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Old 21st Aug 2019, 1:28 am   #20
space_charged
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Join Date: Dec 2014
Location: West Midlands, UK.
Posts: 315
Default Re: Spitfire Am Transmitter Hum (Buzz)

Quote:
Originally Posted by G6Tanuki View Post
I'm thinking that this could be a form of "Modulation Hum".
Yes I have experienced that. Looking for sources of hum and using batteries to supply the modulator didn't remove the hum. Researching on the web, I came across modulation hum and it seemed a very good explanation. All the wiring in a house is carrying a high amplitude 50Hz ac waveform. It also acts as an aerial, receiving and re-radiating other transmissions. These get modulated with the mains frequency.

Of course, you shouldn't really be radiating anything with your modulator. Keep it all screened and you won't have a problem.
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