[R-390] Open Z-503 AGC IF Transformer

[Gord Hayward]

>
>
>I am looking for a replacement if anyone has one.  Pulled it apart but it is
>open somewhere inside the windings, usually it is around the connections.
>Anyway, hoping someone can help.  As you know it is not an easy guy to get
>to. ... Tom, N3LLL
>

When I got mine, Z503 was open too.  I tried to steam (hot air really) 
the ferrite off but the whole thing
came undone.  Not finding a replacement, I took a big coil out of my 
junque box, cut the form to fit,
added a resonating cap at 455 kHz and rebuilt the guts of the can.  Now 
its dead on spec.

The trick is to use a small cap, 20 to 40 pf or so to get the Q as high 
as possible.  That circuit needs
the high Q to get the AGC voltage high enough.  Do the resonance check 
before the cutting and
installation steps.

-- 

Gordon L. Hayward, Ph.D., P.Eng.,
Associate Professor, Biological Engineering,
School of Engineering, University of Guelph,
Guelph, Ontaro, N1G 2W1.