Lots of HF noise up to UHF

[df7cb]

Hi,

thanks for AntRunner, I like the design a lot!

Unfortunately, I have S9 noise on 2m and S3 on 70cm so I can barely hear the satellites. It seems to be coming from the step motor drivers, when disconnecting the motors, the ESP32 alone is pretty quiet.

Is there any remedy for this? I tried shielding the motor cables, but it only helped on 70cm, 2m is still unusable when the motors are powered.

73,
Christoph DF7CB

[wuxx]

Hello, can you try replacing the stepper motor driver for testing? Currently, we are using A4988, and there should be many alternative models on the market. So far, no other customers have reported interference issues

[df7cb]

Thanks for the idea, will give that a try and report here.

[df7cb]

Status update: I got two TMC2209 boards, but it only improved the HF noise a tiny bit. I'll try packing the ESP32 board into a shielded box next.

[sm7duz-lab]

Is the noise problem a general problem?
I would like to order, but not as long as the problem is not resolved.
Thanks/SM7DUZ

[Ricapar]

@df7cb - you're not the only one. I got this setup off Tindie not too long ago. I have an Arrow Antenna mounted on it for just VHF right now, and when it's powered on the noise level is through the roof.

The screenshot above I think demonstrates the effect. I had unplugged the rotor from power, and then plugged it back in. You can see right away when the noise comes back.

I even physically disconnecting the antenna from it, thinking it may be some noise induced via the physical contact - but no, it's just generating a ton of RF noise right around 2m which makes this near impossible to use for weak signals. It's just going to blow them away.

If you find anything, I would love to figure out a solution since otherwise it's an nice setup.

[wuxx]

Hello, can you try wrapping the motor with electromagnetic shielding material to see if there is any improvement

[Ricapar]

I have some faraday cloth and tape on-order, I'll report back on if it helps or not!

[sm7duz-lab]

Hello, thanks for the information. I hope you get positive results. My suggestion is to use clamp-on ferrite cores as much as possible to the motor wires. Use #43 or #61 material for the cores. Following this with interest. Den lör 2 aug. 2025 04:35Rich Acosta ***@***.***> skrev:

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*Ricapar* left a comment (wuxx/AntRunner#13) <#13 (comment)> I have some faraday cloth and tape on-order, I'll report back on if it helps or not! — Reply to this email directly, view it on GitHub <#13 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BVOBIKTRDP75TKT7NGENA5L3LQPVJAVCNFSM6AAAAACABTDM7SVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTCNBWGE2DONRZGM> . You are receiving this because you commented.Message ID: ***@***.***>

[Ricapar]

Following up on this one… I tried a few things:

• Wrapped the wires in faraday tape.
• Put as many ferrite chokes as I could fit on the wire while still being able to move.
• Draped a faraday blanket over the whole thing.

I still get overwhelming amounts of noise whenever the servos are plugged in. The noise is definitely coming from the servos.

Any ideas? Suggestions?

[wuxx]

Hello, could you try wrapping the motor with electromagnetic shielding tape

[sm7duz-lab]

Try a 100 uF capacitor between VMOT and GND. Short leads. Den tis 26 aug. 2025 02:37wuxx ***@***.***> skrev:

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*wuxx* left a comment (wuxx/AntRunner#13) <#13 (comment)> Hello, could you try wrapping the motor with electromagnetic shielding tape — Reply to this email directly, view it on GitHub <#13 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BVOBIKW4QNDPUQEEPDBP4YT3POT55AVCNFSM6AAAAACABTDM7SVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTEMRSGE2TGOBUGQ> . You are receiving this because you commented.Message ID: ***@***.***>

[nmaster2042]

I'm interested by this rotator but I'm worried by this issue.

Have you managed to solve the issue ?

What kind of PSU are you using ?