[Boatanchors] CalRad Microphone

[Dave Roscoe]

Once again I will beg some audio expert here on the List, to share their knowledge.  I have an old CalRad DM-17 Dynamic Mike.  It is marked  50K / 50 ohm dual impedance . I cannot see any way to switch the impedance setting. There is a transformer piggybacked to the element, and a switch that seems to short the element in the "OFF" position.  Can anyone share any info that they may have for this ?

73  de Dave W1DWZ