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eHam Forums => RFI / EMI => Topic started by: KD2HCU on January 25, 2023, 06:50:06 AM

Title: 17 Meter interference
Post by: KD2HCU on January 25, 2023, 06:50:06 AM
   I've been experiencing rfi/emi on the entire 17 Meter band on my Yaesu 991a.  The spectrum scope looks like the teeth on a saw.  I disconnected the power supply and ran on battery, shut off various things in the house, even tried a different radio on batteries with a hamstick antenna to see if it was in the radio, no good.  I need a few ideas as to what would cause so much trouble over the entire 17 M band but no problems on any other frequeny.
Title: Re: 17 Meter interference
Post by: W9IQ on January 25, 2023, 07:30:28 AM
You live in an area with enough population density that you need to first determine if the source is on your property or elsewhere. To do this you need to run the radio off a battery (not a UPS). Turn off the main breaker in your home. Account for any battery operated devices such as alarm systems, routers, UPS, sump pumps, etc. that may still be powered.

If the noise goes away, the source is within your direct control. Turn on the main and turn off branch circuits one by one until the noise goes away. Then research everything on that branch.

If the noise did not go away with the mains switched off, it could be one of your battery operated devices is the source or it is a noise source outside of your direct control. In this case, use your G90 with a few inch loop antenna as a portable detector in your house and neighborhood.

- Glenn W9IQ
Title: Re: 17 Meter interference
Post by: KL7CW on January 25, 2023, 11:30:00 AM
In the past many folks posted that solar powered lights were sources of RFI. I do not have any, but consider this possibility also.
             KL7CW
Title: Re: 17 Meter interference
Post by: KH6AQ on January 25, 2023, 05:43:36 PM
The next step might be to shut off all AC to your house. If the noise is still there is it probably coming from outside your home.
Title: Re: 17 Meter interference
Post by: KD2HCU on January 26, 2023, 08:26:10 AM
Thank you all for responding.
Title: Re: 17 Meter interference
Post by: WA3SKN on January 31, 2023, 03:43:34 PM
You have a local noise source.  And you need to locate it and filter it.
You will need a directional antenna.  A Loop with a circumference of 4 ft of wire should do.  Rotate the loop to get a null bearing, then move locations and get another.  Where the bearings meet should be the location of the noise... hopefully nearby in your house where you can fix it.
Good luck!

-Mike.