robert440 wrote:
At one point I did play with creating a dynamic version of the D104, but the
project never flew.

Imagine my chagrin. I just took apart my D104 to check the markings on
the dynamic element I was sold in the '70s. It says MC-320, which,
according to a quick web lookup, is a crystal element.
blush

This may be a good time to install that Heil element...
--
St. John
Utility is when you have one telephone, luxury is when you have two,
opulence is when you have three -- and paradise is when you have none.
-Doug Larson