Cable

How to Crimp LMR Connectors Correctly: Step-by-Step Guide

Posted on July 7, 2026July 7, 2026 by rai

A 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

Jacket

Full length

Braid exposed

25.4 mm

(fold back)

Dielectric

12.7 mm

(stripped)

Centre pin

12.7 mm

exposed

Outer jacket (PE)

Braid + foil shield

Foam PE dielectric

Copper centre conductor

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

Connector types: This guide covers crimp connectors — the most common in field work. Times Microwave also makes EZ-400 compression connectors (faster, single-action, requires the matching tool) and solder-type connectors. The cable prep dimensions are similar but confirm against your specific connector’s installation sheet.

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

Dimensions vary between connector manufacturers. Always cross-check against your specific connector’s installation sheet before terminating.

Step-by-Step: N-Type Crimp on LMR-400

Cut the cable square. Use a proper coax cutter. The cut must be clean, flat, and perpendicular. Inspect: jacket, braid, dielectric, and centre conductor must all be concentric and undamaged. Any burr or angle — cut again.

Slide on the crimp ferrule first. Before stripping anything, slide the crimp ferrule (small metal ring) onto the cable with the open end facing the cable end. This is the most commonly forgotten step. You cannot install it after the connector body is on.

Strip the outer jacket — 25.4 mm. Set your rotary stripper and rotate 2–3 times, then pull the jacket off cleanly. Inspect the braid — intact, no nicks, no cut strands. Remove any cut braid strands before proceeding.

Fold back the braid — at 12.7 mm. Comb the braid wires back evenly over the outer jacket. Spread uniformly around the full circumference — avoid bunching. Bunched braid concentrates crimp force on one side and reduces shield effectiveness.

Strip the dielectric — 12.7 mm. Remove foam dielectric to expose the centre conductor. The cut must be clean — no gouges or teeth marks on the copper. Even minor nicks increase PIM and create stress crack points under vibration.

Inspect before assembly. Blow out loose strands. Verify strip dimensions. Confirm no braid strands are on the dielectric. Check the centre conductor is round and undamaged. A 30-second inspection here prevents a re-termination in the field.

Install the connector body. Slide the connector body onto the cable. The centre conductor passes through the contact pin and protrudes slightly — trim flush with the pin face. The braid seats inside the connector’s braid seat area. Push fully home until it seats firmly.

Slide the ferrule into position. Slide the crimp ferrule forward until it butts against the rear of the connector body, sitting over the folded braid.

Crimp. Place the ferrule in the correct hex die. Close the handles with a single smooth, firm stroke until the ratchet releases. One complete ratchet cycle only — do not over-crimp (distorts the body) or under-crimp (ferrule slips).

Inspect the finished crimp. The ferrule should be uniformly hexagonal, no cracking or oval distortion. Firm tug — connector should not move. No braid strands protruding. Centre pin flush or just proud of the mating face.

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:

① Visual Inspection

Ferrule uniformly hexagonal. No braid strands protruding. Centre pin flush. Connector firmly seated — no movement under hand tug.

② DC Continuity (Multimeter)

Centre pin to centre pin: continuity. Centre pin to outer body: open circuit. Any short = failed termination, re-terminate.

③ Return Loss / VSWR (if available)

Good LMR-400 termination: >25 dB return loss (VSWR <1.12:1) at 1 GHz. Worse than 20 dB (VSWR >1.22:1) indicates a problem.

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.

→ Browse cable products → Request a quote

Uncategorized

Fiber Optic vs Coaxial Cable: When to Use Each

Posted on July 4, 2026July 4, 2026 by admin

Every RF and satellite engineer hits this fork eventually: you’re designing a cable run and someone asks, “should we go fiber?” The right answer depends almost entirely on what the cable is carrying. If it’s connecting a modem to a BUC or LNB, the answer is always coaxial — no exceptions. If it’s a data backbone between buildings, fiber is almost certainly the better call.

This guide breaks down the key differences between fiber optic and coaxial cable and gives you a clear framework for choosing the right one every time.

Fig 1. Cable cross-section comparison: coaxial (LMR-400) vs single-mode fiber optic (SMF OS2). The critical difference for VSAT installations — coaxial cable carries DC power to the BUC and LNB alongside the RF signal; fiber cannot.

