Strong winds strip actuator

[el bandido]

I get about 446 counts from 135w to 117w. It helps to have a few more counts to align the dish better. I think a bigger dish will have more counts than a smaller dish if everything else is equal except for dish size. My experience with old actuators is they have inconsistent counts at least part of the time. Positioner setup has been modified some in TNAP images to make it more useful for dish alignment and calibrating c band actuators.

Regardless of what the counts are, you got the dish moving again without spending hundreds of dollars. I call that a Success any day of the week. Congratulations!

[ArloG]

Awesome!
I have my 'cheat sheet' in a ring binder. Across the arc you find that sections of it need more or less pulses to travel so many degrees.
So even though I have some 40 sats located and stored already. I know that for...lets say 0 is my starting point for 127W. For easy resynching of the ASC-1 when things get out of whack.
From 127-125 I get 125 encoder pulses. Or right at 62-63 pulses/degree (don't know how to do the little degree character).
As I extend the actuator from 113 to 111. I get 142 pulses. Or 71/degree. Then 101-99.2 turns out to be 129 pulses. Or around 65/degree.

I have a 36" tube. It lets me cover 131W (damned trees) out to 40.5. Everything from zenith. Or let's say around 81W out to Britain. Counts get a bit freaky due to the actuator to dish mounting geometry.
So 58-55 turns out to be 66 pulses. 22 pulses per degree.
All of those stats are logged in my book-o-notes.
Since I scanned in all C band sats first and my ku lnbf is offset by 6 degrees from dish center. And my channel list is divided by C band first and then ku band. To keep the dish from swinging all over the place when peeking around. Interpolating where a sat 'should be' is a lot easier.

I have as many sats scanned and stored as I was able to. Even if they don't have viewable channels. Because sometimes they do have wild feeds. And transponders are added and deleted on a whim.
I just don't know how those dudes actully do discover wild feeds. If they sit there scanning the arc and scanning every single satellite looking for periodic channels, a newscaster picking his nose in dead air. I don't know.

[armadillo_115]

Slid the actuator UP about 1.5 inches today. (Believe I mistyped that it needed to slide DOWN in previous post) From 135w to 87w = 787 counts. Averaging 16.3 counts per degree. Counts increasing as it gets closer to zenith.

I may build an 8 magnet wheel for the other Uniden actuator instead of a 6. Not sure how that will work with magnets spaced closer together. No rush to get this other one done since it will be a spare.

Taking these actuator arms apart were MUCH easier than the SuperJacks! Remove the 3 screws connecting the arm to the motor, then the acme screw just screws all the way out.

The acme screw and arm had some dry rust and old grease powder. I wire brushed the acme screw pretty well and applied some rust remover. Greased it all up with some gear oil and a small dab of bearing grease. (All I had handy) Seems to ruin nice and smooth now. I need to add a grease fitting to the arm later. An accordion boot would be good as well.

Time to watch tv!

[ArloG]

I didn't get to add to my previous encoder rant. But briefly. You have to beware of neodymium magnets and spacing them closer to try and get a higher resolution.
The magnets are so strong and if you don't allow adequate spacing between them, the flux will overlap and the sensor will see it as one continuous field.
The idea is to get as much spacing as you can. If you have the room inside the motor to build a bigger wheel, you should.
And I mentioned I had started out with a certain size of magnet. I ended up getting the smallest ones. I think 2mm. You need that tight rise and fall of magnetic field.
Not so bad at slow speeds. Like when I bench tested mine with a 'scope. But once it was up to full speed on ASC-1 voltage. I started getting errors that didn't show at the slower speed.
And I used a hall sensor at first. A reed switch on high resolution was a no-go. The hall was very high speed with Schmitt trigger.
But still.....

Next. You really should check each and every magnet you use for equal strength. That was one of my issues. It took a bit to figure out.
Even with a precision divided encoder wheel. I was getting long and short pulses. It kind of flustered me.
I took the wheel out of the motor and benched it. Put it on a piece of wood with a hole drilled for a machine screw for a pivot.
"Borrowed" a sewing needle and thread. Taped the thread to the board at a distance where one of the magnets passing it would attract it.
Sure enough. Some magnets would lift the needle and attract it pretty good. Others didn't so much.
So. Hand select them for equal strength. And mark one side with a sharpie so you know what pole is what.

