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Can you enlighten us how you performed the surgery, type of glue and how you terminated it for the low end response? Thanks and 73 de k7iou
The Metal Diaphragm can be removed by melting the tar in the center thereby releasing the "anvil" from the diaphragm. The outer circumference of the diaphragm is then detached from the plastic housing by carefully slipping the sharp point/edge of a scalpel in between them. The adhesive on mine was brittle due to age, and by carefully using a prying/slicing action the separation was completed. Damage was minimal and could be compensated for by using silicone upon re-attachment.
The Rachelle Salt Crystal is located on 2ea pads "glued" to the plastic housing at opposing corners of the crystal via some kind of tar. The "anvil" was then attached to the opposite opposing corners of the crystal using what looked like some kind of acrylic enamel. It was detached in my element, so I reattached the "anvil" using some red nail polish making sure that the bottom hooks of the "anvil" or the adhesive did not touch the plastic housing. You must also make sure that the top tab on the "anvil" will be located in the center hole of the metal diaphragm when re-attached.
Once the nail polish has set and dried, the metal diaphragm can then be prepared for re-attachment by applying a thin coating of silicone adhesive around the circumference. Re-attach the diaphragm to the plastic housing while centering the tab of the anvil into the center hole of the diaphragm making sure it does not touch. This will keep from applying any type of side load on the crystal. Press around the circumference of the diaphragm to seat the silicone being mindful of the center hole & tab. Allow to fully cure.
Once the silicone is fully cured, you can then remelt the tar in the center thereby reattaching the anvil to the metal diaphragm.
For the impedance matching in my application, I am using a Jfet circuit to match the high impedance crystal element to a low impedance mic amplifier circuit in a rice box. There is much information available on this subject and I won't go into it here. You can build it yourself, or you can buy one. I chose to buy one already on a circuit board due to ease of installation, it was inexpensive, it can be easily removed/bypassed to use the mic in other applications.
The design I am using was created by Paul, W9AC and in my opinion is very good to say the least.
http://www.qrz.com/db/W9AChttp://www.ebay.com/itm/Astatic-D104-High-Performance-FET-Amplifier-/231424130918?pt=LH_DefaultDomain_0&hash=item35e1f3ff66Take Care,
