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Fig. 6-33. Adjusting avalanche voltage.
just below the state of free running avalanche. Free running
avalanche, appears as an RF burst signal between the 1 MHz
pulses as shown in Fig. 6-33C; or with the INT REF FREQ
control in the OFF position, the free running avalanche
transistor signal will feed through to the 1 MHz MARKERS
OUT connector, and appear on the test oscilloscope as a
2 MHz burst. If free running avalanche does not occur, turn
the adjustment fully clockwise.
F i g . 6 - 3 4 . L o c a t i o n o f L 1 1 0 4 a n d 1 1 1 0 8 , R 1 1 5 0 a n d R 1 1 4 0 .
e. Switch the band selector to band C. Turn the INT REF
FREQ control on.
f. Push the LOCK CHECK button. Check for beat signal
displays as the FINE RF CENTER FREQ control is rotated
through its range.
27. Adjust 1 MHz REF FREQ Range
o
a. Equipment set up is given in step 26.
b . A p p l y t h e o u t p u t f r o m t h e 1 M H z M A R K E R S O U T
signal through a
10×
attenuator to J120 on the honeycomb
assembly as follows: Connect a GR to Sealectro adapter
(such as a P6040 probe cable), a GR to BNC adapter and a
20 dB attenuator, (see Fig. 6-32) between the 1 MHz MARK-
ERS OUT connector and J120. Disconnect the Sealectro
connector from J120.
c. Set the DISPERSION to 100 kHz/Div and position a
1 MHz marker to the screen center with the IF CENTER
FREQ control.
d. Adjust L1108 (Fig. 6-34) for a positive oscillator start
when the INT REF FREQ control is turned from its OFF to
ON position. The signal position on the screen should be
consistent as the INT REF FREQ control is switched from
OFF to the initial ON position. (The control must not be
turned past the initial ON position or the oscillator frequency
will be changed.]
e. Rotate the INT REF FREQ control through its range
Check the total frequency shift of the internal reference
1 MHz marker.
6-30
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 ...