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Re: [TowerTalk] rope strength - Knot Expert

Subject: Re: [TowerTalk] rope strength - Knot Expert
From: Gedas <>
Date: Tue, 10 Dec 2019 11:29:28 -0500
List-post: <>
Correct. What I ended up using was not a knot and why I called it a "junction" hi-hi. At this point I have learned how to tie a bowline but I doubt I could make one around myself one-handed.

So here is another update of the tower saga. Long-winded warning so do not read if in a hurry.

After repairing the 6m reflector that got blown off the yagi by lightning and ripping out the RG-142/LMR-400 feedline to the rotatable shorty-40 dipole (after finding numerous holes blown through the coax braids to get to the tower) I made a quick SWR measurement of the 40m dipole while only 6' off the ground.

Using my AIM the SWR curve seemed acceptable with a dip at 7.025 and 1.25:1 SWR, which considering the height above ground looked ok to me. I figured once at 71' the dip would raise back it's normal ~7.200 MHz.

That never happened. Once in the air the SWR became highly intermittent with a dip someplace around 8 MHz. Totally pissed off, my XYL & I lowered the tower again so I could examine the dipole feed etc. Everything looked ok so I grabbed my digital LC meter and measured the inductance of both of the loading coils. One read very close to the 11 uH I seem to remember to be the right value, the other was reading all over the place bouncing around like a ping-pong ball. So at that point I knew it was time to loosen all the hose-clamps, drill out the pop-rivets, and bring in the coil sections.

I had repaired these cushcraft coils a decade earlier after the connections from the inductors to the aluminum tubing failed by loose sheet metal screws ( a common CC issue). I cleaned up the solid copper wire coil ends, re-formed the end loops and used a slightly larger SS sheet metal screw to securely fasten the inductor to the tubing. I then put a 2" length of adhesive lined heat-shrink tubing over each end and called it done. That fix worked great right up until the lightning hit last year.

So yesterday when I took my heat-shrink tubing off and exposed the #10 solid copper wire/SS sheet metal screw/aluminum tubing interface I was a bit shocked at the extreme galvanic action that had taken place to all the exposed copper wire ends. They were solid black and very THICK ! I had to use a #2 X-acto blade and scrape each end for about 15 minutes before I got down to shiny copper again. Once cleaned up I applied some "Noalox" compound to both junctions, re-torqued the SS screws and heat shrunk new tubing over each end.

Currently way to windy to attempt to raise the tower so the final test results are still unknown but my fingers are crossed. If you like here are a couple images showing the extreme corrosion that occurred and why, I suspect, the readings were all over the place.

Gedas, W8BYA

Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

On 12/10/2019 8:51 AM, Charles Gallo wrote:
The ABOK is a great reference, but not the easiest to follow

What I believe he did wasn’t technically a knot ( I showed him a drawing)
Make a bight in your line, and pass the bight through a ring, and the spread 
the two legs of the bight, and pass over the ring. Effectively the line makes a 
wrap around the ring, but the line never crosses itself. Fairly normal way of 
putting clips on a flag halyard

73 de KG2V

On Dec 10, 2019, at 6:12 AM, wrote:

The Ashley Book of Knots is a great reference, and there are online
references as well.

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