20-30 Khz Detectors

[Steve Herschbach]

Well, at 10, 20, 30, and 40 kHz the new coil may just get glued to my Deus shaft. Do you use the 4 or 8 kHz often?

[goldbrick]

 

Typically I hunt in 18 khz when relic hunting. My ears have been trained to the tones in that frequency. Occasionally if pursuing coins I will use 12 khz. If I am in an area containing a lot of degraded cans I may switch to 4 khz.

I have a custom 18 khz program in slot 11 and right next door in slot 12 a 4 khz program that has near identical settings. When I recieve a high tone signal in 18 khz that I think may be big iron, flat iron, or round iron I simply hit one button to switch to my 4 khz program. If the VDI stays the same or goes up it is iron. If the VDI number drops substantially it is USUALLY something non-ferrous. This technique also works well on crown caps. I do not use this technique if hunting a bed of nails.

With the new coil we may be able to obtain similar results using a 20 khz program next to a 10 khz program. The VDI difference may not be as pronounced but hopefully will still be large enough for this to be a viable technique. I have noticed as the months go by and I become more proficient in the use of the Deus I need to use this technique less and rely more on interpreting the tones. There is a lot of info there if one takes the time to really listen.

[PhaseTech]

On 2/23/2016 at 2:22 AM, nvchris said:

One good reason to hang onto or buy used a ML XT 17,000, its 32 kHz " the sweet spot" for gold.

Yeah Minelab must have known something about this many years ago, as the XT17000 and Goldstriker were running on 32 kHz, maybe just out of the troublesome zone for EMI??? I've done a lot of comparisons on the XT18000 in 20 kHz vs the 32kHz Goldstriker, and on most bits the goldstriker hits them so much sharper. BUT, the 60 kHz on the 18000 and Eureka is better again, particular on the 0.1s and smaller, but obviously ground handling suffers. Need to do some comparisons against the Gold Racer at some point 

[Steve Herschbach]

I have fond memories of my XT17000 for sure. The Fisher Gold Strike although it was a market failure actually had very good performance also running at 30 kHz. Obviously the 20 - 30 kHz range is not an absolute no-go zone for detectors.

It is actually a bit funny coming from Dave Johnson in that particular article because the F75 at 13 kHz was one of the most EMI plagued detectors I ever used.

The low single digit frequencies do have superior ferrous handling characteristics and I had read of the Deus trick of shifting to 4 kHz quickly as a ferrous check. Not tried it out myself though, but daffodils are blooming in Reno so time to get with it. Very busy month ahead for me on other things though so unfortunately detecting is still taking a back seat.

[PhaseTech]

In my lounge room, the 15 kHz CoRe chatters away, the 19 kHz Gold + has a slight chatter, 20 kHz 18000 is totally quiet, 60 kHz goes bonkers, 56 kHz Gold Racer purrs like a kitten. Customer just brought in an old Goldmaster II, and it too was quiet as a mouse. 

F75 I tried a few times in different areas. One suburban park it was going nuts. Turned the CTX3030 on (which theoretically should be worse) and it wasn't affected at all. In the same spots that drove the F75 crazy, I can use the Fors CoRe without a problem.