(Warning: Loud) What is this sound in the MW band?

3 years ago by ChaoticNeutralCzech to c/hamradio

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Heard this sound at about 1200 kHz AM using an analog consumer radio in eastern Czech Republic. (Could be a superheterodyne mirror from another band, though.) What is this? I don't have an SDR or other ham equipment, this is just a mic recording.

I thought it could be useful to drive mice out of a garden shack but it was gone the next day.

_dev_null 3 points 3 years ago

My guess is a cap gone wild in some tank circuit, hence the timed sounds (cap charge/discharge cycle).

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ChaoticNeutralCzech 3 points 3 years ago

Probably not, tank circuit (aka LC resonant circuit) capacitors are low capacity and charged/discharged at the carrier frequency, not every second. And those are pretty reliable kinds of capacitors (polypropylene, usually).

Are you suggesting my receiver is defective? I think it isn't, I was able to pick up a Hungarian MW station (otherwise AM has been shut down in Central Europe).

The audible sweeps seem to be purposefully coordinated, each is shifted by a constant amount. And why would anyone be broadcasting a 5300 Hz beep? (Or a pure sine wave at two frequencies separated by 5300 Hz, which AM receivers would interpret as this beep.)

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