> I recently built the tube version of the BCS. I used 2" dia tubing up to
> the 40m trap then transitioned to 1.5" tubing upt to the 80m trap. I
> followed the LC type trap guidelines in ON4UN's book. Both 40 and 80
meters
> work well although they resonate a little high, I can easily fix that.
Tom, you really don't want the traps to be exactly resonant at the operating
frequency. When you do that, the loss is at the peak value.
Traps work perfectly fine 5% or more off frequency. All you need do is
adjust the antenna length slightly to compensate.
I have some trap measurements at:
http://www.w8ji.com/traps.htm
> problem I seem to have is on 160. When i first put the antenna up, I
> couldn't get a sharp resonance on 160m. I was expecting 20 to 30 khz or so
> of bandwidth.
Since that antenna is a Marconi Inverted L and nearly full size, I'd
certainly expect a wide bandwidth. Contrary to popular wife's tales wide
bandwidth isn't always bad. It can mean something, but unless you know a
great deal more you certainly cannot judge efficiency from bandwidth. As an
example my widest bandwidth mobile antennas have the highest efficiency, not
the lowest.
73 Tom
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