Backdating
7-42
Model 3585A
Table 8·A·3·6. Crystal and Padding Resistor Numbers
Crystal
Padding Resistor
Y 1
A 1 1 R 9 6
Y2
A 1 1 R97
Y3
A 1 2 R 5 2
Y4
A 1 3R84
Y5
A 1 3R86
f.
Once the new set of crystals are installed they must be adjusted in the manner
outlined in Paragraph 5-9 Volume 2.
NOTE
If the symmetry adjustment on one of the individual stages does
not have enough range, execute the following procedure.
1. Attempt to adjust the symmetry. Leave the symmetry ad
justing capacitor in the position which gives the best symmetry.
2. If the plates of the symmetry capacitor are fully meshed,
choose a larger capacitor from the padding list. If the plates of the
symmetry capacitor are fully unmeshed, choose a smaller value
capacitor from the padding list (see Table 8-A -3-7 for symmetry
capacitor padding lists).
Table 8·A·3·7. Symmetry Capactor Padding List
Board Number
Component Number
Component Value
·hp· Part Number
A 1 1
C 7 0 *
3 . 9pF
0 1 60- 2 2 4 7
5 . 1 p F
0 1 60- 2 2 50
A 1 1
C 7 1 *
5 . 1 pF
0 1 60- 2 2 5 0
6 . 2 pF
0 1 60- 2 2 5 2
7 . 5pF
0 1 60- 2 2 54
A 1 2
C83 *
3 . 9pF
0 1 60- 2 2 4 7
5 . 1 p F
0 1 60- 2 2 50
A 1 3
C66 * ,C67 *
3 . 9 pF
0 1 60- 2 2 4 7
5 . 1 p F
0 1 60- 2 2 50
g.
After adjusting the IF Filters, check the 3dB Bandwidth and Shape Factor of each
Resolution BW.
1 . If the 3dB Banddwidth and Shape Factor are within spec (3dB Bandwidth
=
Resolution Bandwidth ± 20%, Shape Factor
=
60dB BW/3dB BW
s
1 1 : 1 )
then you have successfully installed a new set o f IF crystals .
2.
If the 3dB Bandwidth or Shape Factor is out of spec, then the width of some
of the filter stages may need to be changed . Generally, the bandwidth will be
too wide if there is
a
problem.
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