Agilent Technologies 856290216 service manual Bit Flash ADC, 32 ADC/lnterface Section

11.Measure the dc level of the flash video at TP27. The level should be near 0 Vdc with the signal at the bottom graticule line (no input to the spectrum analyzer).

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

13.Measure the dc level of the flash video at TP27. The level should be near t1.7 Vdc.

8-Bit Flash ADC

Refer to function block I of the Al6 fast ADC assembly schematic diagram in the

HP 8560 E-Series Spectrum Analyzer Component Level Information.

The flash ADC (U35) converts the analog video signal into 8-bit digital values at a fixed rate of 12 megasamples per second.

Note	When measuring voltages or waveforms on the Al6 fast ADC assembly,
	connect the ground (or common) lead to the ground-plane trace on the Al6
	assembly. This digital ground plane is totally isolated from the chassis.

1. Press [PRESET) on the Option 007 spectrum analyzer and set the controls as follows:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz Reference level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -20 dBm Log/division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 dB/DIV Sweep time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20ms

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

3.Pins 4 through 10 (ADC7-ADCl) and pin 21 (ADCO) of U35 should all be high (logic l), corresponding to an ADC digital count of 255 for the analog input of +2 volts or greater.

4.Disconnect the CAL OUTPUT signal from the INPUT 50R connector.

5.Pins 4 through 10 (ADC7-ADCl) and pin 21 (ADCO) of U35 should all be low (logic 0), corresponding to an ADC digital count of zero for the analog input of 0 volts or less.

8-32 ADC/lnterface Section