I just picked up an old Bounty Hunter II in like new condition. This is one of their early BFO’s. I am wondering if they had faraday shields on their coils. I can put the coil on my hand and I don’t notice any effect but if I wrap my fingers part way around the coil (its an open loop) it has a nulling effect. The coil is inside a potted body so I’m not physically deforming the coil. I notice a similar but much less noticeable behavior when doing the same test on my home made BFO on which I implemented a wrapped aluminum foil shield. But on that one the coil is not potted. It is only taped so I’m sure I’m compressing the coil a little.
The Bounty Hunter almost certainly is shielded or it would react to my hand when just getting close. It seems ok until I wrap my fingers part way around it.
Is the shielding just not good enough or what?
Is there a shielding technique that will totally eliminate the capacitance effect of wrapping my fingers around the coil?
Well......just as I was typing these questions I had a thought to test something. I put my hand across the bottom of the coil and there was little to no effect. I put my hand across the top of the coil and it nulls. They only shielded the bottom! I guess they used a carbon sheet or some other flat shield on the bottom? I guess it’s cheaper and easier to manufacture that way.
I guess I answered my own question but maybe it’s interesting to someone so I’ll leave it here. lol.
The Bounty Hunter almost certainly is shielded or it would react to my hand when just getting close. It seems ok until I wrap my fingers part way around it.
Is the shielding just not good enough or what?
Is there a shielding technique that will totally eliminate the capacitance effect of wrapping my fingers around the coil?
Well......just as I was typing these questions I had a thought to test something. I put my hand across the bottom of the coil and there was little to no effect. I put my hand across the top of the coil and it nulls. They only shielded the bottom! I guess they used a carbon sheet or some other flat shield on the bottom? I guess it’s cheaper and easier to manufacture that way.
I guess I answered my own question but maybe it’s interesting to someone so I’ll leave it here. lol.
