TB 9-5985-314-35
(c) OUTPUT PORT to 50 Ω termination.
(d) AUX (TEST) SIDEARM PORT (if any) to 50 Ω termination.
NOTE
Ensure receiver system is in measurement mode.
(28) Record receiver system indication. Receiver system indication will be within the
Nominal Coupling (Coupling Variation) (Frequency Sensitivity) tolerances listed for TI
in Appendix A.
(29) Establish a 0.00 dB reference on receiver system.
(30) Connect TI as shown in figure 3 equipment setup as listed in (a) through (d) below:
(a) OUTPUT PORT to POINT A.
(b) SIDEARM PORT to POINT B.
(c) INPUT PORT to 50 Ω termination.
(d) AUX (TEST) SIDEARM PORT (if any) to 50 Ω termination.
NOTE
Ensure receiver system is in measurement mode.
(31) Record receiver system indication. Receiver system indication will be greater
than or equal to the value listed for TI in directivity column, Appendix A.
(32) Repeat technique of (20) through (31) above for remaining test frequencies
recorded in 8 c above.
b. Adjustment. No adjustments can be made; however, a correction chart may be
prepared listing actual coupling and directivity values at test frequencies.
NOTE
When determining directivity, in- or out-of-tolerance condition,
all of the below must be considered:
1. Termination mismatch errors can cause
measured
directivity to appear slightly lower than normal.
2. A 10 percent variation in directivity is acceptable for most
directional couplers used in direct support of field activities in
the U. S. Army.
3. A directional coupler may be out of tolerance at a specific
frequency and still be useable over the rest of its range.
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