Been using both the White TDI Sl and ML Xterra 705 with 5x9 coils here in the California Mother Lode and along the Klamath and Trinity Rivers. Between the two detectors been able to handle the ground conditions. Lots of magnetite. Use the TDI Sl over the serpentine. Heavy thick brush, steep terrain, occasional old cabin and tent sites from 1850 through the Depression Era into 1950's. The smaller coils are a must, just can't sweep the larger coils on the steep brushy slopes. Been looking at the Fisher F19 and F75 which both seem comparable to the Xterra 705. Like the option of searching for coins & relics while detecting for gold when an old camp site is discovered.
After reading several of Steve's articles on the Fisher Series and Xterra, here is what I think I have learned:
The F19 at 19 kHz and Xterra 705 are very close except the Xterra multi-frequency coils selection ( 3, 7.5 & 18.75 kHz); the only waterproof Xterra coils is the 6"; all Fisher coils are waterproof. Not sure if the F19 displays discrim target id in true all metal mode; the Xterra 705 does not. The F19 is a little pricey compared to the Xterra 705.
The F75 at 15 KHz 13 kHz in true all metal mode will indicate discrim target id. The Xterra 705 does not display target Id in the prospecting true all metal mode; requires you to toggle over to Coin/Relic Discrim mode for target id resulting in a loss of detecting depth. The F75 Discrim notching is limited compared to the Xterra 705. The F75 apparently has a history of EMI problems; the Xterra does not. The Xterra with a 18.75 KHZ coil runs a little hot for coins and relics but works. The F75 apparent ability to separate out good targets in trashy areas may be a big plus over the Xterra. The F75 stock coil ( 8x11?) may work in the brush. The current base F75 and Xterra 705 price are the same; the F75 Limited Editions $ 250 plus higher.
Often switch from Prospecting mode and use the Discrim notching feature on the Xterra 705 then toggle between the notch and all metal to weed out the iron using target id when in trashy old mining camps. ( Use the Garrett AT Pro in pro mode when strictly coin/relic hunting; great target separation; iron audio; but no true all metal mode for prospecting.) Do not know enough about the F75 Limited Edition Boost/ Cache features to decide if they will be useful. Use the TDI Sl detecting for nuggets under a gram so the Fisher F75 15kHz is not an issue. Really like the F75 feature of displaying discrim target id in the true all metal mode; current pricing on the base F75 with two coils at $599 is hard to pass up.
Have drop the F19 from the list. Any opinions and experience with the Fisher F75 compared to the Minelab Xterra 705 are welcomed. Keep in mind on the west coast during the gold rush US coins were in short supply; some military buckles from the war with Mexico were exchanged for trade goods. Let me know what you think and keep Santa out of this; on the wrong list.
Good prospecting & detecting
To all you devil dogs out there, have a Merry Christmas where ever you may be. Semper Fi