I recently acquired a Shure 9898 with a vintage sound meter. Do you have any information you can provide on this mic?
The 9898 was a variation of the model 702L.
From the Shure 1942 catalog:
The Shure model 702L non-directional crystal microphone is designed for scientific and industrial sound measurement work - and for high quality sound reproduction in broadcasting, professional recording, and other applications. High fidelity flat response from 30 to 10,000 cycles in the horizontal plane. Output level 58.3 dB below 1 volt per bar, open circuit. Diameter 2.25 inches. Supplied with 25 foot shielded cable. Satin chrome finish. List Price: $47.50