Fig. 6-15. Location of trigger and sweep adjustments.
c. Preset the Sweep Cal R787 to midrange. Adjust the
Sweep Gain R813 (see Fig. 6-15) for 10.5 divisions of sweep
length. Adjust Sweep Cal R787 for 1 marker per division.
S w e e p t i m i n g m u s t b e w i t h i n ± 3 % ( 1 . 2 m i n o r d i v i s i o n s )
over the center 8 graticule divisions.
T A B L E 6 - 3
14. Check Sweep Timing Accuracy
a. Equipment setup is given in step 13.
b. With the Marker Output signal from the Time-Mark
Generator applied to pin H of the Vertical Amplifier circuit
board, adjust the LEVEL control for a stable triggered trace.
Position the zero timing mark and the start of the trace on
the left graticule line.
c. Check timing accuracy (±3%) at each position of the
TIME/DIV selector. Marker input and Type 491 display for
each position is listed in Table 6-3.
15. Check VARIABLE Control Range
a. Equipment setup is given in step 14
b. Apply 5 ms markers to pin H of the Vertical Amplifier
circuit board assembly. Set the Type 491 TIME/DIV selector
to 1 ms and adjust the Triggering LEVEL control for a stable
display. One 5 ms marker/5 divisions.)
c. Turn the VARIABLE control fully counterclockwise.
d. Check-A minimum of five markers should be displayed
within the 10 division graticule width. Variable control range
2.5:1.
16. Check SAW OUT Signal Amplitude
a. Equipment setup is given in step 12.
b. Connect the
1×
probe from the test oscilloscope to
the SAW OUT connector on the rear panel of the Type 491.
F i g . 6 - 1 6 . S a w t o o t h w a v e f o r m a n d b l a n k i n g w a v e f o r m .
6 - 1 8
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 ...