[R-390] Z503

[Gordon Hayward]

My Z503 was open so I replaced it with a 1.5 mH adjustable coil and a 56-pF capacitor (both from my junk box).
The trick was to use as big a coil and as small as a capacitor as possible to get a high Q.  Beware of too small
a capacitor because of stray effects.  I put them in the original can, so it looks original.   It now works as
specified in the manual.  You can use something like this if you can't find a replacement.