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Page 6
list in back of manual.) Include the following in¬
formation for each part: model number, Hewlett-
Packard part number, and description.
42. SERVICE
43. The succeeding paragraphs give instructions
for repair of the Model 423A and 8470A Crystal
Detectors and the Option 002 Load Resistor,
Model 11523A. Additional maintenance informa¬
tion can be obtained from the local Hewlett-Packard
office. Part numbers for replaceable parts are given
in Table 2.
44. Detector Element Replacement
45. The detector element assembly includes only
a detector element, unless an Option 002 is ordered,
then a replacement load resistor for the 11523A is
included. The resistor is to load the diode for square-
law operation.
The special detector element (see Figure 4)
contained in the detector can be damaged
in handling
,
removal, or installation if cer¬
tain precautions are not taken. Then hand¬
ling precautions which follow should be
read before performance of any operation
with the detector element when it is out
of either the housing or the detector ele¬
ment shipping container.
a.
Before installing diode into mount, touch
exposed metal on mount with your hand to dis¬
charge static electricity. Then insert diode into
mount.
b.
When handing diode to another person,
touch hands first to ensure there is no difference in
static electricity potential between you.
c.
Ohmmeters should not be used to meas¬
ure forward- and back-resistance since it is easy to
damage these diodes. The difficulty arises because
of the ohmmeter's open-circuit voltages and short-
circuit currents.
40. Replacing Detector Element
47. Parts mentioned in the following procedure
are identified in Figure 4.
a. Remove connector cap from body. To
Model 423A/8470A
remove connector cap, use a pair of gas pliers with
plastic teeth or protect body with heavy paper or
tape.
b.
Remove old detector element, capsule
spacer, and capacitive washer, and discard them.
c.
Install the new capacitivie washer, capsule
spacer, and detector element. Install the washer
first, the spacer with its polyiron side against the
washer. Finally, install the detector element by
inserting the resistive end into the center contact
inside the detector body.
| CAUTION 1
When inserting the detector element
,
do
not force the tip (resistive end) into the
center conductor in the body as the fin¬
gers of the center conductor might be
damaged
,
if the detector element is not
centered.
d. Replace connector cap and TIGHTEN
FIRMLY.
NOTE
The Option 002 Detector Element Assem¬
bly includes a detector element and a re¬
sistor. The resistor is for use in the Model
11523A and must be installed to match it
to the detector.
48. Replacement of Load Resistor (11523A) Parts
49. Parts mentioned in the following procedure are
identified in Figures 2 and 3.
50. Replacing Male RNC Connector
a.
Remove male BNC connector and lock
washer from housing. To remove BNC connector,
use a 3/8-inch open-end wrench and hold the hous¬
ing either in a vise or with pliers. Before using the
vise or pliers, protect the housing of the 11523A
with material such as heavy paper or tape or use
plastic jaws on the vise or pliers.
b.
Unsolder resistor.
,
c. Solder resistor to new BNC connector.
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