Operation; Signal Flow; Coupler Temperature; Figure 4-1 Signal Flow - Keysight 778D Operating And Service Manual

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Operation

Signal Flow

Unlike some other dual-directional couplers, this coupler is polarized. For best performance the
signal must flow through the coupler as shown in
on the label. DO NOT reverse the coupler since the directivity may be somewhat lower in the
reverse direction. To test devices with other types of connectors, another coupler with the correct
mating test port connector is recommended. Using an adapter will degrade the effective directivity
of the measurement.
Figure 4-1

Coupler Temperature

Operate the coupler at normal room temperature and do not temperature cycle the coupler in use
or storage. Heat cycling may degrade the performance of the coupler.
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Signal flow

Figure 4-1. Observe the TEST PORT designation
Keysight 778D Operating and Service Manual