While we are waiting for the much desired replies, can people leave out
the "why do you want a log" comments?!
There are as many reasons why people want a log as why they choose a
tri-band over a mono-band antenna. This doesn't make the log any better
or worse of a decision than any other antenna. If someone asked for
comments on best forward gain, then we would discuss that. In THIS
case, the sender is asking SPECIFICALLY about "LP beams". Please stay on
topic and to the "log bashers", take a break on this one. Thank! ;-)
Now to offer some commentary to the question at hand...
The rule of thumb for logs is the more elements, the better the
performance! An excellent article to read on logs (besides all of
Cebik's work) is from September 2002 QST titled, "Practical High
Performance HF Log Periodic Antennas" by Bill Jones, K8CU. ARRL members
can find it here...
http://www.arrl.org/members-only/tis/info/pdf/0209031.pdf You can also
read it on the author's website...
http://www.realhamradio.com/Log_Periodic.htm (everyone else can contact
me for a copy).
I spoke with Mike Stahl at M2 Antennas about his logs. His logs include
KLM's and M2's as he designed both of them! The M2 version added an
extra element (8 instead of KLM's 7) but Mike shared with me that he
could get more performance out of a 10-element with a little longer boom
(he should, remember the rule of thumb). More elements means more
weight, windload, etc. Mike also stated, "...a log at 70' with a solid
kilowatt will not come in second very often..." Take that for what it's
worth.
Paul, NO8D, from DX Engineering, shared years ago with me, that the
original DX Engineering out of Oregon (before he bought the company)
made a 13 element log that didn't perform very well. He fixed it and
installed a bunch of them...
http://www.arraysolutions.com/Users/no8d.htm ...and...
http://www.xxtowers.com/customers/NO8D_photos.php Rumor has it that the
current DX Engineering may sell logs someday!
When Tom owned Force-12 he refused to make and sell logs...but later
gave in and offered them to the military. I have no experience with the
Force-12 log but if it performs like the rest of their antennas, should
be a winner.
I have an original KLM and Cushcraft logs. I used logs in the military
for MARS use. I like them! No, its not a mono-band antenna, but if I
wanted a mono-band, I'd buy a mono-band!
I'm sorry if I can't give you practical LOG experience, but I hope my
links will help you and a couple of phone calls should have you loving
logs too!
Dino - KX6D
-------- Original Message --------
Subject: [TowerTalk] Log Periodic Beam Performance
From: "Wilson Lamb" <infomet@embarqmail.com>
Date: Sun, December 13, 2009 12:34 pm
To: <towertalk@contesting.com>
I'd appreciate hearing of experience with LP beams, especially
performance
vs number of elements. The little T6 spec's are remarkably similar to
the
T10, but some experienced people are pretty adamant that six elements
don't
do a good job.
Anything will be a lot better than the little low endfed I use now, but
I'd
like to have some real idea of what to expect.
The LP is great for getting me WARC coverage and avoiding traps!
Thanks,
Wilson
W4BOH
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