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Jump to: Connector
Interfaces | Cable
Routing | Cable
Assembly Mate/De-Mate Process
Connector
Interfaces:
Interface Cleanliness
- Clean Interfaces prolong connector life
and produce more accurate, repeatable measurements.
The use of connector end-caps to protect test cables
and adapters when not in use is recommended.
Interface Cleaning
Procedure:
1. Solvents: Connector Insulators, support beads, and
seals are susceptible to solvent damage. Solvents can
produce permanent physical and electrical damage. Isopropyl
Alcohol is recommended for cleaning interfaces. It
should be noted that connector interfaces should not
be immersed in solvents of any kind because solvents
can become trapped within the connectorized assembly.
Trapped fluids can cause SWR, Phase, and Insertion
Loss problems.
2. Applicators: Fibrous or Abrasive applicators can
contaminate and even damage interface surfaces. Clean
lint free swabs should be used. They need to be sharp
enough and hard enough to remove dirt and debris without
damaging surfaces and/or dislodging center pins.
3. Method: Dip a clean lint free swab in clean isopropyl
alcohol. Press excess alcohol out of swab on a clean
lint free towel. Wipe the interface components as required
to clean the interface. Blow-dry the interface with
clean compressed air. Re-inspect the connector to verify
that the interface is clean and ready for additional
inspection procedures and interface gauging prior to
use.
Interface Gauging
- Incorrect center pin depths can produce
inaccurate measurements and in the case of protruding
center pins can damage test devices, adapters, and
test ports. Frequent interface gauging can detect gauging
problems before they ruin mating devices (see Table
I for connector interface pin depths).
| Table
I: Connector Interface Pin Depths |
| Connector
Interface |
Contact
Location wrt Reference Plane (in) |
Specification |
| 7mm |
-0.002/-0.002 |
IEEE
STD 287 |
| N
Male |
0.210/-0.230 |
MIL-STD-348 |
| N
Female |
+0.187/+0.207 |
MIL-STD-348 |
| 3.5mm |
0/-0.003 |
IEEE
STD 287 |
| 2.92mm |
0/-0.003 |
IEEE
STD 287 |
| 2.4mm |
0/-0.002 |
IEEE
STD 287 |
| 1.85mm |
0/-0.002 |
IEEE
STD 287 |
| SMA |
0/-0.010 |
MIL-STD-348 |
| TNC
/ BNC |
-0.210/-0.230 |
MIL-STD-348 |
| TNC
/ BNC |
+0.186/+0.206 |
MIL-STD-348 |
| 7-16
Male |
+0.0579/+0.0697 |
IEC
169-4 |
| 7-16
Female |
-0.0697/-0.0815 |
IEC
169-4 |
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Recommended Coupling
Torque - Incorrect coupling torque can produce
inaccurate measurements and over-torque coupling can
damage test devices, adapters, and test ports. Torque
wrenches should be utilized to for all Mate/De-Mate processes
(see Table II for recommended coupling torque values).
| Table
II: Recommended Coupling Torque |
| Interface
Type |
Coupling
Torque |
| 7mm,
N |
12
in-lbs |
| 3.5mm,
2.92mm, K®, 2.4mm, 1.85mm |
8
in-lbs |
| SMA,
TNC |
5
in-lbs |
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Cable
Routing:
Bend Radius - Care
should be taken to avoid over-bending test cables beyond
minimum bend radius guidelines. Over-bending can force
cable center conductor off-center, and can force the
outer conductor out of round even to the point of kinking
and fracture. Over bending results in degraded IL and
SWR performance. It should also be noted that coiling
cables at small diameters could force connector center-pins
to protrude beyond required interface dimensions.
Twisting - Twisting
test cables should be avoided at all times. Excessive
twist can damage cable assembly at the cable/connector
junction or even mid-cable depending on how the twist
is applied. Lower level twist can cause measurement problems
as well. Induced stresses on test ports and device ports
can damage the ports. Low level stresses can cause connections
to loosen up.
Cable
Assembly Mate/De-Mate Process:
Interface Alignment
- Contact Pins and Dielectrics can be damaged
if misaligned connectors are mated. Make sure that mating
interfaces are parallel and on center during Mate/De-Mate
cycle
Interface Rotation
- Plating and surface finish of outer and
inner contacts can be damaged it connector bodies are
allowed to rotate during Mate/De-Mate cycle. Use wrench
flats on connector bodies to keep them rotationally stationary
while rotating coupling nut during mate/de-mate.
Minimized Load
Configuration - Allow test cable to assume
natural bend configuration route between test port and
device port. Loosen test port connection when test configuration
is largely different than test configuration. Route the
cable, connect device port loosely then tighten both
port connections to recommended coupling torque (see
Table II above). This method will minimize most bend
and twist loading issues.
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