----- Original Message ----- From: "Phil Karn" karn@ka9q.net To: "Tim Cunningham" n8deu@att.net Cc: "'AMSAT BB'" amsat-bb@amsat.org Sent: Saturday, February 25, 2012 1:26 AM Subject: [amsat-bb] Re: Motor for Yaesu G5500 Azimuth Rotator?
On 2/23/12 2:51 PM, Tim Cunningham wrote:
I have rewound a few of these motor coils and a #24 to #26 gauge enamel wire should work. A #22 gauge enamel wire would be too large and you would not be able to wind the same number of turns.
It is the breakdown of the enamel due to wire heating that makes them fail by creating a short circuit in the windings.
I don't remember the wire size I used (it's been over 20 years) but you're right about the short circuit. Just one shorted turn will form the shorted secondary of a transformer, and the I^2R losses in that turn will create quite a bit of heat that will further damage the insulation on the nearby windings until the whole thing is toast.
Hi Phil, KA9Q
To prevent short circuits between turns of the windwing is suffice to use # 24 fiber glass copper insulated wire for class H insulation motors or transformers wich windstand constantly very high temperature around 180° C, Celsius i.e. 356 ° Fahrenheit.
I have used it with success in critical applications to rewind DC and AC motors working near steel melting fornaces for a Company in Italy 50% with the USS Steel in Pittsburgh Pennsylvania.
73" de
i8CVS Domenico