Testing Coaxial Cable: The Complete Guide

Published by Wassalat Technical Team

You've installed your coaxial cable, terminated the connectors, and secured everything in place. But how do you know it's working properly?

This comprehensive guide covers everything you need to know about testing coaxial cable—from simple continuity checks to advanced signal quality measurements. Whether you're a professional installer or a DIY enthusiast, proper testing ensures reliable performance.

Why Test Coaxial Cable?

Testing your coaxial cable installation is essential for several reasons:

1. Verify Installation Quality

Ensure the cable is intact, connectors are properly terminated, and the signal path is clear.

2. Identify Problems Early

Catch issues before they cause service interruptions or signal degradation.

3. Document Baseline Performance

Establish a baseline for future troubleshooting and system validation.

4. Comply with Standards

Professional installations often require certification to industry standards.

5. Ensure Customer Satisfaction

Deliver reliable, high-quality performance that meets expectations.

Testing Tools Overview

Tool Comparison

Recommended Tools by Application

Continuity Testing

Continuity testing verifies that the cable is electrically intact and has no shorts or opens.

How to Test Continuity with a Multimeter

1. Set multimeter to resistance (Ohms) or continuity mode
2. Test the center conductor – Connect one probe to each end of the center conductor. Expect < 1 ohm for short cables.
3. Test the shield – Connect one probe to each end of the shield. Expect < 1 ohm.
4. Test for shorts – Connect one probe to the center conductor and the other to the shield at the same end. Expect no continuity (open circuit).

Continuity Test Results

Signal Level Testing

Signal level testing measures the strength of the signal at the receiving end of the cable.

How to Test Signal Level

1. Connect a signal meter to the cable end
2. Set to the correct frequency or channel
3. Read the signal level in dBmV (for TV) or dBm (for RF)
4. Compare to acceptable levels

Signal Level Standards

Using a TV/Receiver Signal Menu

Most modern TVs and satellite receivers have a built-in signal meter:

• ? TV Menu → Settings → Signal Information
• ? Satellite Receiver → Settings → Signal Strength/Quality
• ? Cable Modem → 192.168.100.1 → Signal Levels

Signal Loss Testing

Signal loss testing measures how much the signal attenuates as it travels through the cable.

How to Test Signal Loss

1. Measure signal level at the source (transmitter end)
2. Measure signal level at the destination (receiver end)
3. Calculate the difference = Source Level - Destination Level
4. Compare to expected loss for the cable type and length

Acceptable Loss Limits

VSWR Testing

VSWR (Voltage Standing Wave Ratio) measures how much signal is reflected back from the cable or antenna. A perfect match is 1:1.

Understanding VSWR

How to Test VSWR

1. Connect a VNA or SWR meter to the cable or antenna
2. Set the frequency to your operating frequency
3. Read the VSWR value
4. Compare to acceptable levels

Common Causes of High VSWR

• ❌ Impedance mismatch – 50Ω cable connected to 75Ω equipment
• ❌ Damaged cable – Kinks, cuts, or bends
• ❌ Poor termination – Loose or damaged connectors
• ❌ Wrong connector type – Mixing 50Ω and 75Ω connectors
• ❌ Damaged antenna – Broken or corroded

Interference Testing

Interference testing identifies external signals that may be affecting your cable's performance.

How to Test for Interference

1. Use a spectrum analyzer connected to the cable
2. Scan the frequency range of your application
3. Look for unexpected signals (spikes or noise)
4. Identify the source of interference if found

Common Interference Sources

Interpreting Results

Pass/Fail Criteria

When to Replace a Cable

• ? Continuity failure – Broken center or shield
• ? Short circuit – Center touching shield
• ? High VSWR – > 2.0:1
• ? Excessive signal loss – More than 50% above expected
• ? Water ingress – Visible moisture or corrosion
• ? Physical damage – Kinks, cuts, or crushed sections

Frequently Asked Questions (FAQ)

1. How do I test coaxial cable without a tester?

Use a multimeter to check continuity. You can also connect the cable to a known working device (TV, modem) and check for signal.

2. What is a good VSWR for coaxial cable?

A VSWR of 1.5:1 or lower is considered good. VSWR below 1.2:1 is excellent.

3. How do I measure signal loss in coaxial cable?

Measure signal level at both ends and calculate the difference. Use a signal meter or spectrum analyzer.

4. What is the maximum acceptable signal loss?

For TV, maximum loss is 8-10 dB. For satellite, 6-8 dB. For broadband internet, 10 dB.

5. Can a multimeter test coax cable?

Yes, a multimeter can test continuity and shorts. It cannot test signal quality, VSWR, or impedance.

6. How do I test for interference?

Use a spectrum analyzer connected to the cable. Look for unexpected signals in your frequency band.

7. What is TDR testing?

TDR (Time Domain Reflectometry) sends a pulse down the cable and measures reflections to locate faults and measure cable length.

8. How often should I test coaxial cable?

Test after installation and during troubleshooting. Also test if you suspect damage, water ingress, or performance degradation.

9. What causes signal loss in coaxial cable?

Signal loss is caused by conductor resistance, dielectric absorption, skin effect, leakage, and connector loss.

10. Can I test coax with a tone generator?

Tone generators are used for cable identification, not signal quality testing. Use a proper cable tester for signal quality.

? Related Articles

• Complete Guide to Coaxial Cables
• Cable Attenuation Explained
• Installing Coaxial Cable
• Coaxial Cable Connectors

Last Updated: July 2026

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