Pete Smith wrote:
> This year at Dayton, there was a vendor (www.mactenna.net)
> demonstrating something called the SB20-10 Simple Beam. The basic
> principle was described in a QST article in September 2008, applied
I have had a 40/80/160 meter vertical up for about 10 years
switched with vacuum relays that is essentially the same as their
patent. In the May 2009 QST, p 66, I show how to modify open frame
relays to handle high voltage in this application. I wouldn't
be surprised to find out my vertical was a reinvention of a previous
design somewhere, and in any event, it is obvious IMHO. You should be
able to find postings about it in TT or Topband reflector archives from
many years ago. You can patent anything; what else is new?
On my vertical, I still have to have some way to tune across
the 80 and 160 meter bands. The relays only get me into the ballpark.
This is why relays will never replace SteppIRs.
The Mactenna ad shows fairly low SWR across the whole 10 meter band.
Conventional 3 element monobanders do not have this kind of bandwidth,
so the only conclusion I can come to is that there is a lot of loss
in the system somewhere. Also, they do not show gain and F/B at more
than 1 frequency per band. It's not like they have relays to select
various portions of the 10 meter band. You could have additional
relays at the centers of the elements that would switch in small
reactances to tweak the frequencies, but the Mactenna apparently
doesn't have these.
BTW, the Mactenna doesn't do the 2 second 180 degree flip, which
SteppIR owners realize is a huge advantage.
Disclaimer: I'm biased as an owner of a MonstIR and 2 SteppIR's :-)
Rick N6RK
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