7-18 Replacing VNA PCB Assembly Assembly Removal and Replacement, MS203xC
7-42 PN: 10580-00307 Rev. D MS20xxC MM
Removing Coaxial Cables:
9. Using needle-nose pliers, remove the 4 attached coaxial cables from the Main PCB Assembly and the SPA
PCB at the following locations. All 4 cables connect to locations on the VNA PCB Assembly. Leave the
cables attached to the VNA PCB Assembly until you are ready for the replacement VNA Assembly.
a. From Mother Board (Main PCB Assembly):
• J2201 26 MHz Out – Cable connected to the top RF shield on the VNA Module.
(MCX connectors)
• J3202 Trig In – Cable connected to the Ext Trig In BNC connector on the top connector
panel of the VNA PCB Assembly and an MMCX connector on the Mother Board. Refer to
Figure 7-19 on page 7-39 for coaxial cable connections between the VNA PCB Assembly and
the Main PCB Assembly.
b. From SPA PCB:
Cut the cable tie near the fan (if used) that holds the 4 RF cables that connect the case front to the
case back.
• J6000 (Ext Ref) – Cable connected to the Ext Ref In BNC connector on the VNA PCB
Assembly and an MMCX connector on the SPA PCB.
• J6001 (10 MHz Ref Out) – Cable connected to the Ref Out 10 MHz SMA connector on the top
connector panel and an MMCX connector on the SPA PCB.
10. Remove the VNA PCB Assembly (with cables attached) and set it aside.
Preparing the Replacement VNA Assembly:
11. Prepare the replacement VNA PCB Assembly by transferring cables.
a. Using needle-nose pliers, remove the 26 MHz VNA Reference cable from the older VNA PCB
Assembly. Attach one end to the MCX connector (J7002) on the top shield of the VNA Module.
b. Using the Tool T1451 socket, remove the castellated BNC dress nut from the Ext Trig In BNC
connector from the older VNA PCB Assembly.
Attach the BNC connector in the top Connector panel of the replacement VNA Assembly. Use the
Tool T1451 socket to tighten the BNC Connector Dress Nut. The torque specification is 7.5 lbf·in
(0.85 N·m).
c. Using the Tool T1451 socket, remove the castellated BNC dress nut from the Ext Ref In BNC
connector from the older VNA PCB Assembly.
Attach the BNC connector in the top connector panel of the replacement VNA Assembly. Use the
Tool T1451 socket to tighten the BNC Connector Dress Nut. The torque specification is 7.5 lbf·in
(0.85 N·m).
d. Use two 5/16 inch (≅ 8 mm) wrenches to disconnect the Ref Out 10 MHz SMA connector from the
top connector panel of the older VNA PCB Assembly.
Use the two 5/16 inch (~8 mm) wrenches to attach the SMA connector to the new connector panel.
Torque the nut to 7.5 lbf·in (0.85 N·m).
12. If your instrument is equipped with the GPS Receiver Module (Option 31), then remove the hole plug for
the GPS Antenna from the top connector panel.
Installing the Replacement VNA Assembly:
For cable routing and connections, refer to Figure 7-19 on page 7-39 and Figure 7-21 on page 7-41.
13. Position the replacement VNA Assembly on top of, and offset from, the Main PCB Assembly (Mother
Board) such that the MCX and MMCX connectors along the lower edge of the Mother Board are exposed
for easy cable attachment. Refer to Figure 7-5 on page 7-7 and Figure 7-7 on page 7-9 for general
orientation.
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