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Has anyone mounted a powered usb hub on the top of their OTA that then runs to their computer?

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#26 DanMiller

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Posted 15 April 2024 - 09:25 PM

I find the biggest connection problems are with long cables subject to movement.  For the last year I have had a usb-3 hub mounted on the top bar of my scope.  As a result, I use very short cables and few connection issues.  I used a Pegasus PBA on another rig and have found it so good that I just bought a second one.  It has now replaced the USB hub on top of my main OTA.  Unlike Jim, I have absolutely no issues with either PBA.  They are insanely overpriced though.

Oh, I am sure my long cables are my problem. I have no doubt. 

 

Dan



#27 bignerdguy

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Posted 15 April 2024 - 11:21 PM

And you don't have any data dropouts issues?  What range extended are you using?

For comparison I have a 50' USB cable that has an unpowered repeater built into the center of it.  Since the USB hub and PC it is attached to are powered the cable does not need to be, for the equipment i run it hasn't had any issues.  I had to make sure the hub was powered and it needed to be a USB 3.0 one for it all to work.  In truth i don't remember if the cable was USB 2.0 or 3.0 however it works fine for the length. Some of the USB 3.0 cables out there are powered and should work as well.


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#28 TelescopeGreg

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Posted 15 April 2024 - 11:48 PM

My rule is to not mount anything on the scope that doesn't have to move in order to function.  When I used a USB hub, it was down on the eyepiece tray on the tripod.

 

If you MUST put it up there, mount it as low and central as possible, so under the primary mounting rail next to the rotisserie would be best.  The tradeoff is that the cables weigh something, too, so long runs can add up.

 

This is all about minimizing the moving inertia of the scope.  Inertia affects your guiding, and inertia goes by the mass times the square of the distance to the pivot point.  When you square something it gets big really fast; double the distance and you have 4x the inertia.  So the worst place is on top of the scope.  Worse still is on top at one end or the other. 



#29 Fegato

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Posted 16 April 2024 - 02:16 AM

I use the Pegasus USB hub. I don't have the advanced all-in-one model, but have it mounted on top of a separate powerbox micro (attached with velcro strap). This latter is mounted on one of the Buckeyestargazer losmandy mount plates on top of my OTA which works very well - he has lots of mounting solutions.



#30 Oort Cloud

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Posted 16 April 2024 - 01:00 PM

And you don't have any data dropouts issues? What range extended are you using?


No drops because it's USB2. You can already go 15-20ft with v2 without using active cables. USB3 is limited to about 6ft in comparison.
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#31 Oort Cloud

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Posted 16 April 2024 - 01:02 PM

I forgot to add that I will be ordering a flattener also. so, with 3 things being added already to the OTA. Another zwo shoe, metal finder scope, and the flattener. I have to get an idea how the mount will deal with that weight. So, I think in the beginning. I will be mounting the powered USB on a tripod leg or someplace like that. Not going to do a lot for my cable mess in the beginning. But it will allow me to get everything balanced with the other additions. Then I can deal with the USB hub possibly going on the OTA.

I find if I try to do too many things at once. It just isn't a good thing. Do things in order of priority. Flattener and guide scope first. The guide scope is already on the OTA, so that shouldn't cause issues. Then add the finder scope once and make sure things are balanced and the mount is ok with that. Then look to move the hub on the OTA.

I know, this will take time. But if I see problems, I will know what is causing them.

Dan


Apologies if I missed this in earlier posts, but in the age of plate solving, what is the point of putting the extra weight of a finder on an imaging scope? I get by fine without one, as most do. Curious if there is some niche use case that I'm not considering.
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#32 Jim Waters

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Posted 16 April 2024 - 01:33 PM

During mount 'Modeling' on stars in the East and West you may be off on the initial set of stars.  A red dot finder or a finder scope helps with the initial alignment.  I usually don't need one.



