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Well, it all depends on what you are looking for? There are three frequencies available: (1) Low, (2) Medium & (3) High.
The Low Frequency of 3kHz would be well suited to searching out metals of a high conductivity such as copper and silver coins. It might be considered a good cache hunting coil. Useful also in hunted out parks for deeper silver coins which are masked by trash items.
The Medium Frequency of 7.5kHz is a great ‘all-rounder’ and encompasses the entire conductive band of all metals from iron to silver. This coil can be used until the proverbial cows come home, but why limit yourself to just one?
The High Frequency of 18.75kHz is suited to searching for smaller targets that would fall into the ‘difficult to detect’ category. These would generally be tiny thin targets and small jewellery made from various gold carat make-up, gold rings and in Europe, small thin low-conductive ancient objects and medieval silver coinage. However, there is a slight drawback using the higher frequency coil, as it can cause more ‘eddy current excitement’ in rusted iron objects.
Some of the coils available for the X-TERRAs can go deeper than others. For example, the larger 10.5” coils (7.5kHz Double-D & 18.75kHz Double-D) can go deeper than the standard 9” stock coil and appears to be a great favourite of searchers all over the world. There are also coils which search to a more moderate depth (but still to several inches for single coins) and here the two small 6” coils (7.5kHz Concentric & 18.75kHz Double-D) are great! There’s even a High Frequency choice for gold prospectors who like to do ‘Double Duty’ with their X-TERRA 705 detector and search out both coins & relics and occasionally go off and seek out valuable small nuggets as well! For this task and for searching in tight spaces such as stubble rows or around tree trunks and beach abutments, the 10” x 5” Double-D High Frequency Elliptical coil is the ‘cat’s whiskers’ of coils to use in these tight constricted spaces.
One of my favourite coils is the small 6” High Frequency Double-D coil with which a lot of my jewellery recoveries are made with… and it is waterproof too (Check the coil selection guide to see which X-TERRA coils are waterproof).
So go on, try one on and see what gives? I’d be willing to bet your finds rate is going to go up! More frequencies = more finds.
The X-TERRA 705 is amazing on the shingle beach using the standard fit coil, it is very good in trash but a little less stable than the E-TRAC near water.
I have had a lot of success in the last week with it and have found over £200 last week alone.
Tip for the next version, E-TRAC tones and 2 sets of numbers like the E-TRAC.
Many thanks for taking the time to read my blogs and adding your very positive comments.
All points noted.
frank63, I would suggest you suit the coil to the site and not to believe that any one of them "is best to use!"
Truth is, they are all "best to use" because we designed them to perform as well as each other BUT, you would have to suit the coil to the site!
Let's say a person asked if you would search their yard to find a lost ring! Go along and gauge the size of the yard - area you would have to cover - if a large yard than a large 10.5" coil would suit and if a recent loss then Sensitivity could be set at a LOW setting
If a small yard then the 9" concentric and the 6"inchers would best suit - 70% Sensitivity on the 9" and 90% Sensitivity on the 6"