What Is Coaxial Cable?

Coaxial cable carries RF signals as electrical waves along a center copper conductor, insulated from a surrounding braid or foil shield by a dielectric foam core. The shield keeps the signal contained and blocks external interference from entering. An outer PE or PVC jacket provides mechanical and weather protection.

In VSAT and satellite applications the most common types are LMR-400 (standard Ku-band IFL, runs to ~30m), LMR-600 (medium runs to ~60m), LMR-900 (long runs to 80m+), and legacy RG214. For broadcast and CATV distribution, 75Ω RG6 is common.

The capability that makes coaxial indispensable for satellite work: it carries DC power alongside the RF signal. The same cable that carries your IF signal from modem to LNB also delivers the 13V or 18V DC that powers the LNB — plus the 22 kHz polarisation tone — and the 24–48V DC that drives the BUC. No other single cable can do this.

What Is Fiber Optic Cable?

Fiber optic cable carries signals as pulses of light through a glass core, surrounded by cladding (a lower-refractive-index glass layer that traps light inside by total internal reflection), a protective buffer coating, and an outer jacket. There are no copper conductors — signals travel at the speed of light with virtually no attenuation over distance.

Two main types exist: single-mode fiber (SMF, OS1/OS2) for long-distance runs up to 40+ km, and multi-mode fiber (MMF, OM3/OM4) for shorter data links up to ~300m. For telecom and data center backbone, SMF OS2 is the current standard.

The defining advantages: attenuation of just 0.2 dB/km at 1550 nm (vs approximately 30 dB/100m for LMR-400 at Ku-band), complete immunity to electromagnetic interference, and effectively unlimited bandwidth. The defining limitation: fiber cannot carry DC power. Any powered equipment at the far end requires a separate power cable.

Fiber Optic vs Coaxial Cable: Full Comparison

Feature	Coaxial Cable (LMR-400)	Fiber Optic (SMF OS2)
Signal medium	Electrical (RF waves)	Light (photons)
Attenuation @ 1 GHz	6.8 dB / 100m	0.035 dB / 100m
Attenuation @ Ku-band (12 GHz)	~30 dB / 100m	N/A — light, not RF
Max practical IFL run (Ku-band)	30m (LMR-400) · 60m (LMR-600) · 80m (LMR-900)	Not suitable for IFL
Max data run	~50m (10GBaseT, Cat6A)	40+ km (SMF)
EMI immunity	Partial (braid reduces, does not eliminate)	Complete — immune to all EMI
DC power over cable	✓ Yes — LNB 13/18V, BUC 24–48V	✗ No — separate power cable required
RF signal (native)	✓ Yes	✗ No — requires RF-to-optical conversion
Bandwidth	DC to 40 GHz (LMR-600)	Practically unlimited (>100 THz)
Field termination	Easy — crimp tool, N-type / SMA / BNC	Requires fusion splicer + cleaver
Cable cost	Lower	Higher
Weight	Heavier	Very light
Minimum bend radius	25mm (LMR-400)	30mm (standard OS2)
Security	Can be passively tapped	Tap causes detectable signal loss
Ground loop / surge risk	Yes — copper conductor	None — glass is non-conductive

When to Use Coaxial Cable

✓ Coaxial is the right choice for:

1. VSAT and satellite IFL runs — Mandatory. Your satellite modem must deliver DC power to the LNB (13V/18V + 22 kHz polarisation tone) and BUC (24–48V) through the same cable that carries the IF signal. Use LMR-400 up to 30m, LMR-600 to 60m, LMR-900 to 80m+ at Ku-band.

2. Two-way radio and base station antenna feedlines — VHF/UHF antenna connections are always coaxial. LMR-400 is the standard for fixed base station installations.

3. RF signal distribution — Splitters, combiners, amplifiers, RF patch panels: anywhere you’re routing or processing a live RF signal, coaxial connections are required throughout the chain.

4. Short runs under 40–50 meters — For L-band and below, coax is simpler, cheaper, and easier to terminate. The attenuation penalty is manageable for short runs.

5. Remote RF power delivery — Any equipment at the far end that needs power over the cable (BUC on a tower, LNB on a dish) requires coaxial IFL — there is no alternative.