#33 don314

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Posted 16 April 2024 - 03:26 PM

I used a composite floor tile bolted to the top of the OTA rings.  I then mounter the focuser controller, USB hub (Startech, 4 port, 12VDC), and dew heater to it using ty-raps.  I made a custom power harness (red/black wires in photo) with a Anderson power pole connector spliced to the power plugs for the USB hub, dew heater, filter wheel, main camera, and focuser controller.    I have one power cable and one USB cable in a single jacket coming off the OTA.  Been working find for 5+ years.  Since the photo was taken, I added a strap on the Dec axis to hold the USB & power harness to relieve stress on the USB connection to the hub. I use a laptop computer next to the OTA. .2 SVQ100 IMG_3778 Small.jpg


Edited by don314, 16 April 2024 - 03:27 PM.

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#34 DanMiller

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Posted 16 April 2024 - 04:20 PM

I was imaging last night and had gotten my guiding into really good levels for my mount.  It's old and cranky, like me.  But I would have really nice lines with guiding then all at once it would spike for something like 3 images.  Then level out again.  I really need to get a handle on my cables so I can rule that out as part of the problem.  I have to seriously think about this.  I am getting tired of not knowing what is going on and you can only do so much with software tweaks.

 

Dan



#35 CharLakeAstro

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Posted 16 April 2024 - 04:43 PM

Using a PPBA - which is also a USB hub.

I use an extra-long dovetail bar for balancing scope forward,  and there was enough space on the DV to mount it directly

 

QwPqQPyl.jpg


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#36 limeyx

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Posted 17 April 2024 - 03:30 AM

My rule is to not mount anything on the scope that doesn't have to move in order to function.  When I used a USB hub, it was down on the eyepiece tray on the tripod.

 

If you MUST put it up there, mount it as low and central as possible, so under the primary mounting rail next to the rotisserie would be best.  The tradeoff is that the cables weigh something, too, so long runs can add up.

 

This is all about minimizing the moving inertia of the scope.  Inertia affects your guiding, and inertia goes by the mass times the square of the distance to the pivot point.  When you square something it gets big really fast; double the distance and you have 4x the inertia.  So the worst place is on top of the scope.  Worse still is on top at one end or the other. 

The inertia is one thing but with a mount with through-the-mount cabling, having the hub or similar up on the OTA can be one good way to avoid any dangling cables that drag and snag and be affected by wind etc so there are definitely tradeoffs



#37 GR-Amateur

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Posted 17 April 2024 - 09:16 AM

A better view.… Balance wise, inertia wise and from cable snug and practical point of view thought it’ll perform nicely and it did. The hub is connected to a 5m active usb cable, never had a problem over the last couple of years, multiple sessions, laptops, setups etc. 

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  • IMG_8706.jpeg

Edited by GR-Amateur, 17 April 2024 - 09:22 AM.

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#38 DanMiller

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Posted 17 April 2024 - 09:19 AM

Ya know

 

Apologies if I missed this in earlier posts, but in the age of plate solving, what is the point of putting the extra weight of a finder on an imaging scope? I get by fine without one, as most do. Curious if there is some niche use case that I'm not considering.

Honestly, because I do want to do some visual.  Or rather, I want to try it now that I have a telescope instead of just imaging with lenses.  I already have eye pieces and, a Barlow along with the finder scope.  If I find that I don’t like visual, I can always remove the dead weight.

 

That brings up another idea for the USB hub.  How about mounting it on the shoe on the side of the OTA where I have my guide scope now?  I have no clue how I could do that, but that would be a perfect place for it.  Out of the way, close to all the USB devices.  Kind of like that idea if I can figure out how to mount it.

 

Dan



#39 TelescopeGreg

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Posted 17 April 2024 - 11:53 AM

A better view.… Balance wise, inertia wise and from cable snug and practical point of view thought it’ll perform nicely and it did. The hub is connected to a 5m active usb cable, never had a problem over the last couple of years, multiple sessions, laptops, setups etc. 

+1

 

Lots of stuff done right:

  1. Guide scope mounted low and in the center, over the axis of rotation with two points of support all the way to the scope
  2. Electronic focuser positioned in-line with the scope, not off to the side
  3. Imaging camera hanging down, parallel to the counterweight shaft instead of up or off to the side.
  4. USB hub on the bottom side of the mounting rail (i.e. as low as possible), opposite to the camera for a bit of counterbalance
  5. Cables tied down, not flopping around
  6. Counterweights bunched together and up the shaft a ways, not out at the end.


