03-01-2021, 02:24 PM
If you have carefully measured and get #41 then that is what it is. It should be enameled (dark color) and have a single wrap of silk.
The coil was probably wound under some tension and could have stretched from #40
If you cannot find the exact wire consider...
The turns are most important. The wire is universal wound. The combination of universal wind and the silk covering are to lower the capacitance/turn.
Unless you have a Morris winder and the correct cam one cannot wind universal. However, scramble wind will also distribute capacity fairly well.
If the coil is very narrow, "cheeks", of cardboard or bottle plastic can be installed on the form with a tiny bead of epoxy after removing all the wax... Then scramble wind in the slot... Must wind in the same direction and connect the "start" to the same connection.
You can use #40 but be prepared with a slightly larger diameter. Modern wire will be a light amber color and have "solderable" insulation so there is no need to scrape the wire to clean off the insulation. Drip bees wax over the coil to secure the windings and warm the coil with a heat gun to flow the wax... Be careful not to melt plastic cheeks if that is what was used...
It is the turns that are most critical add several extra if need be...
If you cannot get accurate turns and you know the resistance of the wire by size then the length and weight of the bare wire can be found..
That creates another problem: Weighing the wire adding for insulation accurately or measuring length. Both difficult. I use a length method as I have a rotary counter with a wheel with 12" of circumference. wire is looped over the wheel and spooled to length.
You can also measure inductance on the fly or resistance or inductance. But the wire must be sealed if it is scrapped to make a connection. The difference even in tenths of an ohm can be many turns...
If there are too few or too many turns the coil will not resonate in the range of the tuning capacitor. Too many turns are better as turns can be removed easily...
GL... chas
The coil was probably wound under some tension and could have stretched from #40
If you cannot find the exact wire consider...
The turns are most important. The wire is universal wound. The combination of universal wind and the silk covering are to lower the capacitance/turn.
Unless you have a Morris winder and the correct cam one cannot wind universal. However, scramble wind will also distribute capacity fairly well.
If the coil is very narrow, "cheeks", of cardboard or bottle plastic can be installed on the form with a tiny bead of epoxy after removing all the wax... Then scramble wind in the slot... Must wind in the same direction and connect the "start" to the same connection.
You can use #40 but be prepared with a slightly larger diameter. Modern wire will be a light amber color and have "solderable" insulation so there is no need to scrape the wire to clean off the insulation. Drip bees wax over the coil to secure the windings and warm the coil with a heat gun to flow the wax... Be careful not to melt plastic cheeks if that is what was used...
It is the turns that are most critical add several extra if need be...
If you cannot get accurate turns and you know the resistance of the wire by size then the length and weight of the bare wire can be found..
That creates another problem: Weighing the wire adding for insulation accurately or measuring length. Both difficult. I use a length method as I have a rotary counter with a wheel with 12" of circumference. wire is looped over the wheel and spooled to length.
You can also measure inductance on the fly or resistance or inductance. But the wire must be sealed if it is scrapped to make a connection. The difference even in tenths of an ohm can be many turns...
If there are too few or too many turns the coil will not resonate in the range of the tuning capacitor. Too many turns are better as turns can be removed easily...
GL... chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
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