[Boatanchors] output xfmr measurement

[Ian Wilson]

The principle is that if the turns ratio of the transformer (pri:sec) is
1:N, then
  - the voltage across the secondary is N times the voltage across the
primary
  - the current through the secondary is 1/N times the current through the
primary

If you see an impedance Za looking into the primary, the secondary is
connected
to an impedance of Za^2. Alternatively, if you see an impedance of Zb
looking into
the secondary, the primary must be connected to an impedance of sqrt(Zb).

Note that this tells you nothing about the impedance of the transformer
windings
themselves. The assumption is that the reactance of the transformer winding
at the
frequency of operation is much higher than any source or load connected to
the
transformer.

Hope this helps.

73, ian K3IMW


On Tue, Feb 16, 2010 at 3:27 PM, Dick KF4NS <kf4nsradio at verizon.net> wrote:

> Some time ago a friend (now SK) sent to me a brief test method for 'Z'
> of output xmfrs.
>
> It is a bit vague but maybe someone can decipher it. He said:
>
> "Apply 60hz at 1 volt on the secondary and measuring the primary will
> give you the turns ratio. The 'Z' ratio would be the square root of
> the turns ratio".
>
> Can someone give me a mathamatical example of his test? Measuring what
> in the primary and how do you compute the square root of a ratio?
> Guess my math knowledge is a bit hazy.
>
> thanks and 73, Dick KF4NS
> St Petersburg, FL 33714 USA
> Keep The Glow!
>
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>