I'm certainly no expert but I've built loops, half wave slopers, switchable
quarter wave slopers, beams for 6 meters and 15 meters, verticals, shunt fed
towers, 160 meters short verticals, and run various beams on 40 meters and
up, and done a lot of reading over the years and talked to guys phasing
verticals and inverted vees and loops on 160 and 80 meters as well as 40
meters.  I bought, for 100 dollars, a 4 element 20 meter beam once from a
friend.  I only had a 38 foot tower bolted to the house at 14 feet and one
set of guys at 35 feet.  It never even moved at 38 feet.  I had no readout
on an old Ham M rotator but the frontal lobe was so sharp on that 4 element
yagi, I could literally peak the signal by swinging the beam by ear.  The
build up, and drop off, of the lobes from the corners of the beam were
amazing.  Hygain rated it at 9.9 DB forward gain.  They had a 24 foot boom,
just like the TH6, as I recall, and you could buy a kit which made the boom
8 feet longer, adding an additional element, and get, they claimed, 11 DB
forward gain.  Back in the late seventies and early eighties, the HF bands
were amazing.  Not as good as the late sixties, but pretty close in my
opinion.  I sold my 4 element 20, to my friend with the 4 element 40 I
mentioned in an earlier post, and bought a used TH6DXX from a friend.  It
needed cleaning up so I bought a whole new stainless steel kit of nuts and
bolts and washers and screws clamps, along with new plastic element tip
covers, all in one package from Hygain, cleaned up the elements, and a
friend I knew from mostly 6 meter side band came over, his wife was a ham,
too, and in a cold windy November day, he and a friend, along with his wife
and I pulling on the ropes, put up that TH6.  Hygain claimed it was a little
over 8 DB forward gain and it functioned, using its 6 elements, as 3 wide
spaced elements on 20, 3 elements on 15, and 4 active elements on 10 meters.
I still used the old Ham M rotator with no knob to point and no tone and no
speech.  It was very difficult to peak by ear a signal on that TH6 compared
to the 2o4B A due to the much wider frontal lobe.  I managed but I didn't
like it.  The difference between the two antennas was less than 2 DB,
supposedly, again according to Hygain, but on the air, there was no
comparison.  I worked stuff with the 4 element mono bander more than I ever
did on 20 with the 3 active elements of the tribander.  You wouldn't think
that just 2 DB would make that big of a difference but the energy efficiency
envelope of a monobander squirts the signal into a smaller, more narrow,
lobe, than a tribander and it is amazing the difference that can actually be
heard.  Most 2 element 40 meter beams, depending on boom length and element
length run about 6 DB.  My Cushcraft was on a 16 foot boom and supposedly
had 6.1 DB gain.  Telrex, on the other hand, has a 19 foot boom on the same
antenna design , with about the same element lengths, and they claims 6.6 DB
gain.  It doesn't sound like much, but it shows up on air.  Should the
average ham care?  No, that's why I got the TH6.  I wanted 15 and 10 meters
before the sun spot cycle dropped off.  I got one good season and hung out
mostly on 15 meters.  So, it's a trade off no matter how one goes when it
comes to gain.  Can you work that guy, is all that matters I guess, but it
is always fun being first in a huge pile up.

Phil.
K0NX