Valcom's BBMT-50 and BBMT-70 consist of matching transformers or baluns designed to produce a good impedance match between a receiving antenna and 50-ohm and 70-ohm coaxial cables.

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The matching transformer in both units is of a broadband, toroidal design. Normally, the standard BBMT-50/70 is used to match one of Valcom's 35-foot vertical whip antennas to a receiver in the frequency range of 100 KHz to 30 MHz.

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Other antenna heights and configurations can also be matched, but the antenna must be specified so the optimum transformer design can be used. If a narrower frequency range is specified, the matching transformer design is chosen to match the antenna and the receiving frequency range.

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For best receiver performance, the antenna and operating frequency range must be specified so the BBMT-50/70 can be designed to give the optimum matching characteristics.