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Instrument Construction and Function Description
R&S ZVB
1145.1078.82 3.20
E-4
Motherboard
The motherboard supplies power to the boards and connects them to the control and data buses. A
number of RF connections are also routed via the motherboard.
As well as straight connections, a number of circuits are accommodated on the motherboard:
Motherboard controller (MBCON)
28 V supply
Preamplifier for the DC measurement inputs
Supply voltage fuses
Rear panel interfaces
Fan control
The
MBCON
unit acts as an FSU bus-slave:
•
to drive the LEDs (instrument front-panel)
•
to drive the fan in five stages
•
for two temperature sensors on the motherboard
•
for an SPI-EEPROM on the motherboard
•
Furthermore, the software can detect which device (R&S ZVB4 or R&S ZVB8) is present using the
MBCON.
In addition to the voltages delivered by the power supply, +28 V is produced from +12 V on the
motherboard by means of a boosting switching regulator. This voltage is required to operate the OCXO
on the reference board when option B4 is fitted.
Each board has its own fuses for the supply voltages. These fuses are soldered into position on the
board.
All external supply voltages (USB etc.) are protected to prevent shorts.
Board Replacement
The following section is a detailed description of board replacement. Chapter 5 tells you how to order
spare parts. It contains a list of mechanical parts and their order numbers as well as drawings relating
to board replacement.
Note:
The numbers in brackets are the item numbers in the list of mechanical parts in Chapter 5.
In turn, these item numbers are the same as the item numbers in the drawings relating to
board replacements (also in Chapter 5):
1145.1010 sheet 1 (R&S ZVB base instrument, Items 10-120, 260-470)
1145.1010 sheet 2 to 7 (R&S ZVB base instrument, Items 125-295)
1145.1290 sheet 1 (R&S ZVB fundamental unitt, Items 500-799)
1145.1332 sheet 2 (R&S ZVB metal frame, items 17-19)
1145.1384 sheet 1 (R&S ZVB display unit, Items 800-1060)
1145.1770 sheet 1 (R&S ZVB Option B4)
1145.3593 sheet 1 (8GHz Bridge)
1145.3664 sheet 1 (RM 4/8)
1145.4277 sheet 1 (RM20)
The terms “left” and “right” always mean left and right as seen looking at the front of the
instrument.
Summary of Contents for ZVB 14
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