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1 OPERATING INSTRUCTIONS
Changes or modifications not expressly approved by
RF Technology could void your authority to operate this
equipment. Specifications may vary from those given in
this document in accordance with requirements of local
authorities. RF Technology equipment is subject to
continual improvement and RF Technology reserves the
right to change performance and specification without
further notice.
1 Operating Instructions
1.1 Front Panel Controls and Indicators
1.1.1 PTT
A front-panel push-to-talk (PTT) button is provided to facilitate bench and field tests
and adjustments. The button is a momentary action type. When keyed, audio from
the line input is disabled so that a carrier with subtone is transmitted. The front-
panel microphone input is not enabled in this mode, but it is enabled when the PTT
line on that socket is pulled to ground.
1.1.2
Line
The LINE trimpot is accessible by means of a small screwdriver from the front panel
of the module. It is used to set the correct sensitivity of the line and direct audio
inputs. It is factory preset to give 60% of rated deviation with an input of 0dBm
(1mW on 600 Ω equivalent to 775mV RMS or about 2.2V peak-to-peak) at 1kHz.
The nominal 60% deviation level may be adjusted by measuring between pins 6 and
1 on the test socket, and adjusting the pot. By this means an input sensitivity from
approximately -30dBm to +10dBm may be established.
An internal jumper provides a coarse adjustment step of 20dB. Between the jumper
and the trimpot, a wide range of input levels may be accommodated.
RF Technology T220
WARNING
Page 5
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