Re: Re: LF: Microwave oven transformers

["Ken" <ken.h.wright@btinternet.com>]

Hi Alan.
The earthy end of the HV winding should be lifted from earth, and a fullwave 
bridge used .
Ken
73 de M0KHW
----- Original Message ----- 
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, July 15, 2009 2:57 PM
Subject: Re: Re: LF: Microwave oven transformers


> Hi all, I am very please to see not everyone sticks to a 12 volt maximum
> supply voltage
> :-))
>
> One though that occurs to me is that if one side of the MO transformer is
> grounded in oven service........one ought to check that the winding as a
> whole is sufficiently well insulated from ground to stand floating 2kV 
> above
> ground. There may not be the same clearance /insulation on the grounded 
> end
> of the secondary as the intended high-voltage end?? On the other hand it
> might be quite OK. I have a certain cynicism about "consumer designs".
>
> Alan G3NYK
>
>
> ----- Original Message -----
> From: <dl4yhf@freenet.de>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Wednesday, July 15, 2009 2:34 PM
> Subject: Re: Re: LF: Microwave oven transformers
>
>
> These special transformers need the magnetic bypass because a magnetron
> looks (as a load) like a Z diode.
> So they are powered, more or less, with a constant current source rather
> than a constant voltage source.
>
> In other words, the "generator" (transformer) must have a large source
> impedance, and that's what the magnetic bypass in the 'former does.
>
> Cheers,
>  Wolf .