and eventually this "pencil lead of graphite" turns into another broken pencil...
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Excuse me Mrs. Johnson,
Can I have another sheet of paper to draw my family on?
Fortunately, or not - My Family Tree is the stick I use to draw with
