Daniels Electronics MT-3 Instruction Manual page 14

10
Theory of Operation
Amplifier Circuits
The MT-3 series Amplifier has six connections that are cabled to the transmitter board:
• +13.8 VDC
• +9.5 VDC
• Enable
• Forward Power Sense
• Reverse Power Sense
• Ground
The +13.8 VDC supply (JP1-3) is always on while the +9.5 VDC supply (JP1-2) is always switched by
a PTT signal. The enable line (JP1-1) is active low and is controlled by the Qualified PTT signal from
the synthesizer module.
Jumpers J12, J13, J14 and J15 are used to configure the amplifier's forward and reverse power sense
lines (JP1-4 and JP1-5). Normally jumpers J13, J14 and J15 are in the X position, which directly
connects the amplifier's forward and reverse power sense lines to the backplane connector (pins B26
and Z26 respectively).
The forward and reverse power sense lines from the amplifier can be open collector or linear outputs
depending on how they are configured in the amplifier module. In open collector configuration, the
lines are active low, that is, the output will go low when a "fail" condition is detected. If both lines from
the amplifier module are configured as open collector outputs, the power sense lines can be 'OR'ed
together to make a general fail indicator (jumper J12 in, jumpers J13, J14 and J15 in the Y position).
The Fail Indicator is also an open collector output; however, the Fail Indicator is active high (the
output goes high when a "fail" condition is detected). When the transmitter is configured with the
general fail indicator option, pin Z26 (VSWR reverse) is not used and pin B26 becomes the Fail
Indicator output.
MT-3 FM Transmitter Mainboard Instruction Manual
IM20-MT3TXMN