HP 416A - Page 42

"""
L!)
-
r-
-
-
N
-
There now sho ul d be a connection ( 1) from the inciden t directional
coupler (Model S752D), through a barretter and its t r ansfo r mer , to
the INCIDENT/REFERENCE input on the Model 4 l 6A , and (2 ) from
the reflected di rection a l c o up ler (Model S7 5 2C}, through a barrette r
and its transforme r, to the REFLECTED /PROBE input on the . Model
416A .
CAUTION : Do not co nne ct· t he b ia s supply to the . transforme r assembl y
a t this tim e. The bias sup ply connection never should be
completed u nti l the Model 416A has been through a warm -
up peri od of app r o x imat ely five minutes.
6. Conn ect th e Mo d el S28lA adapter to the R. F . OUTPUT on the Model
670SM os cillator •. A Type AC - 16Q c able is suitab le for thi s connection.
This cable is not supplied ~ and may be procured from the Hewlett-
Pa c kard Company .
Model 416A Ratio Mete r - -
1. Plug the power ca ble i nto a power line of specified voltage and fre-
quency . Turn the powe r s wi tch to ON . Allow the instrument about
five minut es to re a ch a sta te of stable operation.
2 . With the Type·AC - 16A c able (dual banana plug to dual banan a p l ug ) sup -
plied with th e Type AC - 60K transformer assembly , c onn ec t the bias
current for the ba rret te r s to th e irnpedance - mat c hing transformers.
The b ia s su pply output te rmi nals ( J4-BIAS} are on the rear of the
Mod el 4 16A; the i np ut terminals (BIAS) are on the top of the trans -
forme r ass embly.
3. Ch ec k the position of th e EXCESS COUPLER LOSS switch . When a
20 = db (Model S752D) c oupler is u s ed to s ample the incident power , th e
sw itch should be set at 10 DB . If a 10-db ( Model S752C) coupler is
used to sample the inci de nt power, s et t he EXCESS CO UPLER LO SS
swi tc h a t 0 DB.
4. Conne c t th e OUTPUT/ J 3 c onnector {Type BNC) on the rear of th e
Mod el 4 16 A to th e vertical i nput of the oscill os c ope.
5. Che c k that the frequency and level
8
of the input signal voltage is within
op eratin g limit s. I nd i c ation t hat the inpu t signal is within frequ e n cy
and vo lta ge limits is given by the RF POWER MON I TOR (tu ning eye).
Input filte rs in th e Mo de l 416A a re sha rply tu ned to 1, 000 cycles.
Th erefore , regar d les s of input sig n al l evel, n o voltag e will re ach the
tuning eye circuit unless th e s ignal is within ±4 0 cycles of 1, 000 cy cl e s.
How e v er, when the input voltage is of correc t frequency, ah input signa l
8
The reflectome ter sys te m sho ul d b e operated at t he lowest practical input
power. When the input to t he crystal detecto r is wit hin the -5 0 dbn~ to -1 0 dbm
range~ , the det ector is o perati ng largely within it s li near region (Fig. 8}, an d
output c hara cteristics of the two crystal d etector s will come close to tracking .
A
br i ef dis cu ss i on of cry sta l d, etector c ha r acte r istics is given under Possib le
Error if I nput Power to Detector . T oo High, below.
- 27 -