Coupling and Directivity Tests

TB 9-5985-314-24

(d) AUX (TEST) SIDEARM PORT (if any) to 50 : 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

(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.

(d) AUX (TEST) SIDEARM PORT (if any) to 50 : 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.