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[TowerTalk] KLM 10-30-7 LPA on AB-577??

To: "Tower and HF antenna construction topics." <>
Subject: [TowerTalk] KLM 10-30-7 LPA on AB-577??
From: Michael Tope <>
Date: Sat, 04 Jun 2011 09:54:50 -0700
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I recently acquired a military surplus AB-577 48' mast system and I am 
interested in figuring out whether it will safely hold a KLM 10-30-7 LPA 
log periodic antenna. I've read several accounts of folks using the 
AB-577 to support Cushcraft 402CDs, so it would seem that  using an 
AB-577 to support a 10-30-7LPA might be feasible.

Per the specification in the KLM assembly manual the 10-30-7 LPA has 
30ft boom length, weighs 70lbs, and has a wind area of 8.3sqft. The 
402CD by contrast has a 22.3ft boom length, weighs 44lbs, and has a wind 
area of 6.4sqft.

Apart from the ability of the AB-577 to reliably support the 10-30-7 
LPA, I am wondering about the rotator mounting scheme. The AB-577 lends 
itself to installing the rotator in a "mast mounted" configuration and 
most of the AB-577 installations I've scene pictures of show the rotator 
mounted in this sort of configuration. This concerns me a little since 
most rotators are derated significantly when operated in a mast mounted 
configuration compared to  when they are installed inside a tower with a 
top-tube or thrust bearing to take the side load.

I would appreciate feedback from anyone who has some experience or 
knowledge with regard to the aforementioned topics.

73, Mike W4EF...........


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