15-8
Diagnostics Theory
RF_DIAGS
RF Detectors 1
Thelow and high sensitivity detectors are checked both with and without a signal present.
Step Attenuator
The step attenuator is checked by switching in one pad at a time.
RF Detectors 2
The filter output detector is checked with no signal present.
Filter Output Detector, Signal Present
The filter output detector is checked with a signal present at different frequencies.
Output Filter Rejection
Each filter is checked to see that it rejects frequencies outside its passband.
Output Variable Attenuator
Thevariable attenuator is checked by programming the DAC to full scale, then reading the
voltageon the output detector. Then the DAC is programmed to values which turn on the 5
most significant bits one at a time, starting with the MSB and measuring the detector
output each time.
Autorange Attenuator
The autorange attenuator is programmed to each of its possible values and the output
detector is measured each time.
Counter With TTL Dividers
The signal from the RF generator is routed to the counter TTL prescalers. The frequency
of the signal is set to all values between 10 and 250 MHz in 5 MHz steps.
Counter With ECL Dividers
The signal from the RF generator is routed to the counter ECL prescalers. The frequency
of the signal is set to all values between 50 and 1000 MHz in 50 MHz steps.
Temperature Sensor
The temperature sensor produces a DC voltage proportional to the internal temperature.
RF Analyzer Step Loop
This test checks the A17 Step Loop B assembly.