A technician at CCrane suggested that, if I wanted to squeeze more performance out of my Skywave SSB on the HF bands, I might consider attaching a counterpoise to the mini (or micro, not sure) USB port on the side of the radio. Buy a mini-USB cable and pull the center pin out of it, he said, and you are now grounded to the chassis of the radio.

Question: how long should the countpoise be? As long as the whip antenna? As long as any antenna attached to the whip?

Apologies in advance: my knowledge of antenna theory is so limited that "zero knowledge" would be an upgrade for me.