Total posts : 45366
From the sound of things, I’d venture a guess that your SSTRAN is exhibiting instability when the output tuning is just a little off. I had the same experience with mine.
To solve this problem, I swamped the output by installing a 5.6K resistor at R18 and a 560 pF capacitor at C23. This does waste a tiny bit of power, but it helps stabilize the output. My operating frequency is in the 1600-1700 kHz range. If your frequency is lower, you might have to tinker with the value of C23 a bit.