HP 11793A Operating And Service Manual page 44

Model 11793A Microwave Converter
13. Disconnect W 2 from S2, port #3, being careful not to bend, crimp, or kink the cable.
14.
15.
Disconnect W3 from S2, port #2, being careful not to bend, Lrimp, or kink the cable.
Disconnect AT1 from S2, port #l.
16.
Remove switches S1 and S 2 from MP14 module base by removing the two screws that secure
each switch.
Unsolder the control wires on each switch (6, 4,
&
92 on SI; 5, 1, & 2 on S2). 17.
18.
Remove the Spira Shield (RF gasket situated in the module base lip) only if damaged, or
necessary for MP 14 module base replacement.
41. RF Module Assembly Procedure for Std, Option 010, & 020 Instruments
1.
2.
3.
4.
5.
6.
Spira Shield (RF gasket) replacement:
Spira Shield
is inserted into a groove in the module base (MP 14). Within the groove a t spaced
intervals, are a series of rectangular protrusions called bosses. Insertion and seaming should begin
and finish at a boss.
a. Use finger protection (such as a rubber finger protector) when working with the Spira Shield.
b. Start at a boss on a straight section of the groove. Push the shielding into the groove using a
protected finger. Guide and twist the shielding to the next boss with the other hand.
c. At the next boss twist the shielding into a tight curl, guide it through the groove, then allow
the shielding to expand to hold itself in place.
d. When an opening in the outer wall of the module is encountered, the shielding should be cut
diagonally. Begin the threading procedure on the other side of the opening.
e. Twist the shielding tighter when rounding corners.
Solder the three control wires to the S2 terminals as follows: green to 1, brown to 2, and red to
C(+).
With the cable slots of the module facing towards the assembler, mount S2 (label up and the
ports pointing to the center of the module) in the left hand side of the module base.
Connect AT 1 to port
#
1 of S 2 .
Connect U 3 to the mixer bracket, ensuring that the mixer side port (which connects to the IF
output) faces opposite to the bracket mounting holes.
Connect U3 to AT1, but do not tighten.
NOTE
Mixer construction varies with manufacturer, and thus, is assembled
within the
RF
Module differently.
For
example, a Norsal mixer has a
sfiffener bar placed between the mixer mounting bracket and the base
mounting castings. An
RHG
mixer has
a
stiffener bar placed above
the mixer mounting bracket.
3 3