[Elecraft] winding torroids

[Tom Hammond]

Dave:

>I notice that even when I pull the wire tight during soldering the core is 
>still slightly loose. And even if the core is not loose, in a mobile 
>environment the wires will continuously wiggle. So, the wires could 
>fatigue over time. I see two types of adhesive used extensively in 
>electronics these days. Electronic grade RTV and hot melt glue. I'm 
>wondering if low temp hot melt might work for securing the toroid cores. I 
>would avoid hard materials such as epoxy as these tend to compress the 
>cores during cold conditions- I have seen the inductance of a ferrite cord 
>decrease by a factor of five when a core potted in epoxy was cooled only 
>50 degrees C. I wonder if the hot melt is also two hard? I anxiously await 
>your comments, pro and con.

Few, if any, of the cores used in Elecraft kits have enough mass to cause 
wire fatigue problems.

When I install a toroidal inductor, I first solder each wire lead. Then I 
grab each lead in pull on it WHILE I re-heat the joint to remove any slack. 
The result is generally a core which is quite snug and which offers little 
movement, and certainly not nearly enough to cause problems.

I'd suggest you shy away from using anything to try to 'secure' the core to 
the PC board.

Happy New Year.

Tom Hammond    N0SS