That "whatever" that a dealer somewhere has advertised: If it's at 71 kHz, it's a Gold Bug II. If it's not a Gold Bug II, it doesn't run at 71 kHz. If it was made in El Paso. If it's actually a Chinese fake, then who knows what is or ain't?
The new Gold Bug and its derivatives are multipurpose machines running at 19.2 kHz. Jacked up to 71 kHz it wouldn't be any good for coinshooting and would be of questionable value even for relic hunting. So it ain't happ'nin'.
In another thread someone asked if the "old Gold Bug" searchcoils will work on the new Gold Bug, since they're both 19.2 kHz. The answer is no-- different electrical characteristics, different connectors.
Someone also asked again if the Tek "Frat Bros." concentrics will work on the new Gold Bug, since the DD's will. The answer is "only if you get lucky". The Gold Bug is designed specifically to work with DD's without any attempt to accommodate concentrics. The concentrics either won't work or are very marginal.
It has been reported that an SEF accessory coil (as I recall a 12x10) is now available for the "Greek Teks". Since SEF's are basically DD searchcoils, there's a good chance they may also work on the Gold Bug platform products. However without having examples in my hands I cannot say anything definitive about them.
--Dave J.