1. Introduction
The Surecom SF-103 is a portable frequency counter designed for measuring the frequency parameters of continuous carrier signals from two-way radios. It features a signal strength indicator, CTCSS/DCS decoder, and supports both analog and digital DMR radio signals. Its compact size and intuitive four-button control make it a versatile tool for radio enthusiasts and maintenance personnel.
Image 1.1: Surecom SF-103 Frequency Counter with its main features and specifications listed on the manual cover.
2. Package Contents
Please check the package contents upon unboxing to ensure all items are present:
- 1 x SF-103 Frequency Counter
- 1 x Dual Band UHF/VHF Antenna
- 1 x Belt Clip
- 1 x USB Charger Adapter with Cable
- 1 x English User Manual
Image 2.1: All items included in the SF-103 package.
3. Product Overview
The SF-103 features a clear TFT color display, four control buttons (F1, F2, F3, F4), and an antenna connector. The device is designed for portability and ease of use.
Image 3.1: Various views of the SF-103 Frequency Counter, highlighting its physical design.
Image 3.2: Dimensions of the SF-103 Frequency Counter and its included antenna.
4. Specifications
- Frequency Range: 2MHz-200MHz and 27MHz-2.8GHz (Dual Band)
- Frequency Response Time: 0.1s, 0.2s, 0.25s, 0.5s, 1.0s (CTCSS/CDCSS >0.5-1sec)
- Accuracy: ±2 ~ ±4ppm (TCXO, -45℃ ~ 65℃)
- Display: TFT Color Display, 240 x 320 pixels, LCD Dim level setting
- Decoder: CTCSS/DCS Decoder
- Digital Mode: Supports DMR radio frequency counting
- Battery: Built-in 3.7V Li-ion battery
- Control: 4 buttons
- Auto Power Off: Configurable from 1-9 minutes
- Weight: 113g (Net)
- Water Resistance: Waterproof
- Connectivity Protocol: DMR, Analog
- Tuner Type: UHF/VHF
5. Setup
5.1 Charging the Device
Before initial use, fully charge the SF-103 using the provided USB charger adapter and cable. Connect the cable to the device's charging port and the adapter to a power outlet. The charging battery LED indicator will show the charging status.
5.2 Attaching the Antenna
Carefully screw the dual-band UHF/VHF antenna onto the antenna connector at the top of the SF-103. Ensure it is securely fastened but do not overtighten.
5.3 Initial Power-On
Press and hold the power button (usually F1) to turn on the device. The TFT color display will illuminate, showing the main measurement interface.
6. Operating Instructions
6.1 Power On/Off
- To Power On: Press and hold the F1 button.
- To Power Off: Press and hold the F1 button again. The device also supports an auto power-off feature.
6.2 Frequency Measurement (Analog & DMR)
The SF-103 automatically detects and measures the frequency of continuous carrier signals. Simply bring the device close to the transmitting radio or connect it via an appropriate attenuator (see warnings in Troubleshooting). The display will show the measured frequency and signal strength.
Image 6.1: The SF-103 display showing a measured frequency and CTCSS tone.
Image 6.2: SF-103 in operation, measuring the frequency of a two-way radio.
6.3 CTCSS/DCS Decoding
When measuring an analog signal, the SF-103 can decode and display CTCSS (Continuous Tone-Coded Squelch System) or DCS (Digital Coded Squelch) tones if present. This information is shown on the display below the frequency.
6.4 Display Resolution and Gate Time Selection
The device allows selection of different gate times and display resolutions (digits) for frequency measurement. This can be adjusted via the menu options (refer to the on-screen GUI for specific button functions).
Image 6.3: Frequency Display Resolution and CTCSS/DCS Decode Range Table.
6.5 LCD Dim Level Adjustment
The brightness of the TFT display can be adjusted to suit different lighting conditions. Access this setting through the device's menu.
6.6 Auto Power Off
To conserve battery life, the SF-103 can be configured to automatically power off after a period of inactivity (1-9 minutes). This setting can be adjusted in the device's menu.
7. Maintenance
7.1 Cleaning
Wipe the device with a soft, dry cloth. Do not use harsh chemicals or abrasive cleaners. Ensure no moisture enters the device.
7.2 Battery Care
To prolong battery life, avoid fully discharging the battery frequently. Charge the device regularly, even if not in use for extended periods. Store the device in a cool, dry place.
7.3 Storage
When not in use, store the SF-103 in a protective case or a safe environment to prevent physical damage and exposure to extreme temperatures or humidity.
8. Troubleshooting
- Device not powering on: Ensure the battery is charged. Connect to the charger and try again.
- Inaccurate frequency readings: Ensure the antenna is properly attached. Check for strong interference sources nearby. Ensure the radio being measured is transmitting a stable signal.
- Display issues: Check the LCD dim level setting in the menu. If the issue persists, contact support.
Important Warnings:
- Maximum Direct Input Signal: Do not exceed 5Vp,p for direct signal input.
- Antenna Connection: DO NOT directly connect the SF-103 to the antenna output of a radio transmitter without an appropriate attenuator. Doing so can cause severe damage to the frequency counter.
9. Warranty and Support
9.1 Manufacturer's Warranty
The Surecom SF-103 Frequency Counter comes with a 90-day manufacturer's warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use. It does not cover damage caused by misuse, accidents, unauthorized modifications, or failure to follow the instructions in this manual.
9.2 Technical Support
For technical assistance, warranty claims, or further inquiries, please contact your retailer or the manufacturer's customer support. Refer to the contact information provided with your purchase documentation.