Fred- I assumed a mass of 5 grams with 6 square inches to be heated (2- paddles, 1.5 sq in per paddle side, 2 sides per paddle because heat is transferred off both open faces of the paddles). ?Assumed paddle's heat capacity and conductivity equivalent to Polyethylene. Assumed the temp rise required was 25F. ?The power draw would drain a AA LiIon 1.5 volt in about an hour. ?
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On Jan 5, 2025, at 16:41, John K1JD via groups.io <johnk1jd@...> wrote:
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I also have a pair heated gloves, they run off of C cells. When my hands are warm to start, I can tolerate cold fingers pretty well for the duration of a CW activation unless it¡¯s very windy. That said, heated paddle finger pieces would be a neat trick!
73, John?
On Jan 5, 2025, at 5:22?PM, Fred Maas via groups.io <just.one.hill@...> wrote:
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Wow, Tom, your calculations are very telling.? Thank you for taking the time to do it.
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Remember there are two surfaces to be heated.? What your calculations indicate is that much too much current is needed to significantly warm for this to be feasible using borrowed power from these little radios.
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!!!? fred
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Fred, I have several meters of Nichrome 60 and Nichrome 80; 28 and 18 gauge. Can send up, or bring to you.?
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?Did some estimates- looks like you will need 2 watts to warm paddles 25-40F above ambient. That would take about 8 cm of wire at 1.5V at a max discharge of 1.5-2 amps. ?Could refine estimate with more detailed data about the key, ?but the ?estimate shows it might be feasible-experimental verification on a surrogate set of paddles would be mandatory before assembling.?
That much wire could be wound into a 1-5 -2 cm dia circular spiral or 1.5-2cm wide square spiral that would lay on back of paddles held by epoxy or Silicone RTV. ?Would probably want a potentiometer in there to adjust power to wire.?
