On 1/26/21 3:04 PM, n2msqrp wrote:
Dave,
Have you tried teflon covered silver plated wire?
Mike N2MS
The silver doesn't help much for RF conductivity, but it is a LOT easier to solder to.
I'm kind of surprised that magnet wire broke down. Most magnet wire is good for a kilovolt or so, because motors and transformers get hi-pot tested at 2-5kV.
Decent insulated magnet wire
Catalog here:
AWG 12 copper bare is 0.0808 (nom)
single build is 0.0825 (i.e. the insulation is 8.5 mils (0.2 mm) thick
heavy build is 0.0842 is twice as thick. (0.4mm)
most plastics have breakdown strength of 20 kV/mm or more, especially for thin layers.
PTFE (Teflon) and Polyimide (Kapton) are a lot better (100 kV/mm)
Polyester (Mylar) is in between (50kV/mm)
Note that thinner layers have a higher breakdown voltage per mm (that is, you might find that a layer that's 0.1 mm and 1mm have almost the same breakdown voltage)
Formvar is about 11kV as typically applied to wire.
On 01/26/2021 3:30 PM David Eckhardt <davearea51a@...> wrote:
Those wound with the #12 enameled solid conductor do not take power with
my ant/feedline impedances resulting in discharges between bifilar pairs
(not between individual bifilar windings).? Also, the green wire of
unknown insulation does not take power.? So, those CMCs wound with solid
conductor are coming apart and being rewound in some fashion or another
with the DavisRF "antenna" wire which seems to take power to at least 1.2
kW.? Your mileage may vary with different impedances presented to the
chokes.
Those frequencies on which I tried the CMCs at power are:
3.8 MHz ? ? 24 - j56
7.15 MHz ? 493 - j740
Impedances noted are measured at the shack end of the parallel wire
feedline.
Dave
