||Type 685 Transmitter 7AL AP W7943A
||CDK [Receiver P40] AP W7945A
||Type 685 Transmitter 7AL AP W7943A and
Conversion Kit AP 58250
||CDQ [Receiver P40] AP 56187A
It is used on vehicles and other craft as the main or
supplementary equipment. It may be installed with or without remote control
and may be set up for SIMPLEX or DUPLEX working.
It is crystal controlled and operates [TX and RX] on pre-determined spot
There are 3 separate chassis for the power supplies plus an additional
power supply mounted on the speech amplifier chassis which give the LT and
the speech amplifier supplies.
Power output was 100 Watts.
A station set up to use Type 685 and outfit CDK or Type 685 +
Conversion Kit and
outfit CDQ, requires, in addition, one or more of the aerial outfits AGU,
AGY, AGW, AGP or AGO, which are supplied separately, and one or more of the
- Control Outfit KSC - for simplex working only.
- Control Outfit KSD - for duplex working with NO LINKING outfit
- Control Outfit KSF - for duplex working WITH a LINKING unit
employed - this outfit is required where the AUDIO input and output are
to be extended for other purposes e.g. connection with a field telephone
exchange or relaying through another circuit.
- Aerial Switching Unit Outfit ESC - for simplex working only.
In its time  this set can either be thought of as 'simple' or
'very sophisticated', the latter having every conceivable device option
fitted to the Type 685. The FACILITIES available were as follows:-
||Available with either local or remote positions. In
both instances HT switching of the transmitter is carried out by
means of the pressel switch in the handset.
||Operation is available with either local or remote positions.
HT switching of the transmitter is or is not possible at the handset
according to the outfit used. With duplex operation, the radio
station can be connected to a field telephone exchange so that any
extension of this exchange can speak over the radio link.
||Teleprinter operations of a duplex link is possible. This
requires a teleprinter, teleprinter terminal unit, teleprinter
rectifier unit and an S + DX MkII in addition to the outfits
||Where 2 complete installations are fitted in close proximity
to one another, as in Radio Van 19A, the installation may be linked
together so that what one station receives can be re-radiated
on the other circuit and vice versa.
Click on this file to see the full Duplex Linking System
685 DUPLEX LINKING.pdf
This to see the unit wiring and connections for the system
685 unit wiring.pdf
685 radio relay rack with cover lowered.