12779	2016-05-02 23:25:01	Ashhar Farhan	wire rating for RF
Message	Date	From	Subject
how does one rate the maximum RF current that a wire can carry? Given a particular wire (let's say 36 swg) what is the maximum current that it can carry when wound over a toroid or an air core? is there any standard table that one can pick this data from? - farhan
12780	2016-05-02 23:37:18	Sandeep Lohia	Re: wire rating for RF
I use multistan wire that isolated from each other by varnish or Teflon coat, can be reused from discarded mobile headphone, followed by high gain ECM... -- Please encourage recycling, reuse or repairing of E-waste. ░7░3░ ░d░e░ ░V░U░3░S░X░T░
12781	2016-05-03 01:52:01	Russell Shaw	Re: wire rating for RF

12782	2016-05-03 01:54:34	Russell Shaw	Re: wire rating for RF

12786	2016-05-03 21:33:28	Brooke Clarke	Re: wire rating for RF
Hi Farhan: In general wire is rated based on some problem such as the insulation failing thus allowing a short. This is a thermal issue and so the thermal characteristics of the insulation and surroundings are part of the solution. The "ampacity" of wire: https://en.wikipedia.org/wiki/Ampacity can be found on line in tables. Here are tables for solid magnet wire and corrections for stranded wire: http://www.coonerwire.com/amp-chart/ When RF is part of the consideration Skin Effect comes into play reducing the DC cross section. https://en.wikipedia.org/wiki/Skin_effect So, in order to use the ampacity you would first need to reduce the physical cross section of the wire by using skin effect then look in the tables. The effect of the torodial core will have a small thermal effect, but not much as it will heat up. In some cases heating of the core becomes a problem of it's own. -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html The lesser of evils is still evil. 2a. wire rating for RF Posted by: "Ashhar Farhan" farhanbox@gmail.com ashhar_farhan Date: Mon May 2, 2016 11:25 pm ((PDT)) how does one rate the maximum RF current that a wire can carry? Given a particular wire (let's say 36 swg) what is the maximum current that it can carry when wound over a toroid or an air core? is there any standard table that one can pick this data from? - farhan
12788	2016-05-04 13:12:57	Sandeep Lohia	Re: wire rating for RF
On Tuesday, 3 May 2016, Sandeep Lohia <sandeeplohia12@gmail.com> wrote: > I use multistan wire that isolated from each other by varnish : https://en.m.wikipedia.org/wiki/Litz_wire -- Please encourage recycling, reuse or repairing of E-waste. ░7░3░ ░d░e░ ░V░U░3░S░X░T░
12789	2016-05-04 14:50:46	Nigel Maund	Re: wire rating for RF
The wickipedia info says Litz wire is rarely used above 2 MHz. So I don't think this meets the design objectives. Regards, Nigel VA2NM
12791	2016-05-04 16:04:43	w3lpl2000	Re: wire rating for RF
I'd hate to think what a few feet of Litz wire designed for use at 2 to 3 MHz would cost! 3 MHz is the practical upper frequency limit for Litz wire, at higher frequencies Litz wire has little or no benefit. As frequency increases, its necessary to fabricate Litz wire out of smaller and smaller wire. Litz wire with equivalent DC resistance to 18 AWG magnet wire is fabricated from one thousand one hundred strands (!) of 48 AWG (0.032 mm diameter) insulated wire. 2 -3 MHz Litz wire is certainly not very practical except for the most demanding military and industrial applications where money is no object... 73 Frank W3LPL
12792	2016-05-04 17:56:03	Russell Shaw	Re: wire rating for RF

12793	2016-05-04 22:14:13	Ashhar Farhan	Re: wire rating for RF
thanks all for the most informative discussion. i will do some tests now with an aircore coil using 36 swg to see if it can take that current. - f