Hi Ed,
At W3PP in addition to a number of fixed towers we had 4 of the ab 577's
and two of the 621's. For sure the 621 is more sturdy than the 577 rocket
launcher. At W3PP We had A 6 element 10m beam on one, a 4 element 15M on
another and a 3 el 20M beam and a 2 El Quad for the warc bands all at 50
feet. All guyed at 3 levels. We had the extension kit for one of the
577's that was up 70 feet with 440 and 2m packet antennas using vhf link to
AA1K and up to N3RS in Philadelphia as Dallas had an unreliable dial up
modem at the time. That AB 577 with the packet link on it was attached to
a cement base and house bracketed to the operating building. He did have a
weld break on a 577 base one year. It did not come down but it was leaning
and was re-welded. Lots of different antennas Were on those 577's over the
20 years I went up there. No problems what so ever with any of the 621's
I have a 621 mounted at the end of my house with a C4E mounted on it here
in Virginia. I didn't bother
To install the 40m dipole kit on the c4 since I have an XM-240 on another
tower. The C4e just has the 7 standard element on it right now.
I keep it cranked down to just Above the roof line at 30 feet. I have it
mounted to a cement base (4 bolts) and use permanent anchors (not the
anchors that come in the kit that you pound in the ground) and its mounted
to the house at the end using a home brew house bracket. (we did re-enforce
the inside wall which takes up more room than I would have liked in my
closet but its been rock solid in the 10 years its been in service here. Its
been thru 5 or 6 hurricanes. Easily removed for use in field day. When the
leaves are on the trees, at 30 feet its almost invisible from across the
street when you look at the house from 3 directions. Very easy to work on
the antenna from the roof. Initially, I only put it up and keep up for
contest season Nov 1 - March 15 or when ever the ARRL CW test is. The first
couple of years when I put it up, I got some grief from one neighbor so I
loosened the elements, from the clamps and slid them out and put them in the
garage.I left the elements assembled. Then I left the boom on the tower
rotated it to where it was not over the roof of the house and cranked it
down below roof level. To put it back up for SS, CQWW 10M or ARRL tests it
only Only took about 30 minutes to have the xyl hand me the elements,
slide them back on to the boom, tighten them down and crank it back up.
That neighbor moved a few years ago. I have left the c4 on the 621 rocket
launcher full time. At W3PP he used a 3 wire guy system for his 577's and
the 621's. At this Qth since I have the house bracket, I still use the
standard 4 wire guy system but guy it only at the top. No issues of any
kind here but......being only about 6 miles off the water, I crank the C4
down to roof peak level when a hurricane is coming up the coast. I actually
have one extra 621 tube but never extended it up to 60 feet. I still use the
black plastic covered guy wires and tensioners That came with it For guying.
I would have to look it up but I think the C4 is probably in the 35lb range.
I turn it with a HAM IV. If all I was going to do was go up 10 feet above
the roof line, and, if you can house bracket your 621 to the END of the
house I would just go with the cement base, a house bracket and a second
bracket At the peak of the roof that would go around the 621 tube to keep it
against the peak of the house and Not guy it at all. When my 621 is nested
at 30 feet the guys are attached but not in play. At 50 feet they are in
play. The guy wires which you would not have with the ma 40 are a minor
annoyance. My system does have 2 guys in the ground in the front yard and
two in the back yard. Being black wire, its almost Invisibile even when you
know its there. I clotheslined myself once and The xyl has clotheslined
herself twice while cutting the front grass even though we both knew the guy
wire was there. I now have to cut the grass in that part of the yard
myself. It sounds like you would be putting your 621 only to 30 feet. Do
not even think about cranking either the ab 577 or 621 masts up or down if
there is more than a 5 mph wind. As I mentioned I have loaned out the whole
system for field day or during the years the SS competition With NCCC was
really strong I loaned it out to other PVRC' guys who did not have a station
of their own. Another year we moved the whole system to N4BAA about 5 miles
from here for the WPX CW contest. We used the temporary anchors for the
portable setups. I am surprised that more hams who live in townhomes, or
who have small lots don't put these up. In my opinion the guy who designed
the 577/621 masts was an absolute genius. Rumor has it that NCCC has their
eyes on the SS gavel again. IF they do, PVRC should loan out some of the
field day AB-577's to operators who agree to get on for SS the air. A
tribander at 50 feet, With a 40 and 80m dipole below should easily be good
for 50K points
Good luck with which ever system you decide to go with.
73
Chet N4FX
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Ed G
Sent: Thursday, August 15, 2013 5:30 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Opinions on AB-621 Installation
Hi Folks,
I am helping design an antenna installation for a semi-restricted
community (they allow antennas that extend no more than 10 ft above the
roofline). I believe something like the US Tower MA-40 small crankup mast
with a small yagi would be allowed. But instead of the MA-40 mast, I'm
wondering if I could use an AB-621 or an AB-577, with a concrete base
similar to what I'd use for the MA-40, and a house bracket (again - similar
to what I'd typically use on the MA-40). The antenna would be something
like a KT34M2, which is 40 pounds with a 4.5 sq ft windload. The mast would
be extended about 40 feet, and a house bracket designed to fix the mast to
the house at about the 20 ft level.
Has anyone tried this application for the 621 or the 577? With the
proper size base and house bracket, and small yagi, I am not proposing any
guy wires. Thoughts?
--Ed, N3CW--
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