[TowerTalk] HyGain 155CA dampening rope

[Bob Shohet, KQ2M]

There are two reasons.  

1) Many of the screw clamps do NOT tighten enough to keep the element pieces from slipping.  I used to test the clamps but tightening as much as possible (without stripping the clamp) and then trying to pull out the thinnest element piece – I succeeded ~ 50% of the time.  meaning that over time and the normal expansion/shrinking cycle due to the seasonal temperature changes (coefficient of thermal expansion) would almost certainly cause the element tip to extend and ultimately fall out aided and abetted by any wind.

2)  The loose fit would allow the element tip to vibrate, which after a period of time, would cause metal fatigue which could easily cause the element tip to crack and/or break off.  And, once the element tip begins to crack, moisture can get in and then freeze which would expand any crack or possibly fracture the element tip.

These are the two most common types of element tip failures associated with the Hygain antennas and most other types of antennas.

Using my two Stainless Steel hoseclamp method and flattening the hoseclamp ends and taping over them, I have never had a failure of this type in 18 years on 11 different Hygain Yagis (105CA, 155CA, 205CA).  Which, given the prevalence of ice-storms (averaging 7 per year!), Nor’easters, violent T-storms and Hurricanes at my qth, is as good any :”real-world” antenna “test-range”.    ;-)

BTW, not all stainless steel hoseclamps will tighten all the way either – I know this from the same test that I performed on the Hygain Screw clamps.  With the hoseclamps, if they don’t tighten all the way and keep the element completely unmovable, I replace the offending hoseclamp with one that WILL keep the element tip completely tight.

73

Bob KQ2M

From: john at kk9a.com 
Sent: Thursday, June 22, 2017 8:43 AM
To: towertalk at contesting.com 
Subject: Re: [TowerTalk] HyGain 155CA dampening rope

Why would the screw clamp have any effect on the elements braking?  The
parts website seems to indicate that HyGain uses 0.028" wall thickness on
their 20m element tips.
http://www.hy-gain.com/Product.php?productid=174939.

John KK9A



To: "Bill Parry" <bparry at rgv.rr.com>, <towertalk at contesting.com>
Subject: Re: [TowerTalk] HyGain 155CA dampening rope
From: "Bob Shohet, KQ2M" <kq2m at kq2m.com>
Date: Thu, 22 Jun 2017 07:47:51 -0400


Bill,

Did you use the stock Hygain screw clamps at the end of the telescoping
elements or did you use stainless steel hoseclamps like I do?

73

Bob  KQ2M

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