Filter
Top Products
Performance Verification
4–24
1780R-Series Service Manual
k. Check set the generator to each of the following frequencies: 3.58 MHz
(4.43 MHz for PAL), 5 MHz, 8 MHz, and 10 MHz. Use parts i. and j. as
a guide for checking the frequency response at each given frequency.
l. Set the generator frequency to 15 MHz. Set the generator output
amplitude to obtain the same DMM reading as noted in part g. of this
step.
m. Check that the signal amplitude displayed on the Waveform CRT is
714 mV or 100 IRE in amplitude within +14.3 mV and –35.5 mV for
NTSC (700 mV within +14.0 mV and –35.0 mV for PAL).
n. Set the generator frequency to 20 MHz. Set the generator output
amplitude to obtain the same DMM reading as noted in part g. of this
step.
o. Check that the signal amplitude displayed on the Waveform CRT is
714 mV or 100 IRE in amplitude within +14.3 mV and –107.5 mV for
NTSC (700 mV within 14.0 mV and –105 mV for PAL).
p. Disconnect the sine wave signal and Peak-to-Peak Detector Head from
the CH A INPUT connector.
12. Check X1 Gain CH B1 Frequency Response
Requirement: Flat frequency response from 50 kHz to 5 MHz within 1%.
50 kHz is used as a reference. Flat frequency response from 5 MHz to
10 MHz within ±2% of the reference amplitude. 10 MHz to 15 MHz should
be within +2% and –5% of the reference amplitude. 15 MHz to 20 MHz
should be within +2% and –15% of the reference amplitude.
a. Connect the leveled sine wave generator output, through a 50 W-to-75 W
minimum loss attenuator, to the CH B1 INPUT connector. Do not
terminate the loop-through connector.
b. Select INPUT–CH B1.
c. Check repeat step 11b. through 11p. to check the frequency response of
the 1780R-Series CH B1 INPUT. Parts b., e., and p. should read “CH B1
INPUT” when using the step 11 procedure as a guide. Also, part j.
should read ±14.3 mV for NTSC (±14.0 mV for PAL) when checking
these frequencies: 8 MHz and 10 MHz.
13. Check X1 Gain CH B2 Frequency Response
Requirement: Flat frequency response from 50 kHz to 5 MHz within 1%.
50 kHz is used as a reference. Flat frequency response from 5 MHz to
10 MHz within ±2% of the reference amplitude. 10 MHz to 15 MHz should
be within +2% and –5% of the reference amplitude. 15 MHz to 20 MHz
should be within +2% and –15% of the reference amplitude.