RF interference from soft start “Valet” vacuum cleaner

Thread Starter

Short Sir Kit

Joined May 5, 2020
1
Hi everyone. I listen to an AM radio in a spare bedroom and experience a lot of interference. There is a Valet ducted vacuum cleaner unit mounted on the outside wall. The control wires that carry low voltage to the wall inlet socket run several meters up the wall cavity and across the ceiling of that bedroom. Whilst trying to track down the source of interference the only way to make it disappear is to unplug the outdoor vacuum unit. Intrigued, I opened up the vacuum and to my surprise it has a relatively complex circuit board, not a simple relay to power the AC motor that I expected. The only “special” function is a soft-start of the motor when energised. Any ideas how to get rid of the interference? Assuming the low voltage wires were acting as an antenna I tried adding small capacitors between them and ground to shunt any RF. This had a minor improvement.
 

MisterBill2

Joined Jan 23, 2018
18,519
If the vacuum assembly has a metal enclosure that should be grounded. If the remote is inly ON/OFF, you can try changing the remote connection to only a short connection at the vacuum (Disconnect the remote for this check))to see if it is the long control leads delivering the noise. If that is the case, then replace the remote connection wires with shielded twisted pair. with the shield grounded to the vacuum housing.
 
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