The few components required cost very little and can easily be assembled onto a
piece of “Veroboard”™ or similar. The complete assemby should be kept small. After
attaching wires, insulate it and tuck it away beneath the decoder board.
The sketch of the SRD400 front panel board, Fig.3, shows where to solder the three
wires. Zero volts is point “1”, Q152 collector is point “2” and IC151 pin 16 is point “3”.
The 12 volts is derived from point “4” on the small regulator board which is bolted
to the heatsink in the SRD400.
A minor drawback of the system is that the chosen segment will light while you are tun-
ing the receiver. To overcome this nuisance, disconnect the wire and switch the ADX ON
while tuning. Once the channels are tuned and stored, switch the ADX OFF, reconnect
the control wire, and it will then be switched on automatically for channels 40 to 48 only.
Page 10
Fig.3 Front Panel
Fig.2 Circuit