Using the 7.8 / 7.6 kHz coils on the F75

[Mike Hillis]

I do use the 7.8 / 7.6 kHz coils on my F75.

For example, Fisher hasn't yet made the 11" Triangulated concentric coil for the F75. I wish they would as I really like this coil. The 11" Triangulated concentric coil is the stock coil for the F44. I like this coil for when I need concentric coil ability but need more ground coverage than I get with the 10 Elliptical concentric and am ok with the depth limitations that come with it.

Unlike the F75 coils, the 7.8 / 7.6 kHz coils will not provide any modulated audio. Where modulation would kick in on a F75 coils, these coils just quit and go silent. For example a nickel might start modulation around 7 inches on a F75 coil and then via modulated audio still provide a response out ot 12 or 13", however on the F44 coil, it will hit nice and hard out to 8" and then go silent. No additional modulated audio depth is provided. So when I'm ok with a hard hitting audio with a depth limit of 6 to 8 inches, and need the feature of the coil, I'll put these on my F75. They ground balance and work fine within their limitations.

My rule of thumb for these 7.8 / 7.6 kHz coils on my F75 are: 1) Do I need the other attributes of the coil? and 2) Am I OK with 6" of depth? If the answer is Yes to both of these questions then I run the coils.

I can't imagine what the 11" Triangle would do in the F75 if it was designed for it. I bet it would be killer. The 7.6 kHz version is still very sensitive on the F75 on low conductive targets.

The little 4" coil for the 7.8 kKz coil is different, though. It will modulate much like the 5" DD does.

I thought the info might help some of you.

HH
Mike

 

[rick in mi]

It is very interesting. I've burned through different detectors but never centered on different coils. I use the 5" concentric and 11" dd. I'm running the old f75 LTD camo.(with up grades). These coils work good for my type of detecting. Maybe I should try coloring outside the lines of coils.

 

[Mike Hillis]

Yeah..using these coils let me reduce the F75 gain when I need it lower than a setting of 0 will allow. Remember, the F75 only has two gain settings, low and high. And on the F75, low is still quite high. Gain affects the size of your coil footprint. Sometimes I need a smaller footprint than the F75's low gain setting will allow.

The F75 is still a very relevant detector today. A few tricks like this just add to it's versatility.

HH
Mike

 

[rick in mi]

So what are we doing to raise or lower the gain Mike? Raising and lowering the disc? HH Rickinmi