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Rotators for loop antenna
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Let's talk about rotators for loop antennas. I hope it's not too much of an off topic?
Just got my cross parallel loop installed on cheap RCA rotator designed for TV antennas (VH226e).
My antenna is not too heavy but it's quite long and I feel that it's a bit too top heavy for this rotator bearings. I can see quite a bit of a shaft play when I shake it by hand. So, I either need to reinforce it or buy something else. I'd appreciate any recommendations for that matter.
Quick video:
Thank you,
Simon
KM6MUL |
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wn4isx
A ham friend uses a Phillips TV antenna rotator, probably the same guts as your antenna.
He added Allied Tube & Conduit 10-ft 12-Gauge Electro-galvanized Slotted Channel StrutHe cut the 10 foot long piece into 2 4 foot sections drove them into the ground about 2 feet,? and used the 2 foot to between them and used a PVC pipe just large enough for his mast to fit through.
It's been up 5 years now and we have ice in the winter and moderate to high winds in the spring.
The mast has near zero wobble
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I hope my description made sense.
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Thank you for this description. So if I understand you right your friend is using an additional Pi-shaped support above Philips rotator? I assume rotating mast comes out of rotator and goes up through the middle of the Pi's horizontal where it is supported some how? Did he use some sort of a bearing there? I was thinking about something similar but it will take a bit of an effort especially placed and fixed on a balcony. I wonder if buying a more heavy duty rotator will end up being an easier solution. Regards, Simon KM6MUL On Tue, Aug 20, 2024, 3:18?PM wn4isx via <wn4isx=hotmail.com@groups.io> wrote:
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wn4isx
He used PVC pipe cut lengthwise with hose clamps to compress the PVC for a "sort of snug fit." lubricated with silicon grease and fabricated an "umbrella" with a hole in it to keep out water. This was to keep the grease from washing out and to prevent rain water ingress that would lock things when the temps dropped below freezing. It is butt ugly but works. There are a variety of vertical support and cross members that'd work. The? "Allied Tube & Conduit 10-ft 12-Gauge Electro-galvanized Slotted Channel Strut" Is called uni-strut as a generic name by electricians and several different companies make similar or identical material. The advantage of? this stuff is they make specialized nuts that make assembly a breeze. The material is also heavily galvanized so it should last at least a decade before rust is an issue. ? The strut material is a bit pricy. One could use treated wood if they dug post holes, or galvanized pipe, I suspect 1" steel pipe would be strong enough. The strut material's shape adds to the stability of the buried section. I've seen commercial utility electric service entrance (tech speak for meter box) mounted "struts" that I know have been there for at least 30+ years. The Goodwill I "mine" once a month or so went in in the late 1980s and their service entrance is mounted on "struts. ? ? ? Note: One must be careful to not allow any DC to flow through the "Slotted Channel Strut" because that can strip off the zinc. If any negative DC current does flow, one must counter it by biasing the struts positive. The telephone company (when they used copper) used positive ground so electrolysis would deposit minerals on exposed wires and not reverse electro-plate the copper away. Positive current will cause the strut to rot away. ? ? |
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Yeah, I used unistruts/superstruts for some of my other projects...
Looks like he got quite a bit of a setup. I'm trying to avoid that. Maybe I just look into other more heavy duty rotators. Thank you for all this information! Regards, Simon On Wed, Aug 21, 2024 at 4:59?AM wn4isx via groups.io <wn4isx@...> wrote:
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wn4isx
Another option I thought of as I was cleaning out a box of stuff.
A few years ago our meter pole started to lean becasuse of moles.
I initially was going to use guy wires to hold it upright and bought some push in the ground plastic anhors for dogs. I doubted their strength and pushed one in to normal soil, put 20 feet of used climbing rope on the ring and 4 adults couldn't budge it. I suspect you could make a cheap temporaray support by using 10 feet of PVC pipe that would slide over your mast and maybe on of these anchors if the strongest wind comes from the west like around here, or use 3 at equally spaced 10 foot long guys.
We bought these at Pet Smart but I'm pretty sure you could use 14" scrap iron pipe to accomplish the same thing. This would get you through the winter while you search for a stronger rotator.
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If there is interest I'll post a photo of one of the anchors before I find a new home for them.
We have a cat who'd curl up and die of fright if we staked her out.
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Hi
If you got $300 or so available just go buy a yaesu 450 rotator.. job done, safe, looks good (Wife and Landlord friendly.) reliable and holds resale value. Have one here holding up tein 2m tagi’s and 10m yagi.. year old, looks as new and on Dartmoor so very open to high winds and rain ( and sun.) Job done, forget about, especially if you up high on balcony, last thing one needs is an antenna hanging from cable over someone’s head! $300 ( or so, mine i had buy bottom clamps.) well spent. Simon g0zen |
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That's a great idea! I was thinking about using some guy wires and
some piece of PVC over the mast... Cannot use ground for any mounts as my balcony is ~4m about ground surface and we have a garage right below it. But maybe I can use some wall attached eyelets somewhere around the balcony. I also found out that Yaesu makes a few nice thrust bearing for cases like that. These bearings can be hard mounted or guy wired and relatively inexpensive. I'm pretty new to rotators :) Regards, Simon On Thu, Aug 22, 2024 at 2:54?AM wn4isx via groups.io <wn4isx@...> wrote:
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Hi Simon,
Yep, totally agree and I'm Ok to spend more money on quality rotator. I was actually thinking about Yaesu G800DXA. That's one step up - should be holding even better. And looks like I really need just a motor (Yaesu sells it separately) as I can literally see my antenna through the window and have no need for precise azimuth control of the Control unit. Also it appears that newer Yaesu motors are DC (older ones were AC, like many other rotators). That means that I can just drive it with 2 wires by reversing polarity. Will keep me from drilling another hole through the wall (have extra 3 wire connection going through the wall already). But looks like it will be a good idea to still use a thrust mast bearing maybe 1-2 feet above the rotator. In the manual Yaesu states that rotating portion of the mast shouldn't be high, otherwise thrust bearing is needed. Although I don't have a 40m Yagi made of stainless steel... Regards, Simon KM6MUL On Thu, Aug 22, 2024 at 9:44?AM Simon via groups.io <ohhellnotagain@...> wrote:
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You can couple a short piece of pipe to the backside of the rotator mounting bolts with another set of mast clamps and run up another mast/pipe parallel to just under the loop. Then space another set of opposing clamps from that section to the rotating mast. Use a short section of PVC pipe around the rotating mast to provide discontiuity but allow rotation. Use green or lithium grease.? You will have enough to spend a little time adjusting the spacing just right?? This would a nice support bearing and take some of the stress off the rotor housing.
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Note that your rotor bearings are just sleeve bearings and have a lot of "slop" in them.? Your 2-loop array doesn't look to have more windload than a typical TV antenna, but in a windy area on top of a roof,it can provide additional support.
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Good luck,
Holmzie n2exg |
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