1. Introduction
The LDG AT-200PROII is a versatile automatic antenna tuner designed for amateur radio applications. It provides efficient antenna matching across a wide frequency range, from 1.8 MHz to 54 MHz, and supports power levels up to 250 watts for SSB and CW modes. This tuner features a two-position antenna switch, allowing users to quickly switch between two different antennas. Its advanced memory tuning system stores up to 2,000 tuning solutions for rapid recall, ensuring near-instantaneous tuning on frequently used frequencies.
This manual provides comprehensive instructions for the setup, operation, and maintenance of your AT-200PROII tuner, ensuring optimal performance and longevity.
Product Views
Figure 1: Front panel of the AT-200PROII tuner, showing controls and LED displays for power and SWR.
Figure 2: Rear panel of the AT-200PROII tuner, displaying antenna, ground, and power connections.
Key Features
- Power Handling: 5 to 250 watts SSB and CW; 100 watts on 6M; 75 watts with PSK or digital modes.
- Display: Easy-to-read LED bargraph display for RF power, SWR, and status indicators.
- Memory: 4,000 memories (2000 for each antenna) for instantaneous band changing.
- Antenna Switch: Two-position antenna switch with memories for four antennas on each position.
- Tuning Speed: 0.5 to 6 seconds for a full tune, less than 0.1 second for memory tune.
- Frequency Counter: Built-in frequency counter for memory operation.
- Frequency Coverage: 1.8 to 54.0 MHz.
- Impedance Matching: Tunes 6 to 800 ohm loads (16 to 150 ohms on 6M), 6 to 3600 ohms with optional 4:1 Balun (LDG RBA 4-1).
- Antenna Compatibility: Suitable for Dipoles, Verticals, Vees, Beams, or any Coax Fed Antenna.
- Power Supply: Includes 6' DC power cable.
- Dimensions: 9.5D x 7.1W x 2.0H inches.
- Weight: 2 pounds.
2. Setup
2.1 Unpacking and Inspection
Carefully remove the AT-200PROII from its packaging. Inspect the unit for any signs of physical damage that may have occurred during shipping. If any damage is found, contact your dealer immediately.
2.2 Power Connection
The AT-200PROII requires a 12 VDC power source, capable of supplying 750 mA. Use the included DC power cable to connect the tuner to a suitable power supply. Ensure correct polarity: the center pin of the power jack is positive (+).
- Connect the small barrel connector of the DC power cable to the "12 VDC" jack on the rear panel of the tuner.
- Connect the other end of the cable to your 12 VDC power supply.
2.3 Antenna Connections
The AT-200PROII features two antenna outputs (Ant 1 and Ant 2) and a ground terminal. These are SO-239 (UHF female) connectors.
- Connect your primary antenna to the "Ant 1" connector.
- If using a second antenna, connect it to the "Ant 2" connector.
- Connect a good RF ground to the "Gnd" terminal. This is crucial for optimal performance and safety.
2.4 Transceiver Connection
Connect the output of your transceiver to the "Tx" connector on the rear panel of the AT-200PROII using a standard 50-ohm coaxial cable (e.g., RG-8X, RG-213).
- Ensure all connections are secure and properly tightened.
- Do not apply power to the tuner or transmit until all connections are complete.
3. Operating Instructions
3.1 Basic Operation
Once connected, turn on the AT-200PROII by pressing the "Power" button on the front panel. The power LED will illuminate.
3.2 Automatic Tuning Cycle
The AT-200PROII is designed for automatic operation. It will initiate a tuning cycle whenever the SWR exceeds a preset limit (typically 2.0:1). To manually initiate a tune:
- Select the desired antenna using the "Ant" button (Ant 1 or Ant 2).
- Transmit a continuous carrier (e.g., in FM, AM, or CW mode) at a low power level (5-10 watts is sufficient for tuning).
- Press the "Tune" button on the front panel. The tuner will begin searching for the lowest SWR.
- Once tuning is complete (typically 0.5 to 6 seconds), the SWR LED bargraph will indicate the matched SWR. You can then increase your transmit power.
Note: If the tuner has previously stored settings for the current frequency, it will recall them almost instantly (less than 0.1 second), significantly speeding up the tuning process.
