Bullseye LNB Calibrator – Arduino‑Based LO Alignment Tool (Designed by G4EML)

This Bullseye LNB Calibrator is a purpose‑built, Arduino‑driven alignment tool designed by G4EML to precisely adjust the Local Oscillator (LO) frequency of the Othernet Bullseye Ku‑Band LNB. The Bullseye LNB is widely regarded as one of the most stable consumer‑grade LNBs available, thanks to its internal Temperature‑Compensated Crystal Oscillator (TCXO). However, like all oscillators, it can drift over time due to temperature changes, aging, and mechanical handling. This calibrator gives you the ability to re‑align the LO frequency yourself, restoring optimal accuracy for applications such as QO‑100 operation, beacon monitoring, and high‑precision satellite reception.

✔ Purpose‑Built for the Othernet Bullseye LNB

The Bullseye LNB is factory‑calibrated to within ±10 kHz of its nominal 9750.0 MHz LO. This calibration is performed using a proprietary interface on the red F‑connector. Thanks to documentation released by Othernet and Sy Science & Technology, G4EML has engineered a fully compatible calibration interface that allows end‑users to safely and accurately adjust the LO frequency.

✔ Arduino‑Powered Calibration

At the heart of the calibrator is a standard Arduino Nano, chosen for its low cost, availability, and ease of programming. The included firmware (Bullseye_Calibrator.ino) communicates with the LNB using a 9600‑baud serial protocol with +15V signaling levels. A simple level‑shifting circuit is included in the design, allowing the Arduino to interface directly with the LNB’s adjustment port.

✔ Stand‑Alone or PC‑Controlled Operation

You can operate the calibrator in two ways:

1. Stand‑Alone Mode

• Power the calibrator with 18–30V DC (two 9V batteries or an external supply).

• Connect the calibrator to the LNB’s red F‑connector.

• Use the Left and Right buttons to adjust the LO in ~200 Hz steps.

• Hold a button for rapid tuning (10 steps per second).

• Press SAVE to store the new calibration permanently inside the LNB.

• Press all three buttons to restore factory defaults.

2. PC Mode

• Connect via USB to any computer.

• Use a terminal program at 9600 8N1.

• Send single‑character commands to adjust the LO.

• Ideal for automated or scripted calibration workflows.

✔ Includes 3D‑Printable POTY Feed Adaptors

The repository also includes STL files for 3D‑printing replacement LNB caps with:

• 22 mm copper tube adaptor

• 23 mm copper tube adaptor

These allow the Bullseye LNB to be directly coupled to a dual‑band POTY feed, making it ideal for QO‑100 uplink/downlink setups.

✔ Complete Hardware Documentation

Everything needed to build the calibrator is included:

• Full schematic (PDF)

• Bill of Materials with Farnell part numbers

• Gerber files for PCB fabrication

• Both SMT and through‑hole PCB versions

• Clear LO Re‑Alignment Procedure PDF

No components are critical—common, inexpensive parts can be used.

⚠ Important Notice

Adjusting your Bullseye LNB voids the manufacturer’s warranty. Use this tool at your own risk. This is clearly stated in the official alignment documentation.

Why You Need This Tool

If you rely on:

• QO‑100 narrowband or wideband operation

• GPS‑locked frequency references

• High‑precision beacon monitoring

• SDR systems that require accurate LO stability

…then this calibrator ensures your Bullseye LNB performs at its absolute best.

Author Credit

This design, firmware, and documentation were created by G4EML, who generously published the entire project open‑source for the amateur radio community.