A couple of things that have nothing to do with each other. First something that just seemed funny - strange to me.
Yes, it's real, and no I don't have one. I don't end up caulking things often enough to justify it. Mark 1 finger works well enough, and I've never gotten splinters.
The hurricane cleanup was largely in a back corner of our property where my
next door and back yard neighbor's trees had dumped on the workshop's
roof. The hazardous one is the back yard neighbors because they have an
enormous tree that dropped a branch on the roof that was hard to get rid of,
not just because it was 5' long and heavy but also because it was still
attached to the rest of that tree. I had to chainsaw a couple of chunks
off it while standing on a ladder before I could drag it off the roof, then
chainsaw that log into smaller pieces to carry to the curb. The roof is
cleared off, though, and there are no indications of roof damage. It
could have been much worse.
Next door neighbor has different trees,
but the one that always causes hassle is her bougainvillea. Pretty
flowers but thorns big enough to kill a rhinoceros. Mrs. Graybeard and I
came in with matching scratches on our right arms from brushing against a
branch. You have to pick up branches very gingerly to drag them to the
curb. The surprise there is that I had four broken off thorns in my
shoes after we finished and they didn't go through the soles of my running
shoes and jab into my feet.
Cutting back the branches in that area
took all day Friday. Saturday I sat down to fix the antenna elements and
ran into a supply issue - as in I don't have any metal I can machine into the
parts I need to fix it. I need to describe the situation and how I
intend to fix it.
The antenna had one of its dipoles snapped off - the before picture is in
Thursday's post. The metal tubing that snapped was 5/8" outside diameter and the
remaining broken-off parts sticking out of the antenna's boom are about 6"
long. Here's the after picture with the broken-off parts
highlighted. This was almost as soon as I cranked over the tower and it
stopped raining. I've since sanded those broken tubes to shiny metal and sawed
off their jagged ends.
Think of a broken pipe plumbing problem. A standard fix for a copper
pipe is to clean up the ends and then silver solder a sleeve over both ends
(quick example). Since every joint in the antenna's elements is two pipes slipped
into each other and attached with a self-tapping screw, I thought I'd machine
a sleeve made of aluminum around 6" long to 5/8" ID. As for the OD, 3/4"
seemed natural but only the ID matters. I figured each of those ends on
the antenna boom and the ends of rest of the broken off elements would get
about 3" of sleeve and I'll use two screws on each side of the break.
It turns out that 5/8" ID aluminum tubing isn't particularly easy to find. Another possibility would be to start with a 3/4" aluminum round bar, drill it on axis and then bore it to 5/8" ID on my lathe. That's throwing out almost all of the bar, but sometimes you gotta do what you gotta do. Unfortunately, I don't have pieces of aluminum that could be turned down to 3/4" and 4 to 6" long. A 12" long bar is on order and will be here tomorrow. It's possible I'll get the elements repaired in the next day or two.
As for mounting the tower and the house bracket, I will go to 1/2" x 3" long
lag bolts for a short term fix just to get the tower up and out of the
way. The "real" long term fix (which hasn't been imagined yet) is going
to be in a month or two; "when it cools off."
Tennadyne? Little one like a T-6?
ReplyDeleteI've had broken elements on a T-8. Seemed that insects built a nest which held moisture that mixed with the insect dung to weaken the aluminum.
Tube sizes are common, and if a Tennadyne Rog was willing to make up new elements if you were not in a hurry. Thinking the new owner of Tennadyne might do the same.
If you have found the missing elements, your splice can be inside or outside of course.
Very glad you avoided serious storm damage.
73
It's a T-6, and fairly old. I think I put it up in the early 2000s, pretty sure it was around 2000, itself. The screws are simple self-tapping sheet metal screws. The broken off halves of the elements are trimmed, sanded and ready to mount.
DeleteYou are absolutely spot-on about bugs. I'm pretty sure they're mud dauber wasps. They seem to prefer to stick their mud on the sides of the house and the roof soffits, but both elements on both sides of the boom were plugged with hardened mud. Because of the way the elements are attached to the boom, to clean out all of them would mean taking every element off the boom because of the through bolt that mounts them to the boom. Maybe a very long rifle cleaning rod would work to crack up the mud and get it out, but it would be tough going.
It would sure be easier to start over and replace the antenna.
Should have mentioned that the self-tappers have given way to stainless machine screws with self-locking stainless nuts for current production of these antennas. At one point Tennadyne offered a retrofit kit for sale, that included the right sized drill bits.
ReplyDeleteOther thing worth mentioning is how much more time the bigger versions of these LPDA take to assemble. I put together a T-12 single handed, which performs excellently. Took three time longer to assemble than the last T-8 I put together.
AC has some ham questions:
ReplyDeletehttps://adaptivecurmudgeon.com/2022/10/03/ham-question-please-help/
Could you or someone else please help him? TIA!
