determining impedance of modulation xform

Al Parker anchor at EC.RR.COM
Tue Nov 12 13:21:24 EST 2002

hI john,
    Seems to me, that if you take an audio generator, hook it up to the
primary thru a decade resistance box, or switchable resistance, terminate
the secondary with the proper 6500 ohm resistor, and switch the primary's
resistance until you measure the same AC voltage across the primary leads &
the resistor, the resistance will equal the impedance.
    Probably use 1000kc or so, maybe measure with a scope?
Other than that, how are things with you down there?  That's a pretty hefty
xfmr, what ya gonna use it in?
Al, W8UT
New Bern, NC
BoatAnchors appreciated here

----- Original Message -----
From: "john w. king" <jbkking at BELLSOUTH.NET>
Sent: Tuesday, November 12, 2002 11:29 AM
Subject: determining impedance of modulation xform

> Have modulation transformer , potted type, and do not know the
> specifications . It was made by Merit Transformer and looks as if it came
> out of a piece of Military equipment. The impedance of the secondary is
> 6,500 ohms. The impedance of the primary  has been accidentally
> and can't be read.
> The markings are      "PART AM -7195    TEST 10000 V.
>                                       FAMILY 14    GRADE 1    CLASS A "
> It measures  10 1/2 inches high to top of insulators (all on top)
> The width is 5 3/4 inches and the depth is 6 inches.
> It weighs approx 34 pounds.
> Does anyone recognize this modulation transformer? I need to know the
> impedance of the primary winding. If you recognize the transformer or know
> how to measure the primary impedance, PLEASE LET ME KNOW.  I  am trying to
> decide if this modulation transformer will work in my Johnson Viking Desk
> kilowatt.    Thanks for your assistance. 73,John, K5PGW

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