F i g . 6 - 3 1 . T y p i c a l d i s p l a y s w h e n c h e c k i n g o r a d j u s t i n g k H z / D I V
d. Center the IF CENTER FREQ controls and change the
DISPERSION to 50 kHz/div.
e. Apply 10 ns and 10 µs markers from the Time-Mark
Generatar to the RF INPUT.
f. Check-the range of the IF CENTER FREQ-FINE control.
Must equal or exceed 50 kHz either side af center.
g. Center the IF CENTER FREQ controls, change the DIS-
PERSION bock to 500 kHz/div and apply 10 ns and 1 µs
markers,
h.
Check-the dispersion accuracy (Fig. 6-31) at each DIS-
PERSION selector position noted
in Table 6-5.
Measure dispersion accuracy within the center 8 div of the
display for each selector position and over the + and – 2.5
MHz range of the IF center frequency. Check the accuracy
with the IF CENTER FREQ control centered, then rotate the
control to the dial reading noted in step c for 2.5 MHz from
center, and check the dispersion accuracy.
Decrease the sweep speed as the dispersion is decreased,
a n d i n c r e a s e r e s o l u t i o n b y u n c o u p l i n g t h e R E S O L U T I O N
selector. Turn the control counterclockwise to optimize mark-
er definition. Switch the VERTICAL DISPLAY selector to LOG
and the VIDEO FILTER on at these slower sweep rates and
narrow dispersion settings.
i.
T u r n t h e V I D E O F I L T E R t o O F F a n d t h e V E R T I C A L
DISPLAY selector to LIN.
TABLE 6-5
D I S P E R S I O N
T i m e - M a r k G e n e r a t o r
D i v i s i o n s p e r
k H z / D I V
M a r k e r S e l e c t o r
m a r k e r
500
10 ns and 1 µs
2
200
10 ns and 5 µs
1
100
10 ns
and 10 µs
1
50
10 ns
and 10 µ
S
2
20
10
ns and 50 µs
1
10
10 ns and .1 ms
1
5
10 ns and .1 ms
2
10 ns and .5 ms
1
10 ns and .5 ms
6-28
Summary of Contents for 491
Page 4: ...i i Fig 1 1 The Type 491 Spectrum Analyzer ...
Page 24: ...2 16 Fig 2 17 Control set up chart ...
Page 34: ...Fig 3 1 Function block diagram of the Type 491 3 2 ...
Page 42: ...Fig 3 10 Block diagram of the video detector and vertical amplifier 3 1 0 ...
Page 48: ......
Page 53: ...Fig 4 4 Power Supply Circuit board assembly with wiring color code 4 5 ...
Page 54: ...Fig 4 5 Horizontal Display circuit board assembly showing color code to pin connectors 4 6 ...
Page 55: ...Fig 4 6 IF Control board assembly Wiring color code to pin connector 4 7 ...
Page 64: ...Fig 4 20A Tube subassembly removal procedure 4 16 ...
Page 65: ...Fig 4 20B Tube subassembly installation procedure 4 17 ...
Page 68: ...Fig 4 22 Power supply board assembly with component call out 4 2 0 ...
Page 69: ...Fig 4 23 Vertical Amplifier and Blanking board assembly with component call out 4 21 ...
Page 70: ...Fig 4 24 IF control board assembly with component call out 4 22 ...
Page 71: ...Fig 4 24 IF control board assembly with component call out 4 23 ...
Page 72: ...Fig 4 25 Horizontal display board with component call out 4 24 ...
Page 73: ...Fig 4 25 Horizontal display board with component call out 4 25 ...
Page 74: ...Fig 4 26 Phase lock board with component call out 4 26 ...
Page 88: ......
Page 90: ...Fig 6 1 Test equipment recommended for calibration of the Type 491 6 2 ...
Page 138: ......
Page 192: ......
Page 195: ...SECTION II B 3 ...
Page 196: ......
Page 200: ......
Page 201: ...SECTION 9 DIAGRAMS MECHANICAL PARTS LIST ILLUSTRATIONS ACCESSORIES ...
Page 202: ......
Page 203: ...9 1 ...
Page 204: ...9 3 ...
Page 205: ...9 5 ...
Page 206: ...9 7 ...
Page 207: ...9 9 ...
Page 208: ...9 11 ...
Page 209: ...9 13 ...
Page 210: ...9 15 ...
Page 211: ...9 17 ...
Page 212: ...9 19 ...
Page 213: ...9 21 ...
Page 214: ...9 23 ...
Page 215: ...9 25 ...
Page 216: ...9 27 ...
Page 217: ...FIG 1 9 29 ...
Page 218: ...FIG 2 REAR 9 31 ...
Page 219: ...9 33 FIG 3 IF CHASSIS PHASE LOCK ASSEMBLIES ...
Page 220: ...FIG 4 POWER CHASSIS 9 35 ...
Page 221: ...FIG 5 TIME DIV SWITCH OSCILLATOR ASSEMBLIES 9 37 ...
Page 222: ...FIG 6 CRT SHIELD ASSEMBLY 9 39 ...
Page 223: ...FIG 7 CABINET ASSEMBLY HANDLE 9 4 1 ...
Page 224: ...FIG 8 491 STANDARD ACCESSORIES FIG 8 491 STANDARD ACCESSORIES 9 43 ...
Page 225: ......
Page 226: ...PIN 028017 000 ...