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Actually foam, being mostly air, would be better. Another approach would be to drill many holes in the material, leaving a skeletal frame which, again, is mostly air. This is essentially what B&W does

Hi Alan I tried the experiment with a 15 ohm carbon resistor but it didn't produce the expected result. The calculated resistance went up from 7.5 ohm

Hi Brian, I do not pretend to be any sort of expert here, so I have probably missed something vital. But in your 2nd iteration, I notice the coil length is significantly longer (156.8mm vs 80mm) with

All, What about radiation from the coil? Another basic definition for Q relates to the energy stored / energy lost. If energy is lost to radiation that needs to be considered as well. Very interesting

Thank you Roger! Yep, looks like mine's older than that. Sounds like a firmware update will get me fixed up. That menu map is WAY more extensive than what I have. Looking forward to it! Thanks again!

The option was added to the firmware around January 2021. If yours is old update the firmware. Lots of nice features and bug fixes over the years.

Well, I see the Polar/Rect menu options, but I don't see anything about the nature of the reactance display. Mine must be from before they added that. What hardware and firmware do you have? (No rush,

Thanks.

Hi Roger- Thanks very much! I had looked for that and didn't find it, but I'll look again. Mine's pretty early. Might have been added between the time mine was made and yours? Thanks again... Back to

Rules of thumb are handy, but today it's easy to directly optimize a coil design. The first image show's Mike's coil. The second shows it after optimizing turns and coil length. The third is after

Hi Mike. I suspect that the dielectric loss of your coil is secondary. A Qul of nearly 350 implies to me that the primary losses are likely copper wire R and fixture. A couple of useful things to do.

No I wouldn't use black for that reason. It's white (see photo further up this thread). It's solid, not foam. -- Mike

Ohh. Black ABS? As in Drain Waste Vent (DWV) pipe? The black is from carbon black as a pigment - yeah, as in resistors Also, most DWV is what is known as "cellular" which means that the walls are

After all that debate about PVC I've just discovered that my coil former is actually ABS ... Apologies! -- Mike

Thanks for all your comments, Jim. I think I've seen different dissipation factor values for PVC depending on filler amount. I believe I used values for pure PVC, but I can't remember. In any event,

On Tuesday 04 July 2023 02:54:32 pm Jim Lux wrote: > On 7/4/23 11:16 AM, WB2UAQ wrote: > > Mike and Alan, > > I measured the loss factor for PVC and it was about 0.005 or so at 1 kHz. I did more

On 7/4/23 12:24 PM, Brian Beezley wrote: > On Tue, Jul 4, 2023 at 11:54 AM, Jim Lux wrote: > >> >> PVC pipe has two potential problems as a coil form (based on experience of >> folks building tesla

Just 4 turns. The idea and constructive details came in 2015 from Jim Giammanco N5IB, the original designer of the PHSNA. Ignacio

I asked Google AI whether PVC is hygroscopic. Here, in part, is what it said Polyvinyl chloride (PVC) is a hygroscopic powder material. Hygroscopic substances can take and hold moisture from the

On 7/4/23 11:16 AM, WB2UAQ wrote: > Mike and Alan, > I measured the loss factor for PVC and it was about 0.005 or so at 1 kHz. I did more measurements at RF but will have to go back to old note books.