Link Coupling Position

[W9ZSL]

I've seen quite a few plug in coils of various types on the market lately.  Some have the link coupling at one end and some have it in the middle.  I could wind my own with a coupling on the cold end, but thought it would be more fun to use one of the vintage types for the output of my HB exciter.  What's the difference if any between end and center linkage?

[W1ITT]

It depends on the intended use.  If you are using the coil set in a balanced tuner, or in the output of a push-pull amplifier, the centered link  would be just the ticket to maintain balance.  However, if you were coupling to a single-ended stage, the cold-end configuration is appropriate. 
Either way, a viewing window is called for so that you can enjoy circuit scenery.