[Elecraft] [ELECRAFT] {OT} Transformer to change mic impedance

[David Lankshear]

Hi all.  Has anyone any knowledge of a sub-miniature transformer to change the impedance of a 100k dynamic mic to 600 ohms?

I have a surfeit of old Shure mics and just about all are very high impedance.  Ideally, I'd like a transformer that could be tucked away in a spare corner of a hand-held PTT mic.

Thanks in advance.

Dave, G3TJP