[R-390] R-390A power transformer hum

[Tom Frobase]

Some are noisier than others.  I have a large supply here if you want to
replace it.  Contact me offline ... tom, N3LLL

On Sat, Oct 19, 2024 at 8:18 AM Leo Reynolds via R-390 <
r-390 at mailman.qth.net> wrote:

> Is it normal for a R-390A power transformer to hum audibly? Not through
> the speaker, though there is a little there too, but through slight chassis
> vibration. It is there from the instant of turning on power and changes
> slightly as the rectifier starts conducting and B+ flows. It is easily
> audible in the shack, as if it were a small AM broadcast transmitter minus
> the blower.
>
> Thanks,
>
> Leo Reynolds
> K4LDR
>
>
>
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