D-104 element resistance

[stevef]

In the course of dismantling and cleaning up a D-104, I thought I'd check the mic element.  It shows an open circuit.  What should the resistance be ?  The element is an MC-??0 (part of the writing is worn away).  I have not tried this mic on a radio yet.

[k4kyv]

A crystal mic will read open with an ohmmeter.  The element consists of a small plate of rochelle salt crystal sandwiched between two conductive plates, one of which is mechanically linked to the diaphragm of the mic.

For best low frequency response, the mic should work into a load resistance of 5 megohms or more.

Careful how much voltage you apply to the xtal element!  The xtal will flex with voltage.  Too much might shatter the xtal plate.  I understand that the replacement D-104 xtal cartridge assembly has been discontinued and is no longer available from the manufacturer.

[Jim, W5JO]

  I understand that the replacement D-104 xtal cartridge assembly has been discontinued and is no longer available from the manufacturer.

The element is still available through Astatic a division of Omnitronics.  The bad news...they won't sell the element, you must send the head to them and they replace it for your.  About 40 dollars or so which includes shipping back.

[Ed KB1HVS]

http://cgi.ebay.com/NEW-1-INCH-CRYSTAL-MIC-ELEMENT-HI-Z-12K-OHMS_W0QQitemZ7382602166QQcategoryZ15198QQssPageNameZWDVWQQrdZ1QQcmdZViewItem 


http://cgi.ebay.com/ASTATIC-D104-REPLACEMENT-MIC-MICROPHONE-ELEMENT_W0QQitemZ5855146238QQcategoryZ48707QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 Would these be of any use?