Note
QST, Aug 1971, p. 111.
Most of these were developed between 1969 and 1971.
MR-1: bundle includes MX-1, AA-1, VO-1, and TX-1.
AC-1: adds meter, antenna switch, knob and connector for MR-1.
AC-2: side-tone keying monitor
AC-6: converts PM-2 to PM-2B (adds 20 meters).
AC-7: converts PM-1, 2, and 3 to automatic semi-break-in,
AC-9: the electronic section of the Signalizer (S20).
AC-10: 400Hz filter and control.
KR-3: electronics section of the KR20 and KR5 keyers.
KR-5 electronics section of the KR40 keyer.
MX1: a syncrodyne detector converter (takes the place of an IF strip)
AA-1: audio amplifier
VO-1: oscillator-buffer
TX-1: crystal oscillator and amplifier