Tektronix 1730 Series, Инструкция по эксплуатации

Страница: 140 / 258

1730–Series Checks and Adjustments
5–24
e. CHECK – that the amplitude of the linearity signal, in LPASS, is within
±
1% of the amplitude of the display in the FLAT mode.
18. Check Chroma Filter Response
REQUIREMENT – Response at 3.58 MHz (4.43 MHz for PAL) does not vary
between FLAT and CHROMA by more than 1%. Attenuation at 7.2 MHz
(8.9 MHz for PAL): greater than 20 dB.
a. Connect the color bar signal to the CH–B INPUT and terminate the
remaining side of the loop–through input.
b. Turn the Luminance (Y) portion of the signal off. Unlock the SCH
phasing of the generator.
c. Display the signal in FLAT with the 2LINE SWEEP and INT REF. Use
the 1730–Series VARIABLE gain control to adjust the amplitude of the
largest Chroma packet to equal the amplitude from blanking to 100%
peak white. Switch the FILTER to CHROMA.
d. CHECK – that the amplitude of the largest chrominance bar is 99 to
101% of the amplitude in part b.
e. Select FLAT filter. Connect the sine wave generator to the CH–B
INPUT and set the frequency to 50 kHz. Adjust the amplitude so that
the display is 100 IRE (700 mV for PAL).
f. Set the frequency of the sine wave generator to 7.2 MHz (8.9 MHz for
PAL). Select CHROMA filter.
g. CHECK – that less than 10% of the reference amplitude remains.
19. Check Return Loss
REQUIREMENT – Return Loss for INPUT at least 40 dB from 50 kHz to
6 MHz (instrument on or off, any deflection factor setting). Return Loss of the
PIX MON OUT at least 30 dB (50 kHz to 6 MHz) with the instrument on.
NOTE
. Return Loss Check:
The Return Loss Check needs to be done only if repairs have been made on the
Input circuitry.
a. Connect a precision 50
W
cable from the spectrum analyzer RF Input to
the RF Output on the RF Bridge.
b. Connect a precision 50
W
cable from the spectrum analyzer TG Output to
the RF Input on the RF Bridge.