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#1
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Toroids coating
Hi,
does anybody know if coating on Amidon toroidal cores has any dielectric properties, such as a particular breakdown voltage rating, or it is not meant for electrical insulation. Thks |
#2
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Toroids coating
Why not email or visit amidon.com ??
tori Ivan Makarov wrote: Hi, does anybody know if coating on Amidon toroidal cores has any dielectric properties, such as a particular breakdown voltage rating, or it is not meant for electrical insulation. Thks |
#3
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Toroids coating
From: Tori Thurs, Dec 1 2005 9:23 pm
Why not email or visit amidon.com ?? www.amidoncorp.com to reach the correct site. |
#4
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Toroids coating
Amidon dust-iron cores are not uniformly coated.
It is just a colour-coding paint, sprayed on. Otherwise the paint may just as well not be there. |
#5
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Toroids coating
From: "Ivan Makarov" on Thurs, Dec 1 2005 11:47 pm
Hi, does anybody know if coating on Amidon toroidal cores has any dielectric properties, such as a particular breakdown voltage rating, or it is not meant for electrical insulation. Since Bill Amidon sold his business to another company, the "new" Amidon company has been reselling another company's toroidal core forms. The original Amidon company resold Micrometals toroidal forms.* Micrometals still very much in business in Anaheim, CA; website: http://www.micrometals.com Micrometals also makes power-application toroid forms for 60 Hz and those are described as coated with Parylene C with a given insulation rating of 500 V RMS at 60 Hz. By casual observation of some Micrometals powdered iron toroid forms I have on-hand, the coating appears to be the same. Parylene is a relatively inert polymer which is unaffected by typical hydrocarbon solvents found in varnishes and lacquers. I use McCloskey "Gym Seal" varnish (oil based) as an over-coating of finished toroid windings with great success in withstanding humidity and general aging. That is available at most do-it-yourself hardware chain stores. The same could be applied to the "standard" toroid forms if more insulation of the core is desired. The coatings on most toroidal cores is applied mainly to protect the core material from oxidation. One can get uncoated cores on special order but those unused cores should be sealed away from air movement to avoid oxidation. The second reason for a coating is to make winding easier and reduce sharp edges that could stress the wires (true even with special toroid winding machines)...especially if winding by hand. There's not much need to worry about core insulation with powdered iron materials. The powder itself is in a binder which adds some isolation from breakdown in addition to holding it all together. On actual application, check out one of the early Amidon kits available in electronics stores, a 1 KW Balun kit with huge core (to handle the RF power) and rather ordinary coated solid wire. The RMS voltage at 1 KW in a 600 Ohm open-wire feedline application is 775 Volts. Given that real-world antennas can get mismatched, high VSWR situations could have double that voltage fairly easily. I've never heard of any such Amidon baluns that flashed-over in normal use (disregarding lightning strikes). * Micrometals has a minimum quantity requirement on orders, used to be minimum of 100 of any type core...that might have changed. |
#6
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Toroids coating
Nice posting, Len, thank you.
Ivan wrote in message ups.com... From: "Ivan Makarov" on Thurs, Dec 1 2005 11:47 pm Hi, does anybody know if coating on Amidon toroidal cores has any dielectric properties, such as a particular breakdown voltage rating, or it is not meant for electrical insulation. Since Bill Amidon sold his business to another company, the "new" Amidon company has been reselling another company's toroidal core forms. ... |
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