Plot accurate antenna patterns -- connect it between you receiver and antenna and use your S-meter as a precision calibrated field strength meter.
Eliminate blocking and cross-modulation by attenuating strong-out-of-band signals before it gets into your receiver. Must be used only in a "Receive" line, not at the output of your transmitter.
Connect it to your receiver input to properly terminate your preselector at all frequencies to insure good out of-band filtering.
Use it to determine gain and loss and to evaluate linearity of circuits. measure input and output level differences. Isolate one circuit from another. Change unknown reactive loads and sources by known levels. Extend the range of sensitive measuring equipment.
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