SF401 Plus 27MHz-3000MHz Radio Portable Frequency Counter Meter

Our review of the SF401 Plus finds it to be a compact, practical frequency counter aimed at radio hobbyists, field technicians and anyone who needs a quick read on continuous carrier signals. The single biggest reason to buy is its broad 27MHz-3000MHz coverage combined with built-in CTCSS/DCS decoding, which lets the user identify tone information and measure signal frequency and strength in one small package. It is most useful when testing two-way radios and sniffing unknown tones on the go, and the rechargeable battery makes it easy to use away from a bench.

Key Features

• Wide frequency range: The 27MHz to 3000MHz span covers most handheld and mobile two-way radios you will encounter, reducing the need for multiple instruments.
• CTCSS/DCS decoder: Built-in tone decoding helps identify continuous tone squelch and digital codes so you can verify channel access tones quickly.
• Signal strength indicator: The meter shows signal level so users can assess receive conditions and antenna coupling while measuring frequency.
• Compact, battery powered: A built-in Li-ion battery and small 113g form factor let technicians carry the counter in a pocket for field troubleshooting.
• TCXO stability: Temperature compensated crystal oscillator provides stable frequency accuracy across a wide temperature range, improving measurement reliability.
• Simple controls: Four-button operation and auto power off make routine checks fast and keep power use low between measurements.

Who It's For

The SF401 Plus is best for radio enthusiasts, amateur radio operators and field service techs who need a handheld tool to verify carrier frequency, check signal strength and decode CTCSS/DCS tones. Its small size and rechargeable battery suit mobile use and quick site checks rather than continuous lab testing.

Those who need lab-grade traceable calibration or integrated spectrum analysis functions should look elsewhere; the SF401 Plus is optimized for practical, in-field measurements and tone identification rather than exhaustive bench diagnostics.

Pros & Cons

Pros

• Broad frequency coverage with reliable CTCSS/DCS decoding for tone identification.
• Compact, lightweight design with a built-in Li-ion battery for portable use.
• Good stability from the TCXO, helping maintain accuracy across temperatures.

Cons

• Interface and four-button control receive mixed feedback on ease of use from some customers.
• Tone readouts and accuracy can feel inconsistent to users comparing to higher-end lab instruments.

Specifications

Frequency range	27MHz - 3000MHz
CTCSS/DCS	Built-in decoder
Display	Color LCD with dim level setting
Oscillator	TCXO, 2 - 2.5ppm
Response time	0.2s
Power	Built-in Li-ion battery, USB charging
Net weight	113g

Our Verdict

The SF401 Plus is a pragmatic pocket frequency counter for anyone working with two-way radios who needs wide coverage plus tone decoding in a portable package. It offers strong value for in-field troubleshooting thanks to broad frequency coverage, TCXO stability and a rechargeable battery, though those needing lab-level precision or a more intuitive menu layout should consider higher-end instruments.

Frequently Asked Questions

Does this unit decode CTCSS and DCS tones?
Yes. The SF401 Plus includes a built-in CTCSS and DCS decoder to identify tone and digital squelch codes on continuous carrier signals.

How accurate is the frequency measurement?
The meter uses a TCXO with about 2 to 2.5ppm stability across temperature, providing reliable field accuracy for most two-way radio checks.

What is included in the package?
The unit ships with the SF401 Plus frequency counter, a UHF antenna, user manual, USB charging cable and USB AC adapter.