9732	2014-02-13 19:36:16	Ashhar Farhan	air core toroids
Message	Date	From	Subject
around ten years ago, I started playing around with toroids made from faucet washers (we call them tap washers in India). Looks like someone wrote a paper on these. http://www.engineering.dartmouth.edu/inductor/papers/pesc2007b.pdf - f
9733	2014-02-13 20:54:21	Dave	Re: air core toroids
I wonder how well sch 40 PVC pipe would work. Dave - WB6DHW
9735	2014-02-13 23:01:10	Dana Myers	Re: air core toroids

9736	2014-02-13 23:22:18	ashhar_farhan	Re: air core toroids
Wes did a study of these materials and found the Q to be around 60. I guess, we can measure some teflon cores. I will pick up some teflon next time I am in that part of town. These are particularly useful for vhf work. The regular toroids are useless above 100 mc. - f Sent from BlackBerry®
9738	2014-02-14 01:12:18	kerrypwr	Re: air core toroids
I did some measurements quite some time ago of coils wound on white plastic pipe, the kind that's commonly-used for plumbing and for protecting cable runs; I don't have any information as what it's composition is. It's late here now but I will look in the workshop tomorrow to see whether there is any marking on the length that I still have. The exercise was to compare the difference between inductors wound with solid wire and inductors wound with stranded wire but the results may be of interest in this discussion. Here are two coils, identical save for the wire used; http://i57.tinypic.com/m9yd6v.jpg Here is the measured Q; the red trace is the solid wire and the blue trace is the stranded wire; http://i62.tinypic.com/1109f61.jpg Kerry VK2TIL.
9739	2014-02-14 02:40:52	Leon Heller	Re: air core toroids

9746	2014-02-14 14:21:57	ehydra	Re: air core toroids
You really measured a Q of 180e3 ? I argue that the value is much to high. That the solid wire will show better performance looks ok because in this frequency band it can be expected. Any ideas? PVC losses going high from 100KHz upwards. PE should be better. regards - Henry planningpower@iprimus.com.au schrieb: > Here is the measured Q; the red trace is the solid wire and the blue trace is the stranded wire; > http://i62.tinypic.com/1109f61.jpg http://i62.tinypic.com/1109f61.jpg
9747	2014-02-14 14:31:48	Lasse Moell	Re: air core toroids
:p The always present problem with , and . Looking at the diagram you notice frequency is 0.0000 to 60.0000 So it seems the Q is 0 to 200 in the diagram /Lasse SM5GLC 14 februari 2014, ehydra skrev: You really measured a Q of 180e3 ? I argue that the value is much to high. That the solid wire will show better performance looks ok because in this frequency band it can be expected. Any ideas? PVC losses going high from 100KHz upwards. PE should be better. regards - Henry planningpower@iprimus.com.au schrieb: > Here is the measured Q; the red trace is the solid wire and the blue trace is the stranded wire; > http://i62.tinypic.com/1109f61.jpg http://i62.tinypic.com/1109f61.jpg __
9748	2014-02-14 14:42:44	ehydra	Re: air core toroids
Hm. Makes sense. Thank you! BUT then look at the x-axis: Such formatting makes it very difficult to auto-correct common misinterpretations. - Henry Lasse Moell schrieb: > :p > The always present problem with , and . > > Looking at the diagram you notice frequency is 0.0000 to 60.0000 > So it seems the Q is 0 to 200 in the diagram > > /Lasse SM5GLC >> > Here is the measured Q; the red trace is the solid wire and the blue trace >> is the stranded wire; >> > http://i62.tinypic.com/1109f61.jpg http://i62.tinypic.com/1109f61.jpg
9749	2014-02-14 15:39:47	kerrypwr	Re: air core toroids
It's simple to get Q of 200,000; just cool the device to almost-zero Kelvins. :) The tube is PVC; it is in accordance with AS/NZS1477 which covers PVC pressure pipes. I don't know what the standard says about the material composition; I would have to pay over $200 for a pdf and several hundred dollars for a hard-copy! But I suppose that we can say that sections of white PVC pressure pipe will give Q values of the order shown in my tests (allowing for the excessive "dismal points"). I don't know about toroidal forms though; I might turn-up some toroids from the Delrin and Teflon I have here; there is also some polystyrene I think. I'm not sure that there will be much advantage to the toroid shape; more compact perhaps but I think the SRF might be lower than that of a cylindrical coil. Kerry.