I have 3 incantations of magnet wheels. I'll dig those up and put up a few pics.
Two use 2mm disc magnets and one uses bar magnets.
Hall sensors have a window defined on them. That's in the data sheet for them. The 2 wheels using disc magnets should have been built with the discs around the perimeter of the wheel.
If you search for the key words 'neodyumium disc magnet flux characteristics' or something like that. You will see why.
Placement of the sensor. Whether hall or reed switch is a bit critical. Too high of a resolution on a small wheel with closely spaced magnets, for me, was just very inconsistent.
And. With closely spaced magnets. And many of them on a small wheel.
Actuator controls like the ASC-1 stop counting as soon as the relays in them deactivate. If you spun just the encoder wheel, the ASC-1 wouldn't care
Just a small motor coast will add up in errors. My 'scope has a pulse counter function. Compared to the ASC-1 and it hooked up at the sensor port. In a very short while with the actuator inside on my bench.
"Bumping" it like you would when peaking signals before saving the position. Added up 1, 2, 4 count discrepancies in a very short while.
The 'scope was always spot on. Because it has to be.
A dynamic brake consisting of that 24 VDC mini PCB mount relay with the center (relay armature) contacts out to the limit switch/motor. And the NC contacts having a .22 ohm resistor soldered to them.
With the ASC-1 motor wires connected to the NO contacts. All fitted inside the motor housing cover. Count errors reduced drastically. Not 100% when bumping the actuator E-W, W-E. But very very much better when just sending out a go-to from the receiver.

Enough. Merry Christmas!!
But. I'm going to turn you on to an optical encoder. Almost as easy as making a magnet wheel. Not one bit of tweaking for the sweet spot like for your reed/hall switch.
Just make sure the wheel slots are as accurate as you can make them. Assure that the thru beam is positioned so it either passes light or is blocked by the wheel slots.
And hope a spider doesn't decide to set up home on it. It's THAT good!

[armadillo_115]

Well it may not be pretty...

Fin_Actuator.jpg

Multiple layers of plexiglass stacked to mount the reed sensor. Reed sensor was crazy glued on lightly and tested. After it seemed to function ok, I epoxied the heck out of the whole sensor mount platform.

New magnet wheel epoxied to (trimmed down) optical wheel. Magnet wheel was a press fit, but I epoxied the center to the shaft for good measure.

I opted for strength over 'pretty' when it came to the epoxy job. I'll need to do fancier work if I open up a magnet wheel replacement factory. lol

[el bandido]

IMO, that magnet wheel should be left alone providing you have enough counts to accurately adjust the dish.

Coasting or improper counts are common actuator problems. A given actuator can only produce a certain amount of counts until you start having problems in other areas. Industrial actuators may have internal mechanical brakes which would provide a higher degree of accuracy. I think any actuator builder would tell you that actuators will have a certain amount of coast in them. If the counts get added into the coast, then there will be alignment problems. So if the dish is align-able with a decent degree of accuracy, then leave everything alone and enjoy it!

[armadillo_115]

IMO, that magnet wheel should be left alone providing you have enough counts to accurately adjust the dish.

Coasting or improper counts are common actuator problems. A given actuator can only produce a certain amount of counts until you start having problems in other areas. Industrial actuators may have internal mechanical brakes which would provide a higher degree of accuracy. I think any actuator builder would tell you that actuators will have a certain amount of coast in them. If the counts get added into the coast, then there will be alignment problems. So if the dish is align-able with a decent degree of accuracy, then leave everything alone and enjoy it!

I don't plan to 'fix it' as long as it works. Besides, we need this up and running... not on the repair bench.

I may experiment with an 8 count magnet wheel on the other actuator though. I'd also like to be able to adjust the sensor height and the in/out direction.

[Fearless]

My conversion from optical to an eight magnet wheel and double counting glass reed switch.

VW Sensor.jpg

[armadillo_115]

Just an update:
After 17 months, my 'temporary' experiment with the homemade magnet wheel is still going strong.... knock on wood. Seems like the temp test can be ruled a success lol

[ArloG]

Stickin' with the optical. All winter long and not a single fart. Thing is. Too many triggers/rev. and you get cumulative errors from Slight (EB) armature coast down.
Wa-la! Add a DPDT relay to act as a dynamic brake. Stops it like putting Brembos on a fire-chicken.
.....now. about that bouquet channel listing always being in alphabetical order in v6.



Gearbox_Optical.jpgOptical_Cropped.jpg