User's Manual

Model 1150A DVOR
2-28 Rev. - November, 2008
This document contains proprietary information and such information may not be disclosed
to others for any purposes without written permission from SELEX Sistemi Integrati Inc.
20 dB Attenuator
50 OHMs
20 dB Attenuator
50 OHMs
20 dB Attenuator
50 OHMs
20 dB Attenuator
50 OHMs
50 OHMs
STANDBY
CARRIER
SIDEBAND 1
SIDEBAND 2
SIDEBAND 3
SIDEBAND 4
CARRIER
FORWARD
CARRIER
REFLECTED
Forward
Detector
Reflected
Detector
Audio Generator 1,2
Carrier Amplifier 1,2
Monitor 1,2
Audio Generator 1,2
DC-DC
Converter
48 V1
48 V2
Standby
Detector
Monitor 1,2
Audio Generator 1,2
+ 5V
Temperature Sensor
Storage memory
(EEPROM)
RMS Parallel
Data (SPI)
Figure 2-11 RF Monitor Assembly Block Diagram
2.3.2.8.1
RF Monitor Assembly (1A2) Detailed Circuit Theory
The RF Monitor Assembly functions as an RF Detector/Amplifier and distributor of the detected analog RF signals.
The assembly contains a high power dummy load that is capable of dissipating the 100 watts of RF power from the
standby transmitter. Four dummy loads are mounted to the assembly heat sink in order to dissipate the sideband
generator power.
Refer to Figure 11-22. Resistor R84 is the dummy load for the standby transmitter RF carrier power. The RF power
enters the assembly via RF connector P1:F. A sample of the RF signal applied through C34 to the 35 dB attenuator
formed by R65, R66 and R67. The signal then enters the linear detector circuit U17. The detected voltage from U17
is buffered and amplified by U18A. Potentiometer R3 is located on the front panel of the RF Monitor and allows
adjustment of the output level. The technician uses this adjustment to calibrate the Transmitters>>Data>>Standby
Power to the same as measured by external test equipment while on the antenna.