I note that Collins mics are typically specified as having -50 dB output but what is the reference voltage level and is the mic output specified open cct or loaded-if so, with what? 73 Dave, ZL3FJ -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.407 / Virus Database: 268.13.1/466 - Release Date: 7/10/2006