On 25/11/2014 02:10, Phil Allison wrote:

Jeff Layman wrote:

I have a 6-months old Fantasia ceiling fan (mains powered, with
6-speed reversible dc motor) which is causing a lot of interference
on MW. FM is not affected. The interference is there on forward or
reverse rotation, worsens as the speed is increased,, and appears
on portable as well as mains-powered radios.

I can return it to the supplier for replacement or refund, but it
is a bit of a rigmarole to remove and refit. All the electronics
are sealed in, and the only accessible wiring is to the mains
connector. Is there any point in trying some sort of screening or
RFI suppression on the mains wiring before I take it down?


** The instructions say all units must be earthed - is yours?

I hope so! It was installed by a pro electrician and I have a NICEIC
certificate which says so (http://niceic.com/). But I'll check it anyway.

You could try a suppression cap across the line( active to neutral)
at the terminal block - close as possible to the fan itself. A class
X1 or X2 film cap of about 470nF is a good place to start. But I bet
there is one inside the fan already.

The only thing I can get in the next day or so is this delta suppression
filter:
http://www.maplin.co.uk/p/delta-supp...n-filter-rg21x

I expect the fan motor is a BLDC type, possibly operating at mains
voltage, and the pitch of the noise on AM would vary with its speed.

Guess so. The fan often turns in the reverse direction for a second or
so when switched on, then corrects itself.

BTW:

Are you living far from AM transmission sites - say than 50 kms ??

No. The 999kHz local radio transmitter (1kW) is about 15 km away..

BTW 2:

Are you living in a metal clad ( aluminium sided ) building ?

The fan is in a new metal-framed conservatory. The mains-powered MW
receiver in the conservatory is completely swamped by the interference.
But the portable radio is outside, maybe 6 metres from the fan, and that
has the interference superimposed on the station I am listening to. It's
no doubt attenuating the interference, but not enough

Either of the above means the AM signals inside your home will be
very weak.


..... Phil

Thanks for the info and suggestions.

--

Jeff