#40 ayadai

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Posted 18 April 2024 - 06:17 AM

I used double-stick tape designed for house numbers to adhere it to the side of the mount (the tape is applied to the area on the mount without printing). The hub is an Xcellon 7-port powered unit that runs on 12V supplied by the PSU or battery. The hub connects to the computer with a 10-foot non-powered USB 3.0 cable. It works fine with no dropouts.

 

IMG_20240418_183345_1.jpg


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#41 HappyGalaxymore

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Posted 18 April 2024 - 06:59 AM

Ya know

 

Honestly, because I do want to do some visual.  Or rather, I want to try it now that I have a telescope instead of just imaging with lenses.  I already have eye pieces and, a Barlow along with the finder scope.  If I find that I don’t like visual, I can always remove the dead weight.

 

That brings up another idea for the USB hub.  How about mounting it on the shoe on the side of the OTA where I have my guide scope now?  I have no clue how I could do that, but that would be a perfect place for it.  Out of the way, close to all the USB devices.  Kind of like that idea if I can figure out how to mount it.

 

Dan

If it has a dovetail mount, you could 3D print a mount that uses it like I did for my homebrew EAF.

 

IMG 5112

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#42 DanMiller

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Posted 18 April 2024 - 07:28 AM

I used double-stick tape designed for house numbers to adhere it to the side of the mount (the tape is applied to the area on the mount without printing). The hub is an Xcellon 7-port powered unit that runs on 12V supplied by the PSU or battery. The hub connects to the computer with a 10-foot non-powered USB 3.0 cable. It works fine with no dropouts.

 

attachicon.gif IMG_20240418_183345_1.jpg

I have some heavy-duty Velcro that I use on the tripod legs to hold the power strip.  I also dumped the mounting bracket for the hand controller and use that tape for it.  I have to run a RJ9 to USB cable from the hand controller, and when I used the mounting bracket, the cord would get kinked and ultimately would fail.  So, I used Velcro to hold it.  Works really well to be honest.

 

I have a question though.  Ok, no matter where I mount the USB hub.  Yes, all the peripherals will plug into that.  But you still have the USB cable running from the hub to my laptop.   I am ordering a 6-foot USB cable to run from the hub to the computer, so there should be room.  But is this going to snag also when the mount slews to the far points of S/E/W of the compass?

 

Dan



#43 ayadai

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Posted 18 April 2024 - 12:27 PM

I have some heavy-duty Velcro that I use on the tripod legs to hold the power strip.  I also dumped the mounting bracket for the hand controller and use that tape for it.  I have to run a RJ9 to USB cable from the hand controller, and when I used the mounting bracket, the cord would get kinked and ultimately would fail.  So, I used Velcro to hold it.  Works really well to be honest.

 

I have a question though.  Ok, no matter where I mount the USB hub.  Yes, all the peripherals will plug into that.  But you still have the USB cable running from the hub to my laptop.   I am ordering a 6-foot USB cable to run from the hub to the computer, so there should be room.  But is this going to snag also when the mount slews to the far points of S/E/W of the compass?

 

Dan

The range of motion at the side of the mount is small and restricted to one axis, so there's little chance of a snag, as long as the cable to the computer is long enough and the computer is on the same side of the mount as the hub. Unless your computer is relatively far from the mount, 6 feet should suffice.


Edited by ayadai, 18 April 2024 - 12:30 PM.


#44 ChiTownXring

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Posted 18 April 2024 - 12:32 PM

I have been mounting my Powered USB hub and Pegasus Astro Pocket Powerbox on my OTA's from the beginning. I only have 2 cables that come off of the rig. One is the long USB cable that goes to my laptop and the 2nd one is the power for the mount. This setup allows me to get up and running within 15 minutes and I setup on my back deck every night that I have clear skies and for me it just works. I have marked were the tri-pod legs go so I am very close on my PA every time also.

 

med_gallery_339264_15021_83817.jpg

 

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