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Hello Andy
The idea of using any SMPS in, or near, the shack is somewhat
abhorrent. It is possible to introduce a series circuit in a linear PSU which is
not exactly a regulator but has a hum cancellation circuit, something that used
to appear in an ancient National Semiconductor publication. I'd love to try it
but just haven't left any room in my PSUs, they're stuffed full, including a
cooling fan. A couple of 100Hz side bands are at least predictable, my PA has,
but there is one regular transmission on LF which has all manner of spurii
making reception here somewhat variable.
I think Dave, GW8GLO, has a system which promptly knocks off his
transmitter SMPS when going into Rx mode, maybe this is the way to go.
73, Hugh, M0DSZ
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Receiving the following content -----
Time:
2017-10-23, 10:12:17
Subject:
Re: Re: LF: MF/160
Its a difficult call - I have a similar problem with my 700 Watt
137kHz Tx. 30dB hum sidebands corresponds to 3% ripple, which in the main
scheme of things is not that much. It would need an enormous reservoir
capacitor to make a serious reduction.
Either that or design the Tx to run from 50V and use a SMPSU instead of
raw rectified AC
Andy G4JNT
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