6. Field installations — Coax connectors (N-type, SMA, TNC, BNC) are field-terminable with a hex crimp tool. Fusion splicing fiber requires capital equipment and a clean environment.

When to Use Fiber Optic Cable

✓ Fiber optic is the right choice for:

1. Long data backbone runs (>100m) — Any Ethernet or network backbone link over 100m should be fiber. SMF supports 10G Ethernet over 10+ km without amplifiers. Coaxial cable would require impractically thick gauge (LMR-900+) and still fall short.

2. EMI-heavy environments — Generator rooms, industrial motor drives, high-voltage transformer enclosures: fiber is completely immune. Coax braid reduces EMI pickup but does not eliminate it — you’ll see interference on the signal.

3. Building-to-building links — Outdoor aerial or buried runs between buildings: fiber provides natural ground-loop isolation and is immune to lightning surges between structures. Copper cable between buildings can conduct a surge that damages equipment at both ends.

4. High-bandwidth data (40G / 100G / 400G) — These speeds are not achievable over coaxial cable at practical distances. Fiber is the only option.

5. Security-critical installations — Fiber signals cannot be intercepted passively. Any physical tap causes a measurable signal loss that optical monitoring equipment can detect and alert on.

6. Harsh or marine environments — Fiber is immune to moisture ingress effects on signal quality, salt air corrosion of conductors, and temperature-driven changes in impedance.

Why VSAT Always Uses Coaxial — Without Exception

In any VSAT installation — from a single maritime terminal to a large teleport earth station — the IFL between the satellite modem and the outdoor unit (BUC and LNB) must be coaxial cable. The reason is simple: the satellite modem or ODU controller delivers DC power to the LNB and BUC through the same coaxial IFL that carries the IF signal. Fiber optic cable cannot carry DC power.

Fiber-based IF extension systems do exist. They use optical modulators and demodulators with separate power injectors to extend IFL runs beyond 100 meters in large earth station facilities. But these are expensive, complex installations reserved for sites where very long cable runs make standard coax impractical. For any typical VSAT site — from a rooftop dish to a teleport hub — coaxial cable (LMR-400 through LMR-900 depending on run length) is the only practical and cost-effective IFL solution.

Frequently Asked Questions

Can I replace my VSAT coaxial IFL with fiber optic cable?

Not without additional equipment. The BUC and LNB require DC power that can only be delivered over coaxial cable in a standard installation. Fiber-based IF extension systems exist for very long runs (>100m) in large facilities — they use optical modulators with separate power injectors — but they are expensive and complex. For any typical VSAT installation, coaxial cable is the correct and only practical IFL choice.

Which has less signal loss — fiber optic or coaxial?

Fiber wins dramatically. LMR-400 loses approximately 30 dB per 100 meters at Ku-band (12 GHz). Single-mode fiber OS2 loses just 0.2 dB per kilometer at 1550 nm — roughly 15,000 times less attenuation per meter. For data signals over any meaningful distance, fiber is the clear choice.

Is fiber optic cable more expensive than coaxial?

Fiber cable typically costs more per meter, and termination requires a fusion splicer — significant capital equipment. However, for long runs where you’d otherwise need thick-gauge LMR-900 coax plus inline amplifiers, fiber can become cost-competitive overall. For short RF applications under 50 meters, coaxial cable is almost always the lower-cost total solution.

Can fiber optic cable be used as an antenna feedline?

No — not without conversion equipment. Fiber carries digitised optical signals, not analog RF. An antenna feedline must be coaxial to carry the raw RF signal between the antenna and the radio or satellite modem. Any fiber in an RF path requires RF-to-optical conversion at both ends, which adds cost and complexity that makes it impractical for standard installations.

What coaxial cable should I use for Ku-band VSAT IFL runs?

Use LMR-400 for IFL runs up to 30 meters at Ku-band, LMR-600 for 30–60 meters, and LMR-900 for runs beyond 60 meters. All outdoor sections should use weatherproof N-type connectors with proper weatherproofing tape. Never use RG6 or RG58 for VSAT — their attenuation at Ku-band is far too high even for short runs.

Need coaxial cable for your VSAT or satellite installation?
BravoSatcom stocks LMR-400, LMR-600, RG214 — weatherproof N-type connectors included.
We ship across the GCC.

Shop Coaxial Cable →