This messages provides some, but not all, details about the cable
replacement process for a Force-12 LPT-1242.
As the cables are internal to the structure, it's an involved operation.
I had JV K6JHU and Bob K6XX from the Santa Cruz, CA area replace the two
non-winch cables in my Force-12 LPT-1242.
(Steve K7LXC who originally did the installation was unavailable during
the time I needed the work done.)
For documentation, I received a PDF drawing from Mark at the new
Force-12, but it was a broad outline only, and didn't specify routing,
parts, or tolerances. I ended up purchasing 100ft of 1/8" 7x19
galvanized wire rope and matching Nicopress sleeves (zinc-plated
copper). It appeared the original cable was 3/16" but had grown a bit
in some spots, so I mistook it for 1/8". The 1/8" cable fits fine on
the fiber pulleys, though, so we (by we, I mean mostly JV and Bob, while
I watched) used it. We used two crimped Nicopress sleeves for each wire
termination, and bolt cutters ($20) to cut the wire rope cleanly.
The four Delrin bumpers at the top of the top two sections had to be
removed, and their rivets drilled out, in order to disassemble the tower
for cable replacement. For replacement, 1/2" long rivets were too long,
so we used two washers on the exterior of the tower to keep the rivet
shaft from going through the Delrin bumper and scraping against the
aluminum mast. The washers were next to the rivets at Home Depot,
though not in stack at Orchard Supply Hardware.
There are some obstacles to navigate through as well, getting past the
bumpers. I won't describe the internal cable routing.
One of the wire ropes somehow wasn't taut once when we put the tower
back up, and that stopped the tower rise because it became fouled in the
pulley inside the tower. Luckily, it's possible to make it taut again
by removing the Nicopress sleeves (not a fun task) and shortening the
cable from the outside.
The tower itself had about a half-gallon of water collected inside the
base, even though there was a drain hole in the center, and the base was
mounted on washers giving ground clearance. The hole appeared to be
plugged with mud. We drilled four more base holes in the bottom plate.
Leigh/WA5ZNU
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