Chapter 7
371
ADC/Interface Section
A3 Assembly Video Circuits
Log Offset/Log Expand
Refer to function block X of A3 Interface Assembly Schematic
Diagram (sheet 5 of 6) in the
HP 8560 E-Series Spectrum Analyzer
Component Level Information
.
The log scales are modified using a combination of amplification and
digital trace manipulation. The video input to the A3 assembly is either
10 dB/div or linear. To obtain the 5 dB/div scale, the CPU manipulates
the trace data from the 10 dB/div scale. To obtain the 2 dB/div scale, the
video signal is amplified and offset so that top-screen in 10 dB/div
corresponds to top-screen in 2 dB/div. To obtain the 1 dB/div scale, the
CPU manipulates trace data from the 2 dB/div scale.
In 2 dB/div, Log Offset/Log Expand amplifies the top 20 dB of the
display. This is done by offsetting the video signal by
−
0.8 V and
providing a gain of 5 to the top 0.2 V of the video signal. The
−
0.8 V
offset is accomplished by sinking 2 mA through R114 by current source
U105/Q101.
1. On the HP 8560E/EC, press
PRESET
,
SPAN
,
ZERO SPAN
,
CAL
, and
IF
ADJ OFF
.
2. Disconnect W26 (coax 2) from A3J101 and connect the output of a
function generator to A3J101.
3. Set the function generator to the following settings:
Output ................................................................. Sine wave
Amplitude ........................................................ 1 V pk-to-pk
DC Offset .............................................................. +500 mV
Frequency ................................................................... 50 Hz
4. Set the HP 8560E/EC sweep time to 50 ms.
5. Adjust the function generator amplitude and offset until the sine
wave fills the entire graticule area.
6. Measure and note the function generator peak-to-peak voltage using
an oscilloscope.
V
(10 dB/div)
=______________________________V
7. Set the HP 8560E/EC to 2 dB/div.
8. Readjust the function generator amplitude and offset until the sine
wave again fills the entire graticule area.
9. Measure the function generator peak-to-peak voltage and dc offset.
V
(2 dB/div)
= ______________________________V
10.The ratio of voltage recorded in step 6 to the voltage recorded in step
9 should be 5
±
3%. If the ratio is not 5, troubleshoot the A3 assembly.
11.Reconnect W26 to A3J101.
Summary of Contents for 8560E
Page 17: ...16 Contents ...
Page 24: ...23 1 General Information ...
Page 49: ...48 Chapter1 General Information Sales and Service Offices ...
Page 50: ...49 2 Adjustment Procedures ...
Page 132: ...131 2a Adjustment Procedures HP 3335A Source not Available ...
Page 146: ...145 3 Assembly Replacement ...
Page 224: ...223 4 Replaceable Parts ...
Page 251: ...250 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 253: ...252 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 255: ...254 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 257: ...256 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 259: ...258 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 261: ...260 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 263: ...262 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 265: ...264 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 267: ...266 Chapter4 Replaceable Parts Firmware Dependent Part Numbers ...
Page 268: ...267 5 Major Assembly and Cable Locations ...
Page 279: ...278 Chapter5 Major Assembly and Cable Locations Introduction Figure 5 9 Front End ...
Page 281: ...280 Chapter5 Major Assembly and Cable Locations Introduction ...
Page 282: ...281 6 General Troubleshooting ...
Page 285: ...284 Chapter6 General Troubleshooting Introduction Figure 6 1 Assembly Test Points ...
Page 286: ...Chapter 6 285 General Troubleshooting Introduction Figure 6 2 Ribbon Cable Connections 1 of 3 ...
Page 287: ...286 Chapter6 General Troubleshooting Introduction Figure 6 3 Ribbon Cable Connections 2 of 3 ...
Page 290: ...Chapter 6 289 General Troubleshooting Introduction Figure 6 5 Service Cal Data Menu ...
Page 331: ...330 Chapter6 General Troubleshooting Block Diagram Description Figure 6 6 Functional Sections ...
Page 343: ...342 Chapter6 General Troubleshooting Block Diagram Description ...
Page 345: ...344 Chapter6 General Troubleshooting Block Diagram Description ...
Page 347: ...346 Chapter6 General Troubleshooting Block Diagram Description ...
Page 349: ...348 Chapter6 General Troubleshooting Block Diagram Description ...
Page 351: ...350 Chapter6 General Troubleshooting Block Diagram Description ...
Page 353: ...352 Chapter6 General Troubleshooting Block Diagram Description ...
Page 354: ...353 7 ADC Interface Section ...
Page 406: ...405 8 IF Section ...
Page 436: ...Chapter 8 435 IF Section A5 IF Assembly Figure 8 3 IF Adjust Signature ...
Page 437: ...436 Chapter8 IF Section A5 IF Assembly Figure 8 4 Detailed IF Adjust Signature 1 ...
Page 438: ...Chapter 8 437 IF Section A5 IF Assembly Figure 8 5 Detailed IF Adjust Signature 2 ...
Page 439: ...438 Chapter8 IF Section A5 IF Assembly Figure 8 6 Detailed IF Adjust Signature 3 ...
Page 440: ...Chapter 8 439 IF Section A5 IF Assembly Figure 8 7 Detailed IF Adjust Signature 4 ...
Page 441: ...440 Chapter8 IF Section A5 IF Assembly Figure 8 8 Detailed IF Adjust Signature 5 ...
Page 443: ...442 Chapter8 IF Section A5 IF Assembly Figure 8 9 Noisy Signature ...
Page 444: ...Chapter 8 443 IF Section A5 IF Assembly Figure 8 10 Noise with Correct Shape ...
Page 445: ...444 Chapter8 IF Section A5 IF Assembly Figure 8 11 Region B Amplitude Variation ...
Page 447: ...446 Chapter8 IF Section A5 IF Assembly Figure 8 13 Faulty Crystal Short ...
Page 463: ...462 Chapter8 IF Section Cal Oscillator Assembly P O A4 ...
Page 465: ...464 Chapter8 IF Section Cal Oscillator Assembly P O A4 ...
Page 467: ...466 Chapter8 IF Section Cal Oscillator Assembly P O A4 ...
Page 469: ...468 Chapter8 IF Section Cal Oscillator Assembly P O A4 ...
Page 470: ...469 9 Controller Section ...
Page 486: ...Chapter 9 485 Controller Section Display Problems 8560E Figure 9 10 Delta Y Waveform ...
Page 503: ...502 Chapter9 Controller Section Keyboard Problems ...
Page 505: ...504 Chapter9 Controller Section Keyboard Problems ...
Page 506: ...505 10 Synthesizer Section ...
Page 577: ...576 Chapter10 Synthesizer Section A21 OCXO ...
Page 579: ...578 Chapter10 Synthesizer Section A21 OCXO ...
Page 581: ...580 Chapter10 Synthesizer Section A21 OCXO ...
Page 582: ...581 11 RF Section ...
Page 598: ...Chapter 11 597 RF Section A14 Frequency Control Assembly Figure 11 2 A7 LODA Drive ...
Page 617: ...616 Chapter11 RF Section A10 Tracking Generator Option 002 ...
Page 618: ...617 12 Display Power Supply Section ...
Page 651: ...650 Chapter12 Display Power Supply Section A6 Power Supply Assembly ...
Page 653: ...652 Chapter12 Display Power Supply Section A6 Power Supply Assembly ...
Page 654: ...653 13 Component Level Information Packets ...
Page 660: ...Chapter 13 659 Component Level Information Packets Introduction ...