.
> Nope, it can't get there that way. Nothing can get "thru" the chassis
> plate.
>
> 73
> Gary K4FMX
A screw can. Head on one side and the other side into a doorknob cap or a
solder lug. Proof of JI's statements is the use of plated thru holes on
printed circuit boards, especially when run at RF. Look at all the effort
used in wrapping the edges in copper tape and then still having to use
plated thru or wire inserted holes to get the circuit to work.
Carl
KM1H
>> -----Original Message-----
>> From: David Cutter [mailto:d.cutter@ntlworld.com]
>> Sent: Friday, March 19, 2010 2:58 PM
>> To: garyschafer@comcast.net; dezrat1242@yahoo.com; amps@contesting.com
>> Subject: Re: [Amps] placement of RF choke bypass cap.
>>
>> Following logically from what you both say, my guess is that the load
>> capacitors are fed with current via a nut and screw or the like. The
>> current running from one surface of the chassis, via the screw head,
>> along
>> the surface of the thread to the nut and connection on the other side to
>> the
>> caps. Or have I got all wrong?
>>
>> David
>> G3UNA
>>
>>
>>
>> > >>
>> >> >
>> >> >What do you think happens when you use a tube for an antenna
>> element?
>> >> >The whole element is charged. If you connect the feed line to only
>> the
>> >> front
>> >> >side of the element there is still current on the back side of it.
>> >> >How do you think the current gets around to the other side?
>> >> >
>> >> >But try to measure the current on the inside of the tube. You will
>> find
>> >> >none!
>> >>
>> >> REPLY:
>> >>
>> >> You raise an interesting question about current in a tube as opposed
>> >> to a solid rod. In a sire or solid rod, the skin effect current is
>> >> only present on the skin. In a tube however, I'm not so sure there is
>> >> no current on the inner surface of the tube because that is also a
>> >> skin. The issue is complicated because any skin current on the inside
>> >> of the tube also "sees" the other side of the tube, unlike with a
>> flat
>> >> sheet where there is no other side. So that issue remains to be
>> >> proven.
>> >>
>> >> Because a sheet has two "skins", and has no other side like a tube
>> >> does, current flows on both "skins" of a sheet because it is repelled
>> >> from the center. When one drains off current from one skin, the
>> >> repulsion no longer exists and it is immediately replenished by
>> >> current from he other side. Otherwise my load padder caps would not
>> >> be connected to my load variable cap.
>> >>
>> >> Fascinating discussion.
>> >>
>> >> 73, Bill W6WRT
>> >
>> > Bill,
>> >
>> > My point is that there is no difference between the current on the
>> outside
>> > of a tube verses the current on your flat bar or a solid rod.
>> >
>> > Each skin acts independently of the other. One side of a sheet never
>> knows
>> > about the other side as far as current passing thru from one skin to
>> the
>> > other. This is very evident in a tube which has an inner and outer
>> skin.
>> >
>> > Provided the material is several skin depths thick, there is never any
>> > current on the inside.
>> > Not because the current from one side acts against the current on the
>> > opposite side but because the current on the "surface" sets up eddy
>> > currents
>> > just below the surface that oppose each other and cancel the deeper
>> > currents. No current ever makes it to the center of the rod or plate
>> or to
>> > the inside surface of a tube.
>> >
>> > Current does not go "thru" the sheet or rod to get to the other side.
>> It
>> > flows around the edges.
>> >
>> > If current went thru the shield of coax then the coax would not work
>> as it
>> > does.
>> > There is no way for current to enter the center part of a tube or rod
>> or
>> > flat sheet.
>> >
>> > 73
>> > Gary K4FMX
>> >
>
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