CTCSS Monitor (Inverted Logic)
For applications where the CTCSS monitor hookswitch circuit is open-circuit when the
microphone is on-hook, and closed-circuit when off hook (Ericsson-GE and others):
Remove R11
Install R20 (27K ohm)
Install R22 (27K ohm)
Install C17 (.001 uf)
Install Q3 (MPS2222)
If you ordered the 600L with this specification, this option has already been installed.
If an operating voltage (+8 to +12 VDC) not already available at microphone connector,
locate a spare or unused pin on the radio microphone connector. Some radio
microphone connectors may not have any obvious "spare" pins, but an existing function
such as speaker or handset receive audio may be disconnected to free up the pin.
Make a wire connection from this pin to a switched voltage within the radio (+8 to 12
VDC), and one that is filtered and/or regulated. Connect the microphone cable Blue
wire to this source voltage connector pin on the microphone connector plug.
If the radio application has no provision for providing the necessary operating voltage
for the microphone and the radio microphone audio circuit incorporates a bias voltage of
approximately 7 volts or more, a special version of the 600L is available from CES to
interface with this requirement. Contact your CES Sales Representative for more
information.
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