MFJ MFJ-784B, Инструкция по эксплуатации, Страница: 23 / 74

MFJ-784B Instruction Manual
Installation Error! Main Document Only. -5
Passing Sidetone
You may perfer to listen to a station with different pitch than the sidetone of
your transmitter. In this situation, the DSP filter will attenuate the sidetone
and you will not be able to monitor your sending. There are two methods of
passing sidetone through the DSP filter.
T/R Connection
The preferred method for passing sidetone is the use of the T/R
(transmit/receive) line on the DSP's To Radio port. All filter functions are
bypassed when the T/R line is pulled low. The transceiver's sidetone and
audio monitoring functions will appear at the DSP output without digital
filtering.
The
T/R line should be connected to an output from your radio that is pulled
low when the radio goes into the transmit mode (such as an output for an
external RF amplifier). Radio manufacturers call such a line many different
names: Relay or RLY; NO or normally open; xmit, transmit or send; or maybe
even PTT.
If a linear amplifier is connected to the
T/R line, a diode (1N4001 or
equivalent) should be connected from the linear amplifier's control (relay) jack
to the
T/R line. This diode prevents the amplifier from loading the DSP's T/R
line when the amplifier is turned "off." The anode of the diode should be
connected to the amplifier and the cathode (banded end) to the
T/R line.
Refer to the diagram on 2-3.
Warning: Never connect the
T/R
line to negative voltages or to
positive voltage sources that exceed 35 volts.
The DSP has internal protection circuitry to help prevent other equipment
connected to the
T/R line (such as a linear amplifier) from damaging the unit.