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Fig. 6-22. Dispersion calibration adjustments.
d . A d j u s t t h e D I S P E R S I O N C A L R 2 0 8 ( F i g . 6 - 2 2 ) f o r 1
marker/division over the center 8 graticule divisions, then
adjust C358 for display linearity.
e. Repeat the adjustment of R208 and C358 for optimum
dispersion accuracy and display linearity. If the dispersion
linearity is not within tolerance, a slight re-adjustment of
the RF Ampl R290 and the Center Freq Range R251 adjust-
ments may be required. Monitor the voltage at pin P of the
honeycomb square pin connector with the test oscilloscope
to keep the RF voltage amplitude within 0.75 to 1.0 volts and
recheck step 18.
22.
a.
b.
c.
Check Dispersion Accuracy of MHz/DIV
Ranges and Range of IF CENTER FREQ
Control
Test equipment setup is given in step 21.
Center the IF CENTER FREQ controls.
C h e c k t h e d i s p e r s i o n a c c u r a c y f o r e a c h M H z / D I V
setting of the DISPERSION selector as listed in Table 6-4.
The Horizontal POSITION central, or the IF CENTER FREQ
control may be used to align the prime markers to the
graticule divisions.
As the DISPERSION is decreased, the
RESOLUTION control should remain in the coupled posi-
tion.
d. Check the range of the IF CENTER FREQ control plus
the dispersion accuracy and linearity over this range, in
the 5, 2, 1, .5 and .2 MHz positions of the DISPERSION selec-
tor.
Range of the coarse control should equal or
and - 25 MHz from its centered position.
It is checked
by rotating the control to both extreme positions from cen-
ter and noting the frequency shift of the .1 µs or 10 MHz
markers as the control is rotated. Dispersion accuracy and
display linearity must remain within the listed specifications
of Table 6-4 to the + and - 25 MHz positions.
e. Center the coarse IF CENTER FREQ control. Set the
DISPERSION control to 1 MHz position and apply 10 ns and
1 µs markers from the Time-Mark Generator.
f . C h e c k - T h e r a n g e o f t h e I F C E N T E R F R E Q - F I N E c o n -
trol. Must equal or and - 1 MHz from its cen-
tered position.
TABLE 6-4
6-22
Содержание 491
Страница 4: ...i i Fig 1 1 The Type 491 Spectrum Analyzer ...
Страница 24: ...2 16 Fig 2 17 Control set up chart ...
Страница 34: ...Fig 3 1 Function block diagram of the Type 491 3 2 ...
Страница 42: ...Fig 3 10 Block diagram of the video detector and vertical amplifier 3 1 0 ...
Страница 48: ......
Страница 53: ...Fig 4 4 Power Supply Circuit board assembly with wiring color code 4 5 ...
Страница 54: ...Fig 4 5 Horizontal Display circuit board assembly showing color code to pin connectors 4 6 ...
Страница 55: ...Fig 4 6 IF Control board assembly Wiring color code to pin connector 4 7 ...
Страница 64: ...Fig 4 20A Tube subassembly removal procedure 4 16 ...
Страница 65: ...Fig 4 20B Tube subassembly installation procedure 4 17 ...
Страница 68: ...Fig 4 22 Power supply board assembly with component call out 4 2 0 ...
Страница 69: ...Fig 4 23 Vertical Amplifier and Blanking board assembly with component call out 4 21 ...
Страница 70: ...Fig 4 24 IF control board assembly with component call out 4 22 ...
Страница 71: ...Fig 4 24 IF control board assembly with component call out 4 23 ...
Страница 72: ...Fig 4 25 Horizontal display board with component call out 4 24 ...
Страница 73: ...Fig 4 25 Horizontal display board with component call out 4 25 ...
Страница 74: ...Fig 4 26 Phase lock board with component call out 4 26 ...
Страница 88: ......
Страница 90: ...Fig 6 1 Test equipment recommended for calibration of the Type 491 6 2 ...
Страница 91: ...Fig 6 2 Test equipment recommended to measure the dial accuracy receiver sensitivity and response flatness 6 3 ...
Страница 138: ......
Страница 191: ...APPENDIX A BASIC ISSUE ITEMS LIST Basic issue items list will be published at a later date A 1 ...
Страница 192: ......
Страница 195: ...SECTION II B 3 ...
Страница 196: ......
Страница 200: ......
Страница 201: ...SECTION 9 DIAGRAMS MECHANICAL PARTS LIST ILLUSTRATIONS ACCESSORIES ...
Страница 202: ......
Страница 203: ...9 1 ...
Страница 204: ...9 3 ...
Страница 205: ...9 5 ...
Страница 206: ...9 7 ...
Страница 207: ...9 9 ...
Страница 208: ...9 11 ...
Страница 209: ...9 13 ...
Страница 210: ...9 15 ...
Страница 211: ...9 17 ...
Страница 212: ...9 19 ...
Страница 213: ...9 21 ...
Страница 214: ...9 23 ...
Страница 215: ...9 25 ...
Страница 216: ...9 27 ...
Страница 217: ...FIG 1 9 29 ...
Страница 218: ...FIG 2 REAR 9 31 ...
Страница 219: ...9 33 FIG 3 IF CHASSIS PHASE LOCK ASSEMBLIES ...
Страница 220: ...FIG 4 POWER CHASSIS 9 35 ...
Страница 221: ...FIG 5 TIME DIV SWITCH OSCILLATOR ASSEMBLIES 9 37 ...
Страница 222: ...FIG 6 CRT SHIELD ASSEMBLY 9 39 ...
Страница 223: ...FIG 7 CABINET ASSEMBLY HANDLE 9 4 1 ...
Страница 224: ...FIG 8 491 STANDARD ACCESSORIES FIG 8 491 STANDARD ACCESSORIES 9 43 ...
Страница 225: ......
Страница 226: ...PIN 028017 000 ...