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Re: [TowerTalk] AB-577

To:, "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] AB-577
From: Neil & Heather <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Tue, 20 Apr 2010 15:13:14 -0400
List-post: <">>
Good eye's Dick,
I didn't notice it was missing the top mast assembly.
(agree, a must have).
I also have a AB-577, personally delivered to me in Keene
NH from Ben himself ( a couple of years ago.
I doubt i will ever part with it, its definitely an engineering marvel.
I've seen many ask about availability,and I know they're getting scarce,
hence why I posted the link...I know some have been looking for the
AB-577 for Field Day.


On 4/20/2010 1:42 AM, Dick Green WC1M wrote:
> I have three AB-577s, one with a homemade (to spec) extension kit, so I'm
> quite familiar with them.
> There are a few odd things about the one listed on ebay, so I would urge
> caution for anyone interested in buying it.
> First and most important, you should know that the stock mast goes to 48
> feet, not 60'. The kit offered for sale appears to be an incomplete
> collection of parts from two or more AB-577s that have been put together to
> get the extra height. The stock guy anchors are installed 30 feet out, which
> is the default distance measured by the supplied measuring rope. It's
> already pretty close for a 48-footer (60% of height), and in my opinion way
> too close for a 60-footer. I would push the guys out to at least 40', if not
> 50' (the rope can also measure that distance because it's used for the
> extension kit -- see below.) Even then, I doubt the mast would meet its
> original engineering specs at 60 feet with only three guy sets. The clamps
> used to mate the tubes are not very rugged and can't take a lot of lateral
> force. The greater the distance between the guys, the more lateral force
> will be on the clamps. Also, it may be very difficult, or even hazardous, to
> erect the unit with that much distance between the guys. Before final
> tension is applied, the mast behaves much like a wet noodle. The greater the
> vertical distance between the guys, the more exaggerated this effect will
> be. This tends to get worse the larger the antenna.
> It appears that the original installation manual does not come with this
> unit. I would urge anyone buying it to get a copy of the manual and read it
> carefully (there are probably some scans online.) The installation procedure
> should be followed to the letter to ensure safety of all personnel and
> equipment.
> Additional information:
> The stock AB-577 comes with eight 5-foot tubes, which is the maximum number
> the portable carrier will hold. The five tubes with the 8-foot launcher
> gives you 48 feet. It also comes with two different guy rings, one for the
> top guys and one for the middle guys, plus an antenna adapter. The three
> guys anchors are installed 30 feet from the base.
> The extension kit comes in its own plastic carrying case (that's the one
> piece I don't have.) The kit adds five more tubes, for a total height of
> 73'. Also included are an additional guy ring, two more guy sets and three
> more screw-in guy anchors. The stock bottom and middle guys remain at their
> stock positions and still run to the stock anchors 30' out. The longer of
> the two new guy sets replaces the stock top guy set. The other guy set is
> installed halfway between the top and stock middle guy, using the additional
> guy ring. The two new guy sets attach to the extension anchors, which are
> installed 50 feet out. So you end up with four sets of guys, the lower two
> sets anchored at 30 feet out and the upper two sets anchored at 50 feet out.
> The non-standard height of the unit for sale on ebay, and the fact that it
> comes with two launchers, two carriers and three middle guy rings, makes me
> suspect that it's a combination of at least two AB-577 sets. It appears to
> be missing two standard parts: the top guy ring and the antenna adapter.
> Without those parts, one of the middle guy rings would have to be used for
> the top guys, and that would require putting an unguyed tube above the top
> guy ring. It's not safe to put an antenna at the top of that (again, the
> ring clamp can't take the lateral force), so the antenna would have to be
> placed at the bottom of the top tube with some sort of homemade adapter (the
> stock antenna adapter has a short piece of ~2" mast welded to it that's
> perfect for mounting an antenna bracket or a rotor bottom bracket.) I think
> this might explain the discrepancy between the description, which says it
> comes with 11 tubes, and the parts list which says it comes with 12 tubes.
> The top tube, for all intents, gives you no additional height.
> The unit is also lacking the canvas roll, used for storing and carrying the
> anchor stakes, sledge hammer and claw bar (the latter two also appear to be
> missing, but that's not unusual). It's also missing the canvas bag used for
> carrying the guys sets, rings, clamps, etc. I don't see the "winch spanner"
> listed, either. This is a special tool that can be used to rotate the mast
> after it's been erected (the guy rings slip to allow this.)
> The original AB-577 guy sets came with 1/8" stainless steel guys.
> Refurbished models usually have plastic-coated galvanized aircraft cable.
> Stainless guys work better with the "snubbers" used for tensioning the guys,
> but the plastic-coated guys do work (my two 48-footers have plastic guys but
> someday I'll replace them with stainless.)
> As for the price, I'd certainly pay $650 for a complete 48' kit, but it
> really depends on the condition of the parts, especially the clamps, which
> tend to wear out with repeated use, and the guy sets. The collection of
> parts offered on ebay is probably worth $650-$800 if the parts are in decent
> condition --  the extra launcher, tubes and middle guy rings are worth money
> for sure. But I'd look into sourcing as many of the missing parts as
> possible, specifically the top guy ring and antenna adapter. If the plan is
> to take it over 48', I would also get three additional screw-in anchors and
> an additional long guy set (or make one using the snubbers from a shorter
> guy set.) Ontario Surplus ( has most
> of the missing parts in stock. They also have a few complete 48' kits
> available, so you can compare the price.
> 73, Dick WC1M

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