Agilent Technologies 856290216 service manual Rosenfell Detector, Adc Mux

Rosenfell Detector

Refer to function block S of A3 Interface Assembly Schematic Diagram in the

HP 8560 E-Series Spectrum Analyzer Component Level Information.

If both HPOS-HLDNG and HNEG-HLDNG are high during the same bucket, HROSENFELL will also be set high. This indicates that the video signal probably consists of noise, since it rose and fell during the same period. The HROSENFELL signal is valid only when the NORMAL ( rosenfell) detector mode is selected.

1.Remove anything connected to the HP 85613 or HP 85633 front-panel INPUT 500 connector. Press [?iZZ) on the spectrum analyzer and set the controls as follows:

Centerfrequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..300MHz Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz Sweep time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5s Detector mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NORMAL

2.Check LPOS-RST and LNEG-RST as described in “Peak Detector Reset.”

3.Check A3U423 pin 4 for two low-going 3.3 ps pulses 40 ps apart occurring every 130 ,us.

4.Check that HROSENFELL (A3U610 pin 6) has two pulses spaced approximately

40 ps apart and then a third pulse 60 ~LS from the second pulse. Each pulse should be approximately 10 ps wide and low-going.

5.Monitor HROSENFELL with an oscilloscope while reducing the video bandwidth from

1MHz to 1 kHz.

6.As the video bandwidth is decreased to 1 kHz, the HROSENFELL line should increasingly show a low logic level. With a video bandwidth of 1 kHz, a nearly flat line should be displayed on the CRT.

7.Set the sweep time to 50 ms. Externally trigger the oscilloscope using the spectrum analyzer rear-panel BLKG/GATE OUTPUT.

8.Check that HPOS-HLDNG (A3U416 pin 4) is mostly high with a 1 MHz video bandwidth and mostly low with a 1 kHz video bandwidth.

9.Check that LNEG-HLDNG (U408A pin 13) is mostly high with a 1 MHz video bandwidth and mostly low with a 1 kHz video bandwidth.

ADC MUX

Refer to function block AA of A3 Interface Assembly Schematic Diagram in the

HP 8560 E-Series Spectrum Analyzer Component Level Information.

The ADC MUX switches various inputs into the video path for conversion by the ADC. The SCAN RAMP input is used during sweeps having a’width of equal to or greater than

2.01MHz times N, to control the timing of the ADC operations. Some combination of MOD-VIDEO, NEG-PEAK, and POS-PEAK is used for the video signal to be converted by the ADC. The YTO ERR, FCMUX, CAL OSC TUNE, and OFL ERR inputs are used only during diagnostic and auto adjust routines and during retrace.

ADC/lnterface Section 8-21