Technical Manual Appendices
© SPECTRA ENGINEERING 2006 Revision 4.2.3
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7.1.2 CN2 DB9 Female Monitor Connector
This port provides monitor and test functions for the MX800. It may be
optionally located on the front panel of the MX800. The functions of the pins
are described in Table 7-3 below.
Pin No
Function
1 EARTH. General earth common for VF input and output.
2 RX RSSI OUTPUT. The receiver's received signal strength indicator voltage
is proportional to the log of the signal level at the antenna input. Voltage
range is 0 to 5 volts. Output impedance is low. Dynamic range > 60dB.
3 EXTERNAL PTT INPUT OR MONITOR POINT. Input or output. Wired in
parallel with the normal PTT via a 10K isolating resistor This input can
override the normal PTT input on the DB15. Refer CCT.
4 TX FORWARD POWER. The voltage from the forward power directional
coupler in the Power Amplifier goes directly to this pin via a buffer. The
voltage should be about 3-4 Volts for 50 Watts.
5 +12 VOLTS OUTPUT. +12 Volt output to power small external devices or
interfaces. Max load 500mA.
6 TX REFLECTED POWER. The voltage from the reflected power directional
coupler in the Power Amplifier goes directly to this pin via a buffer. For a
50Ω terminated PA the voltage should be less than 200mV
7 MUTED RX VF. Monitor point and buffered output from the muted RX VF
section.
8 FINAL TX VF MONITOR. Monitor point for buffered audio fed to TX
VCO input.
9 TEST TX VF INJECT. Wide band audio or data may be connected to this
point. In order to conform to transmitter bandwidth emissions limits, this
input is hard limited to the nominal deviation and Bessel filtered -3dB @
3400Hz for minimum group delay distortion. Input impedance is >10KΩ AC
coupled. If this input is not used then do not connect any wires to this pin.
Also avoid the use of ribbon cables longer than 30-50cm as this may also
result in excess coupling or crosstalk.
Table 7-3 CN2 Connections
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