In a message dated 10/8/2006 10:52:43 A.M. Central Daylight Time,
w9ac@arrl.net writes:
> OK, here's a question: any recommendations for a coil former material
> that can withstand a bit of heat? The 80/160m tank coil in my amp gets
> quite warm during RTTY contesting - not hot enough to indicate a design
> problem, but even a moderate increase in temperature makes the
> fibreglass tubing former smell quite unpleasant.
Ian:
How about no form at all? Can you increase the wire or tubing size and only
use a form for winding purposes only -- then remove the form. With large
enough wire or tubing, a form should not be required unless you have many
turns.
In the alternative, I've seen many ceramic coil forms on the surplus market
from EF Johnson, Millen, and National.
Paul, W9AC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
Or, an in between approach if you have a little extra space:
A Lexan, fiberglas or similar flat insulator can be cut and drilled with
evenly spaced holes to allow the coil to be "screwed" through the holes thus
providing two support points for each coil turn. The ends of the coil can also
be secured to the insulator or left hanging in air as needed. Drilling
slightly oversized holes makes the "screwing" job a lot easier.
The insulator can then be mounted with skinny standoffs, metal or insulated,
to the chassis or side wall as needed.
Even 1/8" thick material seems sturdy enough to do the job.
73,
Gerald K5GW
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|