Rohde & Schwarz SMB100A - Troubleshooting - Reference Oscillator option R&S SMB-B1

Troubleshooting R&S SMB
1407.0806.82 3.30 E-6
Troubleshooting B Reference Oscillator option R&S SMB-B1
If the frequency Error of the R&S SMB is > 3*10
-6
the Reference Oscillator is defective, change the
module.
Input and Output Signals
The Reference Oscillator has only one Futurbus connector (X1). The Reference Oscillator is plugged into
the RF Board (X221 see Fig. 3-8). All signals and the supply voltage are fed to the module through this
connector. Check the voltages for the OCXO being according to the following table. To test the serial bus
signals watch the signal lines while toggling between internal and external reference with an
Oscilloscope. Voltage Levels are 0 V and 3.3 V.
Fig. 3-8 Pin location X221 on RF Board
Pin of
X221
RF Board
Voltage/
Signal
Pin of
X221
RF Board
Voltage/
Signal
Pin of
X221
RF Board
Voltage/
Signal
Pin of
X221
RF Board
Voltage/
Signal
A1
Clock-signal
serial bus
B1 NC C1 GND D1
+4.8 V -
+5.6 V
A2
Data-signal
to option
serial bus
B2
0 V
when
Oven Cold
C2 NC D2
0 V
when
option fitted
A3
Chip Select
signal
serial bus
B3
Data-signal
from option
serial bus
C3
+5.0 V
when
option on
D3
A4 NC B4 NC C4 NC D4
10 MHz
LVDS
signal
A5 NC B5 NC C5 GND D5 GND
A6
+4.8 V -
+5.6 V
B6
+4.8 V -
+5.6 V
C6
+11 V –
+14 V
D6
-8 V –
-12 V