[R-390] Second R-725 on ebay
David C. Hallam
dhallam at rapidsys.com
Sat May 9 14:33:19 EDT 2009
The magnetic shielding properties of Mu metal are very sensitive to cold
working such as bending, etc. I believe Mu metal shields were annealed
after forming to obtain maximum effect.
David
KC2JD/4
ToddRoberts2001 at aol.com wrote:
> Hi All,
> It looks like a true R-725 has a mu-metal shield added around the outside
> of the round PTO shield
> can. Does anyone know if it really makes a difference in the performance of
> the PTO?
>
> I know mu-metal shielding is added around small audio transformers to
> reduce the
> chance of any hum pickup. Is the R-390A PTO susceptible to hum pickup from
> the
> power transformer next to it on the underside of the chassis?
>
> I see it looks like there is some kind of added transformer next to the
> regular power
> transformer on the underside also on the R-725?
>
> If adding a mu-metal shield is beneficial there are places that sell
> mu-metal foil that
> one could wrap around the PTO can.
>
> 73 Todd WD4NGG
>
>
>
>
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