User manual

Model 6220/6221 User’s Manual Output Connections 2-3
Return to Section 2 topics
shield connection setting. See “Triax Cable Guard” on page 2-8 for details on
using the Cable Guard.
Outer shield – The outer shield of the triax connector is always connected to
Earth Ground of the Model 622x (see “Ground points” for details).
Frequency variable resistor (FVR)
The outer shield (Earth Ground) of the triax connector is isolated from the chassis
of the Model 622x by a Frequency Variable Resistor (FVR). The FVR (shown in
Figure 2-1) is used to isolate the current source circuitry from high frequencies
that may be present on the chassis of the Model 622x. As frequencies on the
chassis increase, the resistance of the FVR increases to dampen its effects.
Ground points
The various ground points used by the Model 622x are shown and explained in
Figure 2-1. The ground point for signal connections to external circuitry is Earth
Ground. Earth Ground is the outer shield of the triax connector and is isolated
from the Chassis by the FVR.
Keep in mind that the Chassis should never be used as a ground point for signal
connections. High frequencies present on the chassis of the Model 622x may
result in higher noise on the output.
The Chassis should only be used as a safety shield. Use the Chassis Screw for
connections to the chassis of the Model 622x.
LO and GUARD banana jacks
The LO and GUARD banana jacks are located on the rear panel and are shown in
Figure 2-2.
Figure 2-2
LO and GUARD banana jacks
LO banana jack
The LO banana jack is electrically identical to the Output Low accessed at the
triax connector. However, when using the CABLE GUARD and FLOATING triax
settings, Output Low is not available at the triax connector. The LO banana jack
must be used as Output Low (see “Output configurations” on page 2-5 for details
on the triax connector settings).
GUARDLO
105Vpk