العربيةA poorly terminated connector is the number one cause of signal degradation on an otherwise well-designed RF installation. LMR cables — particularly LMR-400 — are used on VSAT IFL runs, radio base station feedlines, and outdoor antenna installations where the connector is exposed to weather, vibration, and long-term stress. Getting the crimp right the first time saves you a troubleshooting call six months later.
This guide walks through the complete termination process for LMR-400 with an N-type crimp connector — the most common combination in VSAT and radio work — and covers the critical dimensions, tools, and mistakes that separate a reliable termination from a future fault.
LMR-400 Cable Preparation — Strip Stages
LMR-400 N-type crimp | Dimensions per Times Microwave spec | bravosatcom.com
What You’ll Need
Getting the right tools matters more than most people realise. Undersized or worn tooling causes crimp failures that are invisible to the eye but catastrophic for RF performance.
| Tool | Purpose | Notes |
|---|---|---|
| Coax cable cutter | Clean, square cable cut | Never use wire cutters or a hacksaw — both distort the cable end |
| Rotary coax stripper | Strip jacket, braid, dielectric to exact dimensions | Set blade depths for LMR-400 specifically |
| Hex crimp tool + die | Compress ferrule onto braid | LMR-400 N-type typically requires 0.429″ hex die — check connector spec |
| Utility knife / deburring tool | Clean dielectric end, remove stray braid strands | |
| Vernier calipers | Verify strip dimensions | Optional but recommended for critical installs |
| Multimeter | Post-crimp continuity test | Mandatory before putting the cable into service |
Strip Dimensions for LMR-400 N-Type Crimp
These are the published Times Microwave strip dimensions for LMR-400 with a standard N-type crimp connector. Write these on your tool bag if you do this regularly.
| Strip | Dimension | What It Exposes |
|---|---|---|
| Outer jacket removal | 25.4 mm (1.00″) | Braid for fold-back |
| Braid fold-back point | 12.7 mm (0.50″) from jacket end | Positions braid over ferrule |
| Dielectric removal | 12.7 mm (0.50″) from fold point | Centre conductor |
| Centre conductor trim | Flush with connector pin face | Clean mating contact |
Step-by-Step: N-Type Crimp on LMR-400
Common Mistakes
| Mistake | Consequence | Fix |
|---|---|---|
| Forgetting the ferrule before assembly | Must cut off connector and restart | Slide ferrule on as Step 2, every time |
| Nicked centre conductor | PIM, cracking under vibration, future open | Re-cut cable end and re-terminate |
| Stray braid strands on dielectric | Dead short centre-to-outer | Inspect under good light before inserting body |
| Wrong hex die size | Under-crimp — passes pull test, fails in field | Always match die to connector spec sheet |
| Bunched braid fold | Non-uniform crimp, reduced shield coverage | Comb braid evenly around full circumference |
| Centre pin too long | Bottoms out in mating connector, damages both | Trim flush with pin face |
| RG-8 connector on LMR-400 | Wrong bore — mechanically and electrically poor | Always use connectors specified for LMR-400 |
Testing Your Termination
Every terminated connector should pass three checks before the cable goes into service:
Connector Compatibility Quick Reference
Always match the connector spec to your cable. Using an LMR-400 connector on LMR-600 is the most common ordering mistake.
| LMR Cable | Standard Connector | Crimp Die (typical) | Notes |
|---|---|---|---|
| LMR-195 | N-type, SMA, BNC | Per connector spec | Check braid OD matches |
| LMR-240 | N-type, SMA | Per connector spec | |
| LMR-400 | N-type | 0.429″ hex (typical) | Standard VSAT IFL |
| LMR-600 | N-type, 7/16 DIN | Different body | Do NOT mix with LMR-400 connectors |
| LMR-900 | N-type, 7/16 DIN | Large-body only | 7/16 DIN preferred for high power |
For a full cable series comparison, see the Times Microwave LMR Series guide.
FAQ
Can I reuse an LMR connector after removing it?
No. Once a crimp ferrule has been compressed, it cannot be re-used. Cut the connector off, re-prepare the cable end, and use a new connector.
What’s the minimum pull-out force for a properly crimped LMR-400 connector?
Times Microwave specifies approximately 45 kg (100 lbs) minimum pull-out strength for a correctly crimped LMR-400 N-type. If yours pulls off with hand force, the crimp failed.
Can I use a standard N-type connector meant for RG-8 on LMR-400?
No. LMR-400 has a different OD, braid construction, and dielectric. Using an RG-8 connector produces a mechanically and electrically poor termination. Always specify connectors made for LMR-400.
How do I know if my crimp tool die is worn?
A worn die produces ferrules that are out-of-round or show uneven hex faces. Check with calipers — if in doubt, replace the die. A worn die is cheaper to replace than a failed installation.
What’s the difference between silver and gold centre pins?
Silver-plated pins are standard for VSAT work. Gold pins appear in some lower-frequency or high-reliability connectors. For LMR-400 N-type in VSAT IFL work, silver-plated is correct.
Need LMR Cables and Connectors?
Bravo Satcom supplies Times Microwave LMR cables and N-type connectors for VSAT and radio installations across the UAE and GCC. We stock LMR-240, LMR-400, and LMR-600 with matching crimp and compression connectors.