Before I get to the results, I need to make a few things clear:
Air tests are just that, tests. This is not the "end all and be all" of performance as many factors in the ground can change these numbers in a NY minute. I ask that, anyone, that replies, please do not give the "forty minute" lecture on why air tests don't mean anything. If you don't know anything about depth tests of any kind, then please look elsewhere to "study-up" before reading this post.
Also, I do my air tests repeatedly to make sure I get the most accurate data as possible. Is it exact? No! It's ballpark give or take 1/4 of an inch. What I qualify as a "hit", is a two way slightly repeatable with a clear waver in the threshold.
test date 5-29-15
Sensitivity 10/90/90 5 hz band pass d-dime n-nickel q-quarter all numbers are in inches
10" D2 coil
3F
d-10
n-11
q-12
2.5khz
d-11.5
n-8
q-14.5
7.5khz
d-11.5
n-11.5
q-13.5
22.5khz
d-11
n-13
q-14
4x6 shooter
3F
d-7.5
n-8
q-9
2.5khz
d-8.5
n-7
q-10
7.5khz
d-8
n-8.5
q-9
22.5khz
d-8
n-9
q-9
Observations:
Compare the 3 Frequency to single frequency. Single gets more depth(most probably know this).
Next, note the lost of depth when switching to the smaller coil(To be expected)
10" D2
3F
d-10
n-11
q-12
4x6 shooter
3F
d-7.5-loss of 2.5 inches
n-8-loss of 3
q-9-loss of 3
Notice also on the 10" D2, the "velocity of depth gain/loss(VOD G/L)" on the nickel(low conductors) when switching frequencies. Depth gains of up to 5 inches! Compare that to the 4x6 shooter where the VOD G/L is about .5 to 2 inches.
10" D2
n-11-3F
n-8-2.5khz
n-11.5-7.5khz
n-13-22.5khz
Note the 5 inch gain on the D2 from 2.5khz to 22.5khz on the nickel above. Higher frequencies hit better on low conductors but...
4x6 shooter
n-8-3F
n-7-2.5khz
n-8.5-7.5khz
n-9-22.5khz
Where is that HUGE gain on the smaller coil? It's reduced to a 2 inch gain. We can conclude here that, the larger the coil and the higher the frequency, the more depth you can get on low conductors(is that why all those gold PI machines have such big coils
) But, is the inverse true(in relation to coil size and frequency)? Will lower frequencies on smaller coils hit deep on high conductors? Let's take a look.
10" D2
2.5khz
d-11.5
q-14.5
4x6 shooter
2.5khz
d-8.5-2 inch loss
q-10-4.5 inch loss
Nope, not even close. A 2 inch loss on the dime AND a 4.5 inch loss on the quarter.
So, I just bought the 4x6 shooter. Should I throw it out because it not good for deep coins(Rhetorical question)? Also, 11.5 inches on a dime. Is that the best this machine can do in an air test(Also, a rhetorical question)?
We will find out in the next installment
(DUN DUN DUUUUUNNNNN!!!!!)
Bey
Air tests are just that, tests. This is not the "end all and be all" of performance as many factors in the ground can change these numbers in a NY minute. I ask that, anyone, that replies, please do not give the "forty minute" lecture on why air tests don't mean anything. If you don't know anything about depth tests of any kind, then please look elsewhere to "study-up" before reading this post.
Also, I do my air tests repeatedly to make sure I get the most accurate data as possible. Is it exact? No! It's ballpark give or take 1/4 of an inch. What I qualify as a "hit", is a two way slightly repeatable with a clear waver in the threshold.
test date 5-29-15
Sensitivity 10/90/90 5 hz band pass d-dime n-nickel q-quarter all numbers are in inches
10" D2 coil
3F
d-10
n-11
q-12
2.5khz
d-11.5
n-8
q-14.5
7.5khz
d-11.5
n-11.5
q-13.5
22.5khz
d-11
n-13
q-14
4x6 shooter
3F
d-7.5
n-8
q-9
2.5khz
d-8.5
n-7
q-10
7.5khz
d-8
n-8.5
q-9
22.5khz
d-8
n-9
q-9
Observations:
Compare the 3 Frequency to single frequency. Single gets more depth(most probably know this).
Next, note the lost of depth when switching to the smaller coil(To be expected)
10" D2
3F
d-10
n-11
q-12
4x6 shooter
3F
d-7.5-loss of 2.5 inches
n-8-loss of 3
q-9-loss of 3
Notice also on the 10" D2, the "velocity of depth gain/loss(VOD G/L)" on the nickel(low conductors) when switching frequencies. Depth gains of up to 5 inches! Compare that to the 4x6 shooter where the VOD G/L is about .5 to 2 inches.
10" D2
n-11-3F
n-8-2.5khz
n-11.5-7.5khz
n-13-22.5khz
Note the 5 inch gain on the D2 from 2.5khz to 22.5khz on the nickel above. Higher frequencies hit better on low conductors but...
4x6 shooter
n-8-3F
n-7-2.5khz
n-8.5-7.5khz
n-9-22.5khz
Where is that HUGE gain on the smaller coil? It's reduced to a 2 inch gain. We can conclude here that, the larger the coil and the higher the frequency, the more depth you can get on low conductors(is that why all those gold PI machines have such big coils
) But, is the inverse true(in relation to coil size and frequency)? Will lower frequencies on smaller coils hit deep on high conductors? Let's take a look.10" D2
2.5khz
d-11.5
q-14.5
4x6 shooter
2.5khz
d-8.5-2 inch loss
q-10-4.5 inch loss
Nope, not even close. A 2 inch loss on the dime AND a 4.5 inch loss on the quarter.
So, I just bought the 4x6 shooter. Should I throw it out because it not good for deep coins(Rhetorical question)? Also, 11.5 inches on a dime. Is that the best this machine can do in an air test(Also, a rhetorical question)?
We will find out in the next installment
(DUN DUN DUUUUUNNNNN!!!!!)
Bey
