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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 30th Mar 2024, 10:56 am   #1
vinrads
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Default Radio interference on steroids!

I was happily working away testing some AF117's on a bush VTR 103 when on switch on I was greeted with the most
horrendous noise totally wiping out all M/W and L/W could it be the transistor on test going into oscillation, no it was outside interference ,my first thoughts were next doors massive flat screen T/V but no it turned out to be an LED lamp in the living room my wife had just switched it on .Mick.
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Old 30th Mar 2024, 11:04 am   #2
Station X
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Default Re: Radio interference on steroids!

LED lamps and tubes are notorious for creating interference.
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Old 30th Mar 2024, 11:21 am   #3
paulsherwin
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Default Re: Radio interference on steroids!

The big problem with them isn't that they inherently produce RFI, but that they can develop faults which produce massive amounts of RFI while they still appear to work normally. All SMPSUs can do this, but LED GLS lamps seem particularly prone to it. CFLs can do it too.
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Old 30th Mar 2024, 6:51 pm   #4
Graham G3ZVT
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Default Re: Radio interference on steroids!

Quote:
Originally Posted by vinrads View Post
I was happily working away testing some AF117's ...
I got that far reading your post, and I thought it was going in a different direction.

I remember testing some transistors 50 years ago, they were out of the front end of a Pye Cambridge AM10B transceiver, and each time I connected the probes of my moving-coil mustimeter there was an almighty hiss from another receiver at the other side of the shack.
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Old 30th Mar 2024, 9:21 pm   #5
m0cemdave
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Default Re: Radio interference on steroids!

Some LED lamps are much worse than others. All the lights in my house are now LED, except for the room I use as a radio shack which still uses incandescents. I turn all the others off if I want to use the radios, and the noise level drops several S-points.

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... and each time I connected the probes of my moving-coil mustimeter there was an almighty hiss from another receiver at the other side of the shack.
Maybe the meter was applying enough voltage to the b-e junctions for them to behave as noise diodes? Zeners are notorious for it.
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Old 31st Mar 2024, 2:14 pm   #6
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Default Re: Radio interference on steroids!

Some LED household lamps are driven by SMPS circuitry and can be horrendously noisy, more often now they tend to use multiple series connected LEDs whose forward voltages totals to just under line voltage, the current regulation being done linearly.
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