ARRL

Secure Site Login

Forum Home - Rules - Help - Login - Forgot Password
Members can access, post and reply to the forums below. Before you do, please first read the RULES.

Chamberlain garage opener causes RFI

Jan 25th, 14:46

K0NXM

Joined: Aug 19th 2002, 00:00
Total Topics: 0
Total Posts: 0
I have a Chamberlain garage opener that was installed several years ago, to replace an older one. It causes RFI that is evident on AM BC and up to 80m. It has been suggested before that the LED bulbs in it may make interference, but the noise persists even with no bulbs. I have found the noise disappears when both the opener switch and the IR safety sensors (at bottom of door) are disconnected - the noise originates inside the unit, and is radiated along the control lines. So far, I've tried clip-on ferrites, LC low-pass filters, and toroidal inductors in series with the lines, to no avail. Maybe I need more inductance? Has someone else solved this issue successfully? Thanks,
Jan 25th, 16:24

W1VT

Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Just a turn or two is normally insufficient on 80M. You typically want 10 to 15 turns through a toroid. If the wires are thin it is more effective and cheaper to run several wires through a large toroid. I use FT-240-43 or FT-240-31 toroids--the latter is more expensive but a little more effective at low frequencies.

Zak W1VT
ARRL Senior Lab Engineer
Jan 25th, 19:09

K0NXM

Joined: Aug 19th 2002, 00:00
Total Topics: 0
Total Posts: 0
Developing... I used a couple commercially wound toroids (about 20 bifilar turns each), in series with the lines from the sensors and the remote switch - no help. I have now also detected the same interference on some power circuits in the house, maybe it's coupling to the front garage lights that are in close proximity to the sensors. I think I'll try using shielded twin-conductor cable next, as I think I have it on hand. I never realized there was this problem until trying to get on 160...

Back to Top