Product Overview

SF-401PLUS Frequency Counter

Introduction

Measures frequency parameters of continuous carrier signals from walkie-talkies with signal strength indication.
Designed for test and maintenance personnel and wireless enthusiasts.
Portable; covers most two-way radio frequency ranges.
Features 4-button control and compact size.
Operates with TCXO for stable frequency compensation (±2 to ±4 ppm accuracy from -45° to 65°).
Supports 2m HAM radio, VHF, UHF, DMR radio signals.
Includes digital mode for DMR radios only.

Features & Specifications

Frequency range: 27 MHz - 3000 MHz (*27-100 MHz not guaranteed)
CTCSS/DCS decoder for 136-174 MHz and 400-520 MHz bands only
Frequency digital resolution: 0.000 or 0.0000 (±0.001)
Frequency response time: 0.2-0.5 s (CTCSS/DCS 0.5-1 s)
TFT Color Display 240x320 pixels with adjustable brightness
Built-in rechargeable Li-ion battery, approx. 113 g weight
Auto power off (1-9 minutes) with LED battery charging indicator

Usage Highlights

Power On/Off: Hold [black key] for 2 sec to power on; hold for 4 sec to shutdown.
Charging: Connect micro USB; red LED = charging, green LED = full.
Signal Testing: Keep transmitter near antenna with green signal bar for valid measurement; red means too close, low bar means weak signal.
Digital DMR Mode: Press [F3 Digital] on measuring screen (shows frequency with 3 decimals).
Menu Settings: Enter with [F1], navigate with [F3]/[F4], edit with [F2]. Save and exit with [F4].
RF Defect Level: Lower levels increase sensitivity.
CTCSS/DCS Decoding: Works only in ANALOG mode with radio frequency 136-174 MHz or 400-520 MHz.

CTCSS Frequencies Table (Hz)

CTCSS Frequencies (Hz)
50.0	97.4	151.4	192.8
55.0	100.0	156.7	196.6
67.0	103.5	159.8	199.5
69.3	107.2	162.2	203.5
71.9	110.9	165.5	206.5
74.4	114.8	167.9	210.7
77.0	118.8	171.3	218.1
79.7	123.0	173.8	225.7
82.5	127.3	177.3	229.1
85.4	131.8	179.9	233.6