[ARC5] Transformer Hum

[Richard Knoppow]

      Mechanical buzz is often caused by loose laminations.  If this is 
an open transformer try tightening the bolts that clamp the laminations.

On 3/10/2015 7:51 PM, hwhall at compuserve.com wrote:
> Transformer noise is often from moving parts. (Yeah, transformers aren't supposed to have moving parts.) Normal magnetic fields in the windings can sometimes cause one or more turns to "wiggle" a bit and can also cause core laminations that aren't tightly secured to buzz. You didn't mention how loud the hum was.
>
> I used to listen to one of my CW transmitter power transformers hum as a sort of sidetone. With key up there was a mere whisper of a hum from the supply and with key down the volume of the hum went up. Seemed to be normal operation and never caused any problems.
>   
>
>   Wayne
> WB4OGM
>
>   
>
> -----Original Message-----
> From: Robert Eleazer <releazer at earthlink.net>
> To: arc5 <arc5 at mailman.qth.net>
> Sent: Tue, Mar 10, 2015 8:06 pm
> Subject: [ARC5] Transformer Hum
>
>
> I had a transformer for some lights fail at home so I started going though a
> pile of unknown transformers to see if one would do the job.  A nice big hefty
> one had two black wires and three red wires; two of the red wires had stripes. I
> decided that the back wires, with a DC resistance of about 45 ohms, were the
> primary and the red ones a center tapped secondary.
>
> I hooked up my Variac and
> found that the secondary voltage came right on up, topping out at 194V with 120V
> on the primary - but just before it maxed out, the transformer started
> humming.
>
> Would y'all take the humming as an indication the transformer
> voltage is too high?  In any case I was looking for one with a 12VAC output, so
> it won't do anyway.
>
> Thanks,
>
> Wayne
>
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL