[R-390] Re: UTC 68819 xfmr

Fri, 13 Dec 2002 20:13:22 -0500

Drew: That's an excellent technique.  I think in this case I'd be inclined
to apply 6 VAC to the 75,000 ohm winding, and measure the other winding.
That way the resultant will be in the millivolt range, and the transformer
won't pull any serious current...

Dave WB4FUR

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Drew Papanek
Sent: Friday, December 13, 2002 1:12 PM
To: [email protected]
Subject: [R-390] Re: UTC 68819 xfmr

Dan,

You can easily determine the unknown impedance from voltage measurements.
Apply an AC signal of appropriate frequency  to the known winding (110 VAC
60 Hz works well for a typical high impedance audio transformer winding).
Measure AC voltage on secondary.  Divide this by primary voltage and square
the result.  This gives you the impedance ratio from which you calculate the
secondary impedance.   I have used 6.3 VAC on a low impedance winding and
measured the resultant on the high impedance winding.  Don't apply high
voltage to a low impedance winding or you'll let the smoke out.

Drew

>Date: Thu, 12 Dec 2002 15:35:49 -0800
>From: Dan Merz <[email protected]>
>Reply-To: [email protected]
>To: R-390 List <[email protected]>
>Subject: [R-390] UTC 68819 xfmr?
>
>Hi,  does anyone happen to know the prim/sec impedance of a UTC 68819
>transformer,  Army #2Z9986-2;  the box is marked  ?50-ohm to 75,000 ohm
>but not legible enough to make out the primary.  It's small unit about 3
>inch high,  thanks,  Dan.

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