Howdy all.....Looking for a schematic (or a link to) for this small,
tone encoder/decoder which appears (by it's construction) to may be
from the 60's or early 70's. The Johnson part number stencilled on the
rear apron is 250-861-100. The unit is a small gray box 4" x 1.5" x 6"
(WxHxD) with a single spring lever switch on the front marked CALL -
OPER - STBY (spring loaded in the call position) along with a large red
lamp.
The rear apron has a multi-wire cable with an 11 pin round female socket
(Amphenol PF11 style) and a stamping 13.8vdc 2watts. The unit I have is
in perfect condition and reminds me of the old Johnson Messenger series
27 - 30 Mhz radio's which may have had a corresponding male connector
(with a shorting plug) on them. The frequency determining element
inside appears to be a resonant reed relay. Any info appreciated.

73 - Gord VE1AJF