Tektronix 492, 492P, Руководство по обслуживанию, Страница: 100 / 303

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c. Adjust the front panel AMPL CAL to its fully ccw posi­
tion and set the Band 1 Gain R2031 (Fig. 3-42) on VR#2
fully ccw.
d. Disconnect P693 from the input to VR#1 module (Fig.
3-44) and apply a 10 MHz, -3 5 dBm signal from the signal
generator through a bnc-to-Sealectro adapter to J693. Ad­
just the generator frequency to peak the signal.
e. Signal amplitude should be between 3.5 and 6.5 divi­
sions. (If signal amplitude is not within these limits it indi­
cates a gain problem in the VR.)
f. If the signal is above 5 divisions, adjust the Post VR
Gain R2038 (Fig. 3-42) for a 5 division signal amplitude (if
the signal amplitude is less than 5 divisions proceed to
part g).
g. Adjust the front panel AMPL CAL for a 7 division
signal.
h. Decrease the generator output to —45 dBm and
change the REF LEVEL to —40 dBm.
i. Adjust the 10 dB Gain R3035 (Fig. 3-44) of VR#1 so
' the signal amplitude is 7 divisions.
j. Change the generator output to —55 dBm and the
REF LEVEL to -5 0 dBm.
k. Adjust the 20 dB Gain R2023 (Fig. 3-44) for a 7 divi
sion signal amplitude.
I. Change the generator output to - 7 5 dBm and the
REF LEVEL to -7 0 dBm.
m. Adjust the 10 dB Gain R2060 (Fig. 3-44) for a 7 divi­
sion signal amplitude.
n. Increase the REF LEVEL to —30 dBm and the gener­
ator output to —35 dBm. Check for a 7 division signal am­
plitude. Repeat this check for —45, —55, —65, and
—75 dBm input levels and note that each maintains the 7
division signal to verify that the gain of the VR gain stages
are correct. Readjust gain if necessary.
REV NOV 1982
Calibration—492/492P Service Vol. 1 (SN B030000 & up)
Adjustment Procedure
A. Response of 10 kHz filte r
B. Response of 100 kHz filte r
2
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2
^
2
B
Fig. 3-45. Typical response o f 10 kHz, 100 kHz and 1 MHz
bandwidth filters.
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