[R-390] Z503 Replacement

[Tisha Hayes]

Randy makes a great point. None of the constituent components that make up a
coil form have the same coefficients of expansion due to heating/ cooling.
If you mechanically stress any wire it will eventually "cold work" at a
stress point and fracture.

It is not as if these receivers have never been exposed to vibration,
dropping, hot environments or transient voltages. There have been problems
in the past with the power and audio transformers where the wax/asphalt/tar
hardens and eventually the transformer fails.

We are all doing things to pieces of equipment that are well beyond their
design lives. Obscure failure mechanisms will begin to pop up. Another
example of that is the gooey mess that the foam inside of the mechanical
filters turns into.

Then again, sometimes "stuff" happens. The particular failure of this one
inductor does not seem to be a widespread problem that we all are
experiencing. If we dedicated as much effort into the analysis of every
single component in the receiver as we have to Z503 then we have at least
another 30 years of discussions to hold.

It was interesting to see how folks figured out the L, C and Q values of
Z503. We have even bounced around the ideas of why the Q should be where it
is at. All great discussions but at the end of the day, 85% of us who may
have a failure of Z503 will just pull one off of a junker IF deck that are
flooding the auction sites.

-- 
Ms. Tisha Hayes/ AA4HA
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*“If toast always lands butter-side down, and cats always land on their
feet, what happens if you strap toast on the back of a cat and drop it?”
Steven Wright

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