Running LMR SDR 1.1 from PowerSDR 2.8.0. How to autocalibrate frequency using FT-710 as reference?

| August 30, 2026 | Amateur Radio (Ham Radio) | No Comments

To autocalibrate the LMR SDR 1.1 using your FT-710 as a reference, you will be using the FT-710 to generate a stable carrier signal that PowerSDR can measure and lock onto.

Critical SDR Safety

Never connect the FT-710’s antenna output directly to the LMR SDR. Even at its minimum 5W setting, the FT-710 will instantly destroy the SDR’s Tayloe mixer (74HC4051) and RX circuitry. You must transmit the FT-710 into a dummy load and use a short wire on the LMR SDR to pick up the stray RF leakage.

1.Set Up the FT-710 Reference: Dummy load required.

Connect the FT-710 to a dummy load. Set the frequency to a clean, known value (e.g., 7.150.000 MHz or 10.000.000 MHz). Set the mode to CW or AM and turn the RF power down to the minimum setting (5W) so you can transmit a steady, continuous carrier.

2.Prepare the LMR SDR:

Attach a small piece of wire to the antenna input of the LMR SDR. Place it near the dummy load or FT-710 feedline. This will be enough to pick up the leakage RF signal safely. Power on the LMR SDR.

3.Tune PowerSDR:

Launch PowerSDR 2.8.0 and click the Start button. Tune VFO A to the exact frequency you set on the FT-710. Briefly key the FT-710 to make sure you can see a strong, visible peak on the panadapter.

4.Access the Calibration Menu:Setup.

General”>

In the top menu, click Setup, navigate to the General tab, and then click on the Calibration sub-tab. Look for the Freq Cal section on the left side.

5.Run the Autocalibration:

Click the Use VFO-A button (or manually type the exact frequency into the box). Key the FT-710 to transmit a steady carrier. While the carrier is active and steady, click the Start button in the Freq Cal section.

6.Apply the Offset:

PowerSDR will analyze the received signal, calculate the frequency offset of the Si5351 clock generator on the LMR SDR, and adjust the correction factor until the signal is perfectly centered. Once the process completes, unkey the FT-710, then click Apply and OK.