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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