3.3 Manual Tuning (Advanced)
For specific tuning adjustments or in challenging matching situations, the AT-200PROII allows for manual adjustment of inductance (L) and capacitance (C).
- Press the "Func" button to enter manual tuning mode.
- Use "C Up" and "C Dn" buttons to adjust capacitance.
- Use "L Up" and "L Dn" buttons to adjust inductance.
- Observe the SWR bargraph while making adjustments to achieve the lowest SWR.
- Press "Store" to save the manual settings for the current frequency.
3.4 Memory Functions
The AT-200PROII features 2,000 memory locations per antenna (4,000 total). It automatically stores tuning solutions for frequencies you use. When you return to a previously tuned frequency, the tuner will recall the settings for near-instantaneous matching.
- Automatic Recall: Simply transmit on a frequency, and if a memory exists, the tuner will apply it.
- Manual Store: After a successful tune (automatic or manual), press the "Store" button to explicitly save the current settings.
3.5 Antenna Switching
The "Ant" button cycles between Antenna 1 and Antenna 2. The active antenna is indicated by an LED. Each antenna position has its own set of 2,000 memories.
3.6 Power and SWR Display
The front panel features two LED bargraphs:
- PWR (Power): Displays forward and reverse power. The "Scale" button toggles between 25W and 250W full-scale readings.
- SWR: Displays the Standing Wave Ratio. Aim for the lowest possible SWR (ideally 1.0:1).
The "Peak" button toggles the power meter between peak and average power readings.
4. Maintenance
4.1 Cleaning
To clean the exterior of the AT-200PROII, use a soft, dry cloth. For stubborn marks, a slightly damp cloth with mild soap can be used, followed by drying. Avoid abrasive cleaners or solvents, as these can damage the finish and labels.
4.2 Storage
When not in use for extended periods, store the tuner in a cool, dry place, away from direct sunlight and extreme temperatures. Disconnect all cables before storage.
5. Troubleshooting
5.1 Common Issues and Solutions
| Problem | Possible Cause | Solution |
|---|---|---|
| Tuner does not power on. | No power, incorrect polarity, faulty power supply. | Check 12VDC power connection and polarity. Test power supply. |
| Tuner does not tune or achieve low SWR. | Antenna issue, insufficient power for tuning, frequency out of range, extreme impedance mismatch. | Check antenna connections. Ensure at least 5W transmit power. Verify frequency is within 1.8-54 MHz. Consider adding an optional balun for very high/low impedances. |
| SWR reading is high after tuning. | Antenna system cannot be matched, faulty coaxial cable. | Inspect antenna and feedline for damage. Try a different antenna. Ensure proper grounding. |
| Tuner makes clicking noises but doesn't tune. | Normal operation during tuning cycle (relays). | This is normal. The relays are switching components to find a match. |
If you encounter issues not listed here or if the suggested solutions do not resolve the problem, please contact LDG Electronics customer support.
6. Specifications
6.1 Technical Data
| Feature | Detail |
|---|---|
| Product Dimensions | 9.5 x 7.1 x 2 inches |
| Item Weight | 2 pounds |
| Model Number | AT-200PROII |
| Manufacturer | LDG Electronics |
| Compatible Devices | Radio |
| Connector Type | RCA (for control, not RF) |
| Connectivity Technology | Radio Frequency |
| Antenna Type | Radio |
| Frequency Coverage | 1.8 to 54.0 MHz |
| Power Range | 5-250 Watts SSB/CW, 100 Watts 6M, 75 Watts Digital Modes |
| Tuning Impedance Range | 6 to 800 ohms (16 to 150 ohms on 6M) |
| Memory Locations | 4,000 (2,000 per antenna) |
| Power Requirement | 12 VDC @ 750 mA |
7. Warranty and Support
7.1 Warranty Information
The LDG AT-200PROII comes with a 2-Year 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, accident, unauthorized modification, or improper installation. Please retain your proof of purchase for warranty claims.
7.2 Customer Support
For technical assistance, troubleshooting, or warranty service, please contact LDG Electronics directly. Visit their official website for the most current contact information, FAQs, and additional resources.
Manufacturer: LDG Electronics
Address: 1445 Parran Road, St. Leonard MD 20685
Phone: 410-586-2177
Website: www.ldgelectronics.com
