737-300 400 500 AMM 飞机维护手册 STANDARD PRACTICES(78)

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 C.  The TDR has displays to help you. Push the MENU button to get access to these displays. To get out of the MENU function, continue to push MENU until it goes back to the "Normal Operation" mode.
 D.  The TDR can be operated from a 115-volt ac or 230-volt ac (45 to 440Hz) power source or an optional internal battery pack. A minimum of 5 hours of operation time is available from the battery pack if it is fully charged.
 E.  To do a check of a cable, you must disconnect the cable at each end. Connect the TDR to one end of the cable. Adapter cables to connect the TDR to the cable must be assembled locally. Use the applicable system wiring diagram to help isolate the failure to a specified connector, cable segment or black box.
 F.  To find the distance in feet from one end of the cable to a failure, move the cursor on the LCD to the first impedance change. You will see the distance to the failure in the top right corner of the LCD.
 G.  Refer to the Tektronix Operators Manual, part number 070-6266-00 for more data.
 TASK 20-10-72-212-010
 2.  Coaxial Cable Inspection________________________
 A.  General
 (1)  The TDR front panel has these controls:
 (a)  
NOISE FILTER - uses noise-averaging to decrease the quantity of noise on the waveform.

 (b)  
VERT SCALE - sets the vertical sensitivity (millirho per division) or vertical gain (dB).

 (c)  
DIST/DIV - sets the number of feet (meters) for each division across the LCD.

 (d)  
Vp - velocity of propagation. You set these controls to the propagation velocity value of the cable.

 (e)  
POWER - pull for power on, push for power off.

 (f)  
POSITION - moves the waveform up or down on the LCD.

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 20-10-72
 ALL  ú ú 01 Page 201 ú Nov 12/01
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 (2)
(3)

(4)

(5)

A
737-300/400/500MAINTENANCE MANUAL
 (g)  
POSITION - moves the vertical cursor across the LCD. The waveform is also moved when the cursor gets to the far right or left side of the LCD.

 (h)  
MENU - gives access to the menu.

 (i)  
VIEW INPUT - permits you to view or remove the waveform shown on the LCD.

 (j)  
VIEW STORE - shows the waveform that is kept in memory.

 (k)  
VIEW DIFF - shows the result of the waveform shown minus the waveform in memory.

 (l)
STORE - puts the waveform into memory.
Vp is the speed of a signal down the cable. This value is different
 for different types of cables. If you do not know the Vp, refer to
 Table 1 for approximate values.

 

 NOTE: If the Vp is set incorrectly, the failure will show
____ but the distance will possibly not be accurate.
 ~..................................................
 | TABLE 1 |
 ....................................................
 | TYPE OF CABLE | PROBABLE Vp |
 ....................................................
 | Jelly Filled | .64 |
 ....................................................
 | Polyethylene (PIC, PE, or SPE) | .66 |
 ....................................................
 | PTFE (Teflon) or TFE | .70 |
 ....................................................
 | Pulp Insulation | .72 |
 ....................................................
 | Foam or Cellular PE (FPE) | .78 |
 ....................................................
 | Semi.solid PE (SSPE) | .84 |
 ....................................................
 | Air (Helical spacers) | .98 |
 2..................................…...............1

Bleed a cable before you attach it to the TDR to remove static from
 the cable. You can use a 50 ohm terminator and a BNC adapter to
 bleed a cable.
You will always see a rising pulse at the start of the waveform.
 This is the test pulse from the TDR.
During this procedure the cable that you do a check of will be
 referred to as the applicable cable.

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