While the input impedance of the low input is 50 ohms if 10 dB internal attenuation is added, without an external attenuator the impedance of the high input will vary. Filters and attenuators can be obtained from RF component manufacturers like Mini Circuits and added externally.

The first thing to know is there is no filtering on this input and no internal attenuation. I know many, if not most, readers will be interested in how it performs using the “free” high input that covers from 240 MHz to 950 MHz. Frequency accuracy is specified as the selected resolution bandwidth, which can be set to 3, 10, 30, 100, 300 or 600 kHz or set to “auto.” Not bad for $50.

Spur-free dynamic range is 70 dB at that resolution bandwidth. With a resolution bandwidth of 30 kHz it can detect signals down to –102 dBm. It includes a built-in level calibrator for this input and after calibration specified accuracy is +/–1 dB. The tinySA low input for frequencies below 350 MHz has filtering and adjustable attenuation in 1 dB steps between 0 dB and 31 dB. TinySA size as compared with USB tuner (Image credit: tinySA)