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Dishtronix, Inc.
Dx2400l1 instruction manual rev00.doc 06-10-18 5.14
Page 31/44
3.10.1
SWR Protection
High SWR is the main cause of failure in any solid state amplifier, because high voltage can be
reflected to the final transistors, or the transistors can attempt to pass currents beyond their
permissible ratings into an impossible (low) impedance, or a combination of the two.
Should the transistors see more than approximately 250 W (internally adjustable) of reflected
power, or approximately an SWR of 2.5, the SWR hardware protection will activate and place the
amplifier in the BYPASS mode. The appropriate fault code will be displayed on the front panel.
Note that high SWR may also cause the current protection feature to activate. In addition to high
SWR on the antenna, manually selecting the wrong band of operation will cause the SWR
protection feature to activate.
3.10.2
Overdrive Protection
Another common cause of failure in solid state amplifiers is overdrive. Driving an amplifier
beyond its designed maximum input level can cause the transistors to attempt to amplify beyond
their current capability, causing failure. Unfortunately several solid state transmitters have a full
power output spike when they are keyed that can cause this condition. There is not a lot an
amplifier manufacturer can do to remedy faults in the design of another companies transmitter.
One solution may be to activate the internal 3dB attenuator which doubles the input drive
requirement. See Section 3.6 to activate the input attenuator.
Should the amplifier be overdriven, for example on voice peaks, the front panel OVERDRIVE
indicator will flash, and the amplifier will enunciate with an audio chirp starting at about 2 KW
(internally adjustable). Should the amplifier be severely overdriven beyond this to approximately
2.4KW (internally adjustable), the overdrive fault protection will activate and place the amplifier
in the BYPASS mode. The appropriate fault code will be displayed on the front panel. Note that
overdrive may also cause the current protection feature to activate.
3.10.3
Over Current Protection
As mentioned above, overdrive and / or high reflected power (SWR) can cause potentially
damaging high currents in the RF output transistors. The current consumed by each power
module is individually monitored by the protection circuit as well as the microprocessor control.
Should the current of any module exceed a preset level, the over current protection feature will
activate and place the amplifier in the BYPASS mode. The appropriate fault code will be
displayed on the front panel.
Note that the measured DC supply current of each power module, as well as the total power
supply current is available for monitoring over the built in RS422/RS485 interface. See the
DX2400L1 Interface Programming Manual for details.
3.10.4
Power Supply Over Voltage Protection
If the power supply voltage is too high, beyond approximately 80V (software adjustable), the
amplifier will enter the BYPASS mode and display the appropriate fault code on the front panel.
If using the companion LPS4800 Linear Power Supply, the line voltage tap may need to be
changed. Refer to the power supply manual for details on setting the voltage. The high current
DC supply voltage is also available for monitoring over the interface. See the DX2400L1
Interface Programming Manual for details.
Summary of Contents for DX2400L1
Page 11: ...Dishtronix Inc Dx2400l1 instruction manual rev00 doc 06 10 18 5 14 Page 11 44 2 INSTALLATION...
Page 19: ...Dishtronix Inc Dx2400l1 instruction manual rev00 doc 06 10 18 5 14 Page 19 44 3 OPERATION...
Page 41: ...Dishtronix Inc Dx2400l1 instruction manual rev00 doc 06 10 18 5 14 Page 41 44 5 SERVICE...
Page 44: ...Dishtronix Inc Dx2400l1 instruction manual rev00 doc 06 10 18 5 14 Page 44 44 NOTES...