Airspy Discovery (9Khz-31Mhz & 60Mhz-260Mhz)

It is not recommended to connect these antennas to any SDR directly. An RF isolation transformer is required to prevent the destruction of the RF input of the SDR, the USB port of the SDR, the USB port of the PC, or all of them.
Also, the same thing could happen with a Discone or any other VHF/UHF antenna if it is not grounded to the same GND point as the computer. Keeping the antennas “electrically floating” creates static electricity and you get a discharge when you try connecting the RF input or the USB.
Another important parameter to take into account is the RF leakage to the receiver from a powerful TX. The maximum RF power at the input of SDRs should not exceed +10 dBm. Leaving the antenna connected while transmitting in another antenna a few meters away will create more than +23 dBm and can destroy the RF circuitry. A proper antenna switching mechanism should be installed in case of TX.
If in doubt, ask a specialist or ask in our mailing list: https://airspy.groups.io/g/main/messages

Building on the field-proven Airspy HF+ architecture, we designed the Most Refined HF/VHF SDR with world class performance in the smallest form factor.

The Airspy HF+ Discovery sets a new standard in terms of reception performance with extra pre-selectors for all the supported bands and a New DSP Core to optimize the gain distribution and the filtering parameters in real-time and dig deeper in the noise.

Meer info: https://airspy.com/airspy-hf-discovery/