Other ways of introducing an air gap to signal transformers

By interleaving laminations not 1 by 1 but by say 7 Es then 7 Es in the other direction.


This was suggested by Brian Sowter years ago as a way of reducing winding inductance. It has been used on a input transformer connected to the Coles 4038 in order to compensate for the proximity effect.


This nice technique was read today on the great book [Lee].


Quoting:
"There is always a certain amount of gap even with punchings stacked alternately in groups of 1. Table VIII gives the approximate gap equivalent of various degrees of interleaving laminations for magnetic path lc of 5.5in."


Reference:


Electronic Transformers and Circuits - Reuben Lee - Wiley - 1947 - Linear Reactor Design - page 75