C-pap rfi

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W8BHA
Posts: 1
Joined: Tue Dec 08, 2015 11:07 pm

C-pap rfi

Post by W8BHA » Tue Dec 08, 2015 11:21 pm

I am a CPAP user who's tired of dealing with rfi that extends from the am broadcast band up to 30mhz on a receiver near the machine.
any suggestions on steps I might take to elliminate the rfi which seems to be coming from the machines compressor?

Thanks, Jim

wa3tfs
Posts: 4
Joined: Thu Mar 31, 2016 2:38 am

Re: C-pap rfi

Post by wa3tfs » Sat Apr 02, 2016 6:37 pm

First, you must determine if the noise is being radiated or conducted on the power wiring. If your Cpap has a back up battery, (some do) unplug from the mains and see if the interference has changed. If so, that shows it is coming along the power wiring. If not, disconnect the antenna cable from the radio and see if the noise does away. If it does, the noise is being radiated. You can have a combination as well.
If the noise is being conducted on the power line, a clamp on ferrite (or several) on the wire may help. If it is being radiated, only shielding or distance will help. The device must comply with FCC regulations and if it is excessively noisy, it may be defective. It then may be best to contact your medical equipment supplier to fix the problem.
I have designed these machines and a properly designed and manufactured one does not have this problem. Usually the only interference is narrow spikes related to the microprocessor clock frequency. Compressor noise usually indicates a faulty motor or power supply.
I hope this helps.
Jim

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