Date: Tue, 28 Nov 2017 17:14:40 -0800
From: "AA6DX - Mark" <cqdx@suddenlink.net>
To: "TT" <towertalk@contesting.com>
Subject: Re: [TowerTalk] 2-el 15/20 meter duobander
<In the wayback, (70S), I contested/dxed using a DB-54 Wilson on a 40'
<boom -- was interlaced 20/15 -- and, the 4 15M elements were inside the
<20M. If memory serves me, this design was in the QSTreet magazine..n'est-ce
<pas? Had it on a W-67 tower, which bit the dust, after I added a 6el Wilson
<for 10M on the tippy-top -- an educating experience! B U T -- in the
<meantime, worky-worky!
<73 -- Merry Christmas -- Mark AA6DX
## we had several of the interlaced wilson yagis here in town back in the 70s.
None of em worked worth a damn. The higher freq always suffered badly.
## I had a wilson 5 el 15m yagi, on a 26 ft boom, it too was a dud. My
conclusion
was Wilson had no clue as to what they were actually doing. Nobody had a clue
how to handle
swedged eles back then. Another local buddy also had the wilson 5 el 15m, and
4 el on 10m
yagi. You think my wilson 5 el 15m monobander was bad, adding 4 els to it
for 10m was even worse.
15m was severely de-graded, and 10m portion was a total write off. The
wilsons would sorta work, provided
you installed them up high , like 70-100 ft, and stuffed several kw into them.
## My last version of YO was called YO-7.05 YO would not do a 2 el yagi,
only 3 els and more.
The only way around that was to make the boom super extra long, like say 150
ft or more... to put the
director way out at the end of the boom, so the REF and DE did not ..see the
DIR.
## YO would not design any interlaced yagi, only monobanders. YO would
also not allow you to design
any OWA yagi either. YO software would not allow any 2 els to get closer than
.09 wavelengths, so that killed
any notions of any OWA design right there. YO had a limit on how long..or
short each ele could be..in any
monobander. Trying to tweak a gamma or oemga match on a DE that was way out
on the boom was a trick in itself.
Ditto with any version of a HB hairpin.
## another contester buddy had the 3 el 20m telrex..on a 26 ft boom. The
boom was way too long for just
3 els. Els are fixed on any telrex, so the best I could do was to tweak the
tip lengths, which made a huge
impact for his application.
## I forget how I handled swedged eles in YO, it was a real bitch. I believe
I had to take each swedge and segment
it down into smaller segments, where each swedge was. Im talking about where
the ele reduces from say
1.25 inch OD...down to 1.0 inch. With each ele having loads of swedges, the
design is easily messed up.
## These days, I use tubing that slides into the next, or if having to jump
diameters, use inserts that still allow for tubing
to slide easily into the next section... no swedges.
## some of the..yagi designs back in the 70s were totally off the wall.
Then along comes telrex with its 6 equally
spaced els for their 6 el on a 46 ft boom. Ditto with their 8 els on 15m,
also on a 46 ft boom..... and ditto with their
10 el on 10m, also on a 46 ft boom. Again, the best I could do was to tweak
the tips, since eles were fixed.
## back then, loads of triband, trapped yagis, with the usual issues of lousy,
int trap connections, melted traps, blown
baluns, mosely baluns, etc. One local fellow had the big telrex
tribander..that used traps that consisted of a coil,
plus a doorknob cap in parallel with the coil, then the entire mess covered in
heat shrink. Caps were typ replaced in
the DE every 2 years.
## then a bunch of us decided to stack 20-15-10m monoband yagis on the same
mast, in various xmas tree configs.
Typ the interaction between yagis resulted in a net loss of gain and fb...
negating any benefits from using monobanders
in the 1st place. Then several locally used the infamous hygain 402BA. The
small, short spacers they used for the LL,
some were at HV points, and would either short out, carbon arc, or self
destruct..and were replaced on a regular basis.
## I never owned any quads, but helped a lot of folks install them , or repair
them..usually after a 70 mph wind, and or
ice or snow loading. After a half dozen repair jobs, I decided I would
never entertain the thought of owning a quad, or
delta loop etc. If you want a real laugh, stuff some of these old yagi
designs from the 60s and 70s into NEC-4. Then
you will see why a lot of em did not work as advertised.
## The old days were fun, but a real pita. The only thing that worked
correctly back then was my small prop pitch,
until it got water in it..and my 3 hb amps. Ok, end of rant.
Later... Jim VE7RF
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|