[AMRadio] UTC FN-800 ?

D. Chester k4kyv at charter.net
Tue Feb 26 11:55:14 EST 2008

> Anyone know what a UTC FN-800 might be?  It is a two-fist-sized sealed
> "transformer" with 8 terminals.  I'm guessing "FN" might stand for
> filter-network, but so far I'm not finding any reference to it in the
> online UTC catalogs.
> It also shows an RCA number 8500703-1
> Steve WD8DAS

Or possibly an interstage or driver transformer with split primary and 
secondary windings.

Try taking an ohmmeter to figure out which terminals go to windings, by 
checking out continuity.  Then put a few volts a.c. from a filament 
transformer onto one of the windings, and measure voltage output from the 
other windings to determine turns ratio.  Also, the dc resistance might give 
a clue.  110/200v primary should  show up as 10-15 ohms, a couple of ohms or 
less could be a filament winding or low impedance speaker winding of an 
output  transformer, 100-500 ohms  could be the hv winding of a power 
transformer or an audio winding at a  few thousand ohms, and 500 ohms or 
more would indicate a higher voltage power transformer output or higher 
impedance audio winding.

If you thing it is a filter network, try sweeping with a signal generator 
across the audio spectrum to see what the frequency response is.

Don k4kyv 

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