Agilent Technologies 856290216 Video Output, Frequency Counter Prescaler/Conditioner

Video Output

1.On the HP 85623 spectrum analyzer, press C-1, C-1, 300 m, (SPAN), 100 (Hz), (m), -10 dBm, [WSWP), a and IF BJ OFF .

2.Connect the CAL OUTPUT to the INPUT 500 connector.

3.Disconnect W54 (coax 2) from A4J4. Connect a short SMB to SMB cable from A4J4 to an SMB tee and connect W54 to the tee. Connect a test cable from the tee to the input of an oscilloscope.

4.Set the oscilloscope controls as follows:

Amplitude scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . , 200 mV/div Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +400mV Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~dc Sweep time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 pus/division

5.The oscilloscope should display a 4.8 kHz sine wave.

6.Disconnect the cable from the CAL OUTPUT and the INPUT 5Ofl connectors.

7.Set the resolution bandwidth to 2 MHz.

8.Broadband noise should be displayed on the oscilloscope from approximately i-200 mV to t400 mV.

9.As the REF’ LK, is decreased in 10 dB steps from -10 dBm to -70 dBm, the noise displayed on the oscilloscope should increase in 100 mV increments. If this response is not observed, refer to “Step Gains” and “Video Offset” in this chapter.

10.Reconnect cable W54 to A4J4.

Frequency Counter Prescaler/Conditioner

Refer to function block Q of A4 Log Amplifier Schematic Diagram (sheet 4 of 4) in the

HP 8560 E-Series Spectrum Analyzer Component Level Information.

The frequency counter prescaler/conditioner divides the frequency by two, and then attenuates it. The circuit consists of frequency divider (U703A) and an output attenuator. The frequency divider turns on only when the instrument is counting.

AM/FM Demodulator

Refer to function block R of A4 Log Amplifier Schematic Diagram (sheet 4 of 4) in the

HP 8560 E-Series Spectrum Analyzer Component Level Information.

The demodulator circuitry on the log amplifier on A4 produces a low-level audio signal. This audio signal is then amplified by the audio amplifier on A4. The FM demodulator demodulates narrowband FM (5 kHz deviation) signals. The detector (block J) demodulates AM signals.

1.If demodulation problems occur when the spectrum analyzer is in the frequency domain, perform the Frequency Span Accuracy performance test and, if necessary, the YTO Adjustments procedure.

9-16 IF Section