Not with your average HF mobile antenna you can't.
The voltages can be very high, in the neighborhood of 10 KV even at low power levels. If you try this with a hamstick or Hustler, you'll end up arcing over the coils.
If you go to my web site and look under Auto Couplers, all of the data you need is there.
Alan, KØBG
www.k0bg.com