Sim Interface Connector; Grounding - Stanford Research Systems SIM914 Operation And Service Manual

1.2 Operation
1.2 Operation

1.3 SIM Interface Connector

1.3.1 Grounding

SIM914 350 MHz Preamplifier
The SIM914 is typically installed in the SIM900 Mainframe, which
can accommodate up to eight SIM914s (plus one remote unit.) The
unit is on, as indicated by the front-panel Power LED, whenever the
mainframe has line power and is turned on.
The input impedance for each channel is 50 Ω. The DC input volt-
age must be limited to
end. The amplifier is internally protected from 50 V transients of 1 s
duration. The 50 Ω input impedance is intended to terminate 50 Ω
coaxial cable such as RG-58.
The amplifiers perform well when cascaded due to their high input
return loss and flat frequency response characteristics. Referenced to
the input, the broadband noise (1 Hz to 300 MHz) is 80 Vrms. Peak-
to-peak noise is typically 5 times the rms value. This corresponds to
about 10 mVpp at the output of two cascaded amplifiers, 50 mVpp at
the output of three cascaded amplifiers, and 250 mVpp at the output
of four cascaded amplifiers.
The DB-15 SIM Interface Connector provides power and overload
monitoring to the instrument. The connector signals are specified in
the table below.
Pin Name
1 SIGNAL GND
2 STATUS
6 5V
8 PS RTN
9 CHASSIS GND
13 +5V
Table 1.1: SIM Interface Connector pin assignments, DB-15. All other
pins are left unconnected on the SIM914.
In the SIM914, all three ground lines (Pins 1, 8 & 9) are tied common
to the chassis, and also form the signal ground.
4 V to avoid damaging the amplifier front-
Description
Ground
Overload (TTL output, active low)
Power supply
Ground
Chassis ground
Power supply
1 – 3