For control the autotuner, the E3 encoder in you mcHF SDR radio must be with a button.

Chinese cases are usually equipped with such encoders.

If you have an E3 encoder without a button, first replace it with an encoder of the same height with a button

(encoder not included in DIY KIT)

You need to buy either:

PEC11R-4215K-S0024 Shaft Type: Knurled or PEC11R-4215F-S0024 Shaft Type: D / Flatted

It depends which shaft type is on the other encoders in your radio

Both of them are 21.5 mm high (from PCB to end of shaft) and all with a switch

You can download installation and operation manual by click here (v1.05 Feb 12, 2020)

1. Tuning mode

Press and hold the E3 encoder button.

The LD2 LED will turn on green for 2 seconds.

After that, the LED will blink green for 2 seconds.

At this moment, while the green LED is blinking, release E3 encoder button

and press the TUNE button of the transceiver.

The LED will turn orange and the autotuner will begin tuning.

When tuning is completed, the LED will turn red.

Press the TUNE button of the transceiver. The LED will turn off and the transceiver will go to RX.

2. BY PASS mode

Press and hold the E3 encoder button.

The LD2 LED will turn on green for 2 seconds.

Release the E3 encoder button while the LD2 LED is lit continuously.

The LED will blink three times and the autotuner will switch to BY PASS mode.

3. Disabling BY PASS mode

Press and hold the E3 encoder button.

The LD2 LED will turn on green for 2 seconds.

Release the E3 encoder button while the LD2 LED is lit continuously.

The LED will flash once and BY PASS mode will be turned off.