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N_Cook N_Cook is offline
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Default unkown output impedance measurement?

Henry Kolesnik wrote in message
...
This is in an old military radio which I suspect is not 3.2 ohms but
somewhat higher like maybe 600. It's kind of hard to get to the
primary. I guess I should have stated that at the beginning. I kind of
recall some way of measuring the open circuit voltage from a tone and
then with a pot connected across the output, set the pot to where the
voltage is 1/2 and then measure the pot. Do I have that correct?
Hank
"Michael A. Terrell" wrote in message
m...

Henry Kolesnik wrote:

normal speaker impedance



A low, known AC voltage is applied to the secondary winding, and the
voltage is measured across the other. Be careful, because the voltage
on
the primary winding will be high enough to shock you.

The voltage on the primary over the applied voltage gives you the
turns ratio. Square that number and you have the impedance ratio from
primary to secondary. Since the transformer is in a push-pull
application, the primary impedance is 'Plate to plate'.


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I would go for a set of watty resistors in series, tone source and a DVM on
AC volts, with amp set at low output.
If on some set of resistors of total value of R , the o/p voltage is greater
than with value R+d and R-d , where d is about R/4 then R is the output
impedance. If highest at R-d then go down, in steps, till it peaks, if R+d
is highest then go higher for peak value


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