The capacitor that we add to in parallel for a lower-pitch tone appears unmolested. This one should have a fairly high-pitched single beep.
Whoever installed it didn't know how to shut off the beep in a civilized way. The instruction sheet says to put a switch in line with the audio wire. This gets you a "roger pause". Shuts off the beep, but not the unkey delay.
Seen in the second pic there is a diode at the far left center of the board with its long lead on the outer edge. You pull out the long lead of this diode from the board. Put one end of a wire in the hole it came out of, other end to the switch. The other switch wire gets one end lap-soldered to the loose end of the diode, other wire leading to the off switch. Shutting off this diode turns off the unkey delay.
And the beep.
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