[AMRadio] UTC LS-51

Mike Dorworth, K4XM k4xm at arczip.com
Tue Nov 21 12:50:46 EST 2006

LS-51 push pull low level plates to multiple line

primary impedance 30000 plate to plate. secondary 50,
125,150,200,250,333,500/600 ohms plus/minus 1 db from 10 to 40000 hz.
Max level +24, relative hum -74 db unbal dc in primary ONE ma.

----- Original Message ----- 
From: "A.R.S. - W5AMI" <ars.w5ami at gmail.com>
To: "Discussion of AM Radio in the Amateur Service"
<amradio at mailman.qth.net>
Sent: Tuesday, November 21, 2006 12:37 PM
Subject: [AMRadio] UTC LS-51

> I need a little help with this transformer.  It is a UTC LS-51 in my
> 1937 speech amp.  The output tubes are a pair of 56's in push pull
> connected to pins 7 and 10, and the output is line level at I'm
> assuming around 500 ohms balanced using pins 1 and 6.
> Does anyone have a diagram of this transformer with specs on the pins?
>  I think I may have a some shorted turn on one side of the primary, as
> my audio p-p voltage shows one side about half of the other, but I
> just want to make sure the thing is connected right first.  I tried
> swapping the 56's, but the same side showed a reduced audio voltage.
> tnx
> Brian / w5ami
> -- 
> "There is nothing more uncommon than common sense." -- Frank Lloyd
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