Whites TDI SL Or Whites TDI Beachhunter?

[GB_Amateur]

Always a good starting point is Steve's detector database.  Here is the entry for the TDI/BH.

Comparing with the TDI/SL, the non-changeable coil has already been mentioned.  Note the weight (5.2 lb for the BH vs. 3.5 lb for the SL).  Although most of the controls seem to be the same, I don't see the conductivity switch on the BH.  I have the TDI/SPP model (an SL missing the conductivity switch and missing the adjustable delay -- locked at its minimum value of ~10 microseconds).  According to the SL manual, putting the conductivity switch in either hi or lo makes the detector slightly less noisy than in the 'all' position, but if your brain can tell between hi and lo (pretty easy) and can deal with the more signals (think hear all just like an IB/VLF without any discrimination threshold or notching), a lack of the conductivity switch shouldn't be too big of a deal for coin and jewerly detecting, IMO.

It seems the waterproof capability is the big difference, leading to the heavier weight, non-changeable coil, and missing(?) condictivity switch.

Although in general covering a detector control box in a plastic bag risks overheating, assuiming there is no special heat transfer path on the BH then hermetically sealing the TDI/SL control box is likely no different -- apparently making that OK to do.