HP 416A - Calibration (100% Reflection, Broadband)

a. To a d just the E'l odulation f:ce q ue:i: ,. cyo n the input signal :
( ] )
(2)
If
there i s a n exter na l at tenu at or in the line, s e t it a t approxi-
m a t e l y 5 DB . ~ T h e setti ng cf the lvfodel 670HM is at O. } !f
the r e is no ex t er na l attenuator in the line, change the setting
of the ATTEN U AT I ON c ont rol on the M ode l 670H M from 5 to
a
pp ro xi mat el y 4.
1£ the tuning eye does not indicat e by n-wving its shutter toward
c l os u re , SLOWLY adjust the MOD. FREQ . control on the
M od e l 7 1 7 A until the tuning e ye shutter p ea ks . Start i ng from
th e ext re me clock w ise pos iti on of MOD . FREQ. , slowly turn
th e cont r ol counte rcl ockwise until a tuning eye indication is
obtai ned . ( If th e eye shutter does not move, return MOD .
F
REQ . to i ts e' xtre m e cl oc k w ise position, set the ATT E NUA-
TION contro l on the Model 670HM at 3 , and readjust the MOD.
F REQ. control on the Model 717A until a tuning eye indication
•
is obta in ed .)
C AUTI ON : Care should be taken to make certain that the
correct modulation frequency is chosen and not
some subharinonic of 1, 000 cycles . For a l, 000-
cycle output, the MOD. FREQ. control knob setting
wi ll be almost completely clockwise.
b. If the tuning eye overlaps by mo r e than 1/32
11
, reduce the level of
the input signal.
(1) If there i s an externa l attenuator in the line , increase the setting
of the attenuator, as required, to bring the tuning eye overlap
to 1/32
11
or le ss . Leave the setting of the Model 670HM AT -
TENUATION contro l at O.
(2) If there i s no external attenuator, reduce the level of the outpu t
signa l at t he Model 670HM by adjusting the setting of the AT -
TENUATION control.
Calibration ( 100% Reflection, Broadband )
1. On the M od el 670HJ\1. Osci llat or :
a. On the FREQUENCY -KMC dia l, set the frequency -li miting stops
for the des ire d range. For the X-band system being described ,
set one limit stop at 8. 2 kmc and th e other at l 0 krnc. Lock the
limit stops.
b. Check that the SELECTOR swi tch is at MANUAL.
2. Disconne c t the load, and place a shorting element across the output of
the reflec t ed directional couple r. This places a short across the line
(to p rovide a known [10 0% ] reflection).
- 1 .s -