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Where does the ground of the audio path go in this schematic?

Schematic

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    $\begingroup$ to the 0 V rail of the PSU. And yes, it should be built in an shielded enclosure, which also connects to the 0 V rail. This enclosure can then be grounded to station ground. (IMHO) $\endgroup$ – Edwin van Mierlo Feb 21 at 8:42
  • $\begingroup$ Ground symbols can be tricky, but I'd always interpret that symbol as "chassis ground". That would suggest all ground references in the modulator are connected to the chassis, which is almost always connected to earth ground. It's not shown, but I wonder if the chassis is connected to a transformer secondary centre tap? This would allow the audio to move above and below ground. $\endgroup$ – Buck8pe Feb 21 at 10:16
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    $\begingroup$ @EdwinvanMierlo Please post an answer as an answer, not a comment! This keeps things organized and makes sure the question doesn't look unanswered to the system. $\endgroup$ – Kevin Reid AG6YO Feb 21 at 15:15
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If the schematic doesn't show a separate audio signal ground, then the audio input ground is clearly meant to be connected to chassis ground. The power supply ground is also not shown, which means that it too should be tied to chassis ground. All the ground symbols in the schematic are chassis ground, rather than earth ground.

Since the circuit is an RF circuit, you should probably build it in a shielded enclosure (aka chassis), which would be the chassis ground. The RF input and output connectors should be RF coaxial connectors, grounded to the chassis of course. The enclosure should be connected to the station ground.

(A comment with essentially the same information as this answer was posted several days before. This answer was posted mainly so that the question officially has an answer, in the hope that the question won't keep popping up again and again on the "home" page.)

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