Tesla BM 510, Инструкция по эксплуатации

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Potfebujeme-li mëfit fâzovÿ posuv dvou napëti
stejného kmitoćtu, pfivedeme jedno z nich na
vertikâlni, drulié na horizontâlni zesilovac. Na
obrazovce se objevi stojici elipsa. Odecteme
iiseky Y1 a Y2 a potom fâzovÿ posuv je możno
urcit ze vztahu:
Yi
s i n 9 = Y z —
Mëfeni fâze dvou napëti
If the phase shift between two voltages of like
frequency is to be measured, connect one of
them to the vertical amplifier and the other to
the horizontal one. A stationary ellipse will
appear on the screen. Now read off the length
of the intercepts Y1 and Y2 and determine the
phase shift from the relation
Phase Shift Measurements
Obr. 15 F ig . 15
Pfi
<p
= 0 nebo 180° se elipsa zmeni v pfimku,
pfi
cp —
90° v krużnici. Pro uhly 0— 90° vznikne
elipsa podobna ping vytażene, pro uhly 90° aż
180° carkovane (obr. 15]. Pfi mgfeni delky
usecky Y2 je vyhodne odpojit vstup horizon-
tślniho zesilovace.
Mëreni impedanCniho pfizpûsobeni
Pro rychlé mëfeni impedancniho pfizpûsobeni
je vÿhodnâ metoda vyuzivajici vobler, oscilo-
graf a mërici vedeni (vytvofené üsekem koaxi-
âlniho vedeni). Pfipojime-li na detekcni diodu
oscilograf, na jehoź horizontâlni zesilovaë pfi-
vedeme rozmitaci napëti rozmitaného oscilâ-
toru, kresli paprsek na obrazovce prûbëh sto-
jatÿch vin na vedeni. Jako vedeni poużijeme
pfesnÿ koaxiâlni kabel, jehoż délka je dâna
zdvihem vobleru a poctem vin, které chceme
na obrazovce pozorovat.
1 = _ J ł •150
Af -VI
kde n = pocet vin
A f = zdvih
s = dielektrickâ konstanta kabelu.
Volime-li n = 1, Af = 15 MHz a pohybuje-li se
hodnota dielektrické konstanty pro bóźne ko-
axiâlni kabely kolem 2,5, vyjde nâm délka
1 = 6,32 m.
Pomër maximâlniho a minimâlniho napëti udâ-
vâ pomër stojatÿch vin. Relativni posunuti mi­
nima prübëhu napëti pfi vedeni zatiżenem më-
fenou impedanci vzhledem k minimu napëti pfi
vedeni naprâzdno urcuje ühel odrazu
?.
The ellipse will become a straight line for
v —
0 or 180° and a circle for $> == 90°. The
solid ellipse applies to shift angles from 0 to
90° and the dashed one to angles from 90 to
180° (Fig. 15). When measuring the lenght of
the intercept Y2, it is of advantage to discon­
nect the input of the horizontal amplifier.
Measurements of Impedance Matching
A method suited for fast measurements of im­
pedance matching is one using a wobbler, an
oscilloscope and a measuring line (in the form
of a section of coaxial line). When connecting
the oscilloscope to a detection diode, the wob­
bling voltage of a sweep oscillator being ap­
plied to the horizontal amplifier of the oscil­
loscope, the electron beam depicts on the
screen the stationary waves in the line. A pre­
cision coaxial cable is to be used as the m ea­
suring line, its length being determined by the
frequency deviation of the wobbler and by the
number of waves desired to be observed on
the screen.
I
= n x 150
Af X Ve
where n . . . number of waves
Af . . . frequency deviation
s . . . dielectric constant of the cable.
If the values above are chosen to be n = 1,
Af = 15 MHz, and if the value of the dielectric
constant for currently used coaxial cable is
somewhere about 2.5, the resulting length is
1 = 6.32 m.
The maximum/minimum voltage ratio repre­
sents the stationary wave ratio. The relative
shift of the minimum of the voltage wave with
the line loaded by the impedance being me­
asured in relation to the voltage minimum
with the line free of load determines the angle
of reflection
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