Coaxial Cable Test-continued

TM 11-5820-695-35

(4) Adjust the incident wave voltage step to

coincide with the center screen graticule line of the

oscilloscope using the VERT POSITION control.

(1) Connect the two elbow adapters to bridge

(5) Remove the 50 ohm termination and

the STEP OUTPUT jack to the SIGNAL IN jack on the

insert the calibrated 1.1 VSWR mismatch (Mecca model

front panel of the reflectometer, and connect the

400-1.10). Note the upward deflection point on the

GR874-to-N adaptor and the UG-29B/U adaptor to the

oscilloscope, this represents an SWR of 1.1. Therefore,

SIGNAL OUT jack on the front panel of the

the increments between the 50 ohm terminated center

reflectometer.

scale and the 1.1 SWR calibrated line indicate values of

(2) Place POWER switch to ON and set the controls on

SWR between the nominal SWR of the 50 ohm

the reflectometer to the following positions:

termination (typically 1.05 residual SWR) and the

calibrated 1.1 SWR reference line. The 1.1 SWR

Control

Position

reference point can be adjusted to some convenient

OM LINE/OM DISLAY ---------------- 20

graticule line using the VERNIER CAL adjust (inner

MAGNIFIER ------------------------------ 6

control of the REFL COEFFICIENT controls).

MAGNIFIER DELAY . ------------------ 4

REFL COEFFICIENT ------------------- 0.5

SWEEP ------------------------------- NORMAL

(6) Remove the calibrated mismatch from the

SIGNAL OUT jack and connect the coaxial cable to be

tested to the SIGNAL OUT jack using the adaptor

(3) Connect 50 ohm termination HP-908A to

GR874B-toOSM J. Observe the oscilloscope to

the SIGNAL OUT Jack using the adapters installed in

determine if the coaxial cable being tested meets the

step (1).

1.1 VSWR criteria.

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