HP 416A - Page 23

b. Connect the Model 670HM to the Model 71 7 A by plugg i ng the out -
put cable (the other e nd of which is a ttached into the Model 670HM
oscillator) into t he te r minal assembl y on the Model 717A control
panel.
c. Plug the power cable (connected to the Model 717A on the rear of
the instrument) into a power source ( 115 - volt , 50 - 60 cycle). Turn
the POWER switch to the on position .
d. Set BEAM VOLTS at 800 , MOD , SELECTOR at CW .
e. Set REFLECTOR RANGE at 600 .
L Set BEAM VOLTS at proper v oltage (1, 000 volts for the Model
670HM ; see T a ble at end of section for beam voltage for the other
oscillators ).
g.
On the Mod el 67 0HM , s e t the FREQUENCY - KMC dial at 7. 5 kmc.
h . Adjust BIAS VOLTS to obta in be am c urren t of 20 ma , with the MOD.
SELECTOR s wi tch (on Model 717 A) in the CW position .
i. On the Model 6 7 0HM , set the SELECTOR switch at MANUAL .
j . Set MOD . SELECTOR ( on Model 7 17A) to G - INT . MOD .
k .
Set MOD , AMP . (on Model 71 7 A ) to appro x imately full clockwise
po s ition .
Waveguide - The ne xt s t ep is t o asse mble t he wavegu i d e, i n the follow i ng se -
quence :
2
1. To a Mod e l X 7 52D (2 0 - db ) D ire c ti on a l Coupler conne c t a Model X752C
( 10 - db) Di re c ti on a l Coupl er , b ack ~ to - b ac k . The Model X752D coupler
samples the i n ci d e n t p o wer ; th e M o del X75 2C coupler s a mples the re -
flected power .
NOTE : A 10 - db di r ectiona l c oup ler m a y be us ed to sam~le th e incident
po wer, if d esire d , b ut a n a d vanta ge i n accuracy may be ga ined
by th e us e of a 2 0 - db c oup ler i n the i n ci dent channel of the system .
2 .
Connec t a Mo del X281 A W ave gui d e to Co a xi a l Adapter to t he i nput to the
inciden t couple r ( Mod el X 752 D).
NOTE : If a wa v egu id e att enua to r i s beingu s ed(Model X382A , X370B
or C , or X 37 5A ), conne ct the attenuator between the Model
X 28 1A Wa ve gui d e to Coa xia l Adapter and t he input to the in -
ci den t c oupl er ( Mod e l X75 2D ) . Set the waveguide attenuator
for 10 - 20 db loss .
3. Connect the unkno wn lo a d to the ou t put of the reflected coupler
(Model X 7 52C ).
See Possible Errors if Inpu t Powe r to Detecto r Too High and Spurious Signals
Due to Detector Mismatch , belo w.
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