I saw the post title and went to take a look but I know virtually nothing about the things he's asking about. It's that "ham radio is a thousand hobbies with one name" thing.
DeleteWhat Steve said: machine a rod to fit inside the pieces, put together, drill holes through the whole thing, put stainless bolts (I'd use 10-32) completely through and add locknuts.
ReplyDeleteD'oh! Double D'oh! Why didn't I think of that?!?! For sure, I have more than enough 1/2" aluminum to do this fix. I have stainless 10-32 screws, just no locknuts. There's a hardware store up at the corner a mile away.
DeleteI've sprayed a couple things into the elements of the current T-8, but it is too early to tell if it worked. Basically persistent sprays that hopefully the insects continue to avoid.
ReplyDeleteWhen tipped over I jet them out with air and my power washer, from the small end. Again I cannot say if long term durability is improved, but I feel better for the effort!
Presently I have one tower set up for a T-28 stacked above a new T-8. My original T-8 developed crystalline areas of powdered aluminum in the square boom sections after the neighbor's nearby oak tree was solidly smacked by lightning. Whatever jumped to my antenna system damaged the old T-8, ate the rotator with it's Green Heron controller, and toasted the remote switch.
The original T-8 was well abused before the mud daubers and near lightning issues, as the elements were well flexed due to several ice storms.
https://k9zw.wordpress.com/2017/12/10/replacing-an-old-t-8-with-a-new-tennadyne-t-8-at-the-k9zw-home-qth/ has a couple pictures.
My other personal tower has a T-12, which there is also some pictures of.
I quite like LPDA, having run them for several decades. Simple construction, hear and transmit very well at what you point them towards while reasonably ignoring signals from side directions, usually don't require an antenna tuner, handle QRO (higher power) use easily, are very usable at most any frequency within their design specs, and you can band switch quickly at will. On the T-12 I've found using it with an antenna tuner at modest (barefoot) power gets a few extra bands as well.
73
Steve
K9ZW
About spraying the T-8 elements, have you considered using plugs to seal the ends of the elements?
DeleteCaps or some sort of plastic plug with a bit of taper to ensure it goes deep enough into the tube seems like it should work. Seems like a good 3D printer project, although I like the idea of something flexible or compressible.
Rog, the previous longtime owner of Tennadyne, recommended against sealing, as experience showed damaged from moisture close spaces, as well a stuff that happened at the outside where grime (and maybe insects again) built up.
DeleteAs elements do flex a fair bit more than expected in weather, so thinking to try this you would need a flexible sealant at the element joints?
My gut feeling was to not seal the joints. We don't get ice coatings on things, so the most movement we get at joints is the wind blowing the elements. When the wind is right, the T6 sounds like a giant pan flute. The mud dauber wasps aren't very small and I don't think they could get into the ends of the small tubing. I should check into that while it's in an accessible position - run a solid copper wire or something into the end of one.
DeleteIf they can't get into the small (1/8?) openings at the ends, leaves just the boom ends of the elements to protect.
Steve, SiG -- What if one put a drain channel on the bottom of the plug. The plug would keep out the mud daubers but allow air and moisture to flow. I know about the problem with those wasps as we have them here near Bandera, Texas. There is though another issue; there are some small bees that have habits similar to mud daubers but they like smaller holes. I don't know if one can win for losing.
DeleteThe moisture issue would be a reason to not use solid rods to mend the elements back together as malatrop suggested. However, a channel milled in those would allow flow.
Wow - plastic fingers. That's hard to grasp.
ReplyDeleteJW: you can't keep your puns confined to your blog, can you? :-) Good thing. I think.
DeleteCutting the tip of the caulking tube to the proper diameter and angle means a proper caulk with no finger needed. In theory...
No, I really can't help myself.
DeleteWould appreciate any data or experience with the capping/plugging ideas. While the new owner of Tennadyne brings energy to the product, the long time owner Rog, and before that the originator Chuck, brought years of user field reports to the table.
ReplyDeleteAnything I can gather and collate would also be shared with Tennadyne, as why reinvent the wheel?
73
Steve
K9ZW
Steve - drop me an email to the address in the right sidebar, just below the "About Me" box, "Contact Me"
DeleteSiGraybeard at gmail dot com
I'm more likely to see that email and not forget this conversation ever happened.
https://www.speedymetals.com/pc-4565-8371-34-od-x-0065-wall-tube-6061-t6-aluminum.aspx
ReplyDeletehttps://www.speedymetals.com/pc-4564-8371-34-od-x-0049-wall-tube-6061-t6-aluminum.aspx
There are silicon plugs used by people that do powder coating.
ReplyDeleteThey come in a variety of sizes.
They do not hold moisture like open cell earplugs....