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STRANGE QRM {UPDATE}




 
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September 19, 2018, 03:45:48 AM *
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KB5MD
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« on: June 25, 2018, 01:48:34 PM »

Anyone else hearing the carrier type interference on 20 meters every 62KHz all up and down the band?,
I hear some of it on 15 meters but not nearly as strong as on 20.  It is a low pitched hum on AM but more of a carrier type with the BFO and appears to vary in strength at 1 second intervals.
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K6IC
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« Reply #1 on: June 25, 2018, 05:10:53 PM »

Have not listened for these noises.

But,   often,  signals that have  a relatively fixed space between them,   are from switching devices  --  power supplies,   battery chargers,   wall warts (still a PS),   etc.   Many times,  one will find that these signals drift across the bands,  but with relatively fixed spacing twix the signal peaks.

Battery chargers and battery tenders often pulsate,   as they wake up to see if a battery needs additional charging.

If these signals are strong,  they could well be from something/s in your residence/shop,  etc.

If possible,  you could  try switching the Main Breaker in the service entrance to OFF,   for any building on your property that has one.   Then use a battery-operated RX or XCVR  to listen to the bands that had those signals.  and so on.

Just guessin'   GL,   Vic
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KB5MD
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« Reply #2 on: July 04, 2018, 05:03:05 PM »

Update on the QRM problem:  It was caused by a network router.  I don't know why it is just now causing a problem as the router has been in operation for a couple of years.  Thank goodness it's used only to control a large format printer in the shop and can be switched off when the printer isn't being used. My internet is on another router.
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W1RKW
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« Reply #3 on: July 04, 2018, 07:40:05 PM »

I'd suspect the routers SMPS as the culprit.  Replace it with a linear wall wart of equal current rating and problem will probably disappear.
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Bob
W1RKW
Home of GORT. A buddy of mine named the 813 rig GORT.
His fear was when I turned it on for the first time life on earth would come to a stand still.
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