1402MAN.TXT
ADDITION TERMINALS for Model 1402D
RELAY CONTACTS (TB1-9, 10, 11); (TB1-12, 13, 14):
These six terminals comprise two sets of SPDT relay contacts.
The relay contacts close and remain closed for the entire
duration of the identification period. One set of contacts may
be used to key the transmitter and the other set may be used to
connect audio into the transmitter microphone circuit.
These relay contacts break down as follows:
TB1-9
N. C.
TB1-12
N. C.
TB1-10
Common pole
TB1-13
Common pole
TB1-11
N. O.
TB1-14
N. O.
AUDIO OUTPUT (TB1-7 and TB1-8):
This audio output is transformer-coupled, DC blocked and
electrically isolated from the chassis. Approximately 100 volts
may be placed across these terminals without damage. The output
is a sine-wave 600 OHM impedance and its output is variable with
R28.
AUDIO MONITOR (TB1-15 and TB1-16):
The audio monitor is designed to connect directly across the
receiver's volume control terminals (high side and ground) or to
a standard 600 OHM audio transmission line.* Its 10K OHM input
impedance allows for relatively minimal audio power losses. The
function of the audio monitor is to keep a watch on receiver
activity and to prevent the identifier from keying the
transmitter until the channel is clear. Its function is much
like that of the COR monitor terminal except that it is audio-
controlled instead of DC-controlled.
The audio monitor needs about 40mVAC to trigger, which is
considerably less than what is normally found on audio lines. The
sensitivity of this circuit can be adjusted by R2. Some care
must be taken in making this adjustment so that hum and noise
will not falsely trigger the circuit. The audio monitor
terminals are transformer-coupled, DC blocked and electrically
isolated from the chassis. Approximately 200 VDC may be placed
across the terminals without damage.
*NOTE: Some installations may dictate hooking the audio monitor
to the receiver speaker terminals for an audio source.
This is generally not recommended because adjusting
station volume control too low will defeat the purpose of
the monitor and risk FCC citation.
14
Page 14