RadioBanter - View Single Post

March 30th 06, 02:42 AM posted to rec.radio.amateur.antenna

wrote:
John Popelish wrote:

My point was that there are cheap long form factor toroids available
now, that weren't available when W2DU designed and described his BalUn.

My point is dollar for dollar multiple turns always wind up being a
better investment. That's because impedance approximately follows the
square of the passes through the core.

At low frequency, I understand how this is a good approach (though
this discussion was about the W2DU style choke balun). But at higher
frequencies, I am concerned that the turn to turn capacitance might
provide a low impedance path that parallels the choke. A string of
beads does not have this problem.

....
But it spreads the heat out, and doesn't require you to kink the coax,
which makes it last longer in the weather.

I've never once had cable fail from being wound on cores. I can't
imagine why someone would need to kink the cable.

I always try to not bend any cable to a smaller radius than the
manufacturer recommends, and I am not familiar with this
recommendation for common coax types used by amateurs. I would have
to look that up before wrapping a core.

The only part of the cable that significantly increases CM impedance is
the part inside the core window. Why care how tightly the cable is
pulled against the core outside??

The weight of the cable will tighten the turns on the core.