Mercury United Electronics has been manufacturing quartz crystals, clock oscillators, TCXO, VCTCXO, VCXO, OCXO, and monolithic crystal filter frequency control products since 1973. MERCURY Electronic Ind Co., Ltd. Mercury continues to satisfy the needs of the market via the development of numerous innovative and advanced products as a pioneer in the crystal sector. Many of these items with great accuracy fulfill very tight and exact requirements and are also available in tiny mounting surface packages. From the low KHz to eight hundred MHz, frequencies vary.