Plug the SP75 output cable into the TR7 microphone input connector. Plug the
phono plug on the SP75 supply cable into the 13.6 volt accessory output jack on
the PS7 power supply. The microphone may then be connected to the SP75
input.
If another transmitter other than the TR7 is used, the proper mating connector
can be installed on the SP75 cable replacing the TR7 microphone plug sup-
plied. Connect the red wire to the PTT connection, the white center conductor of
the shielded cable to the microphone audio connection, and the shield and
black wires to the ground connection.
When using a transmitter/power supply combination other than the
TR7/PS7,
connect the positive SP75 supply (11-16 V) lead to the tip of the SP75 supply
cable plug. Connect the negative supply lead to the
chassis of the transmitter.
Do not connect the negative supply lead to the shield of the SP75 supply cable
as this shield is not internally connected in the SP75.
The
SP75 must receive its
supply negative connection through the output cable ground by way of the
transmitter or transceiver chassis. This is done to prevent ground currents
from being introduced across the SP75 output cable which could result in an
RF feedback condition.
ADDITIONAL GROUNDING NOTES
I
In addition to the above supply connection the following must be observed to
prevent any possibility of creating undesirable ground currents through the
SP75 which could result in RF feedback.
1)
Any microphones or other inputs connected to the SP75 MUST NOT be
grounded through any other path other than through the SP75 input
connector.
2) When a phone patch or tape recorder are connected to the SP75, they should
NOT be grounded elsewhere, such as through a three wire AC supply cord. If
the patch or recorder must be grounded, then the audio connection to the
SP75 may need to be isolated by a transformer.
3) See
the following diagrams for examples.
3
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