EQStar for my G11S

[SkyHiker]

About a year ago I decided to add a Losmandy G11S in addition to my AVX mount. I used the AVX successfully and enjoyed its simplicity and light weight, great to travel with, easy to use and quite capable. I can't quite recall why I wanted to upgrade, maybe I was momentarily insane, or I felt that I had to upgrade to a more capable mount. I believe I was thinking about getting an astro camera and needing higher resolution images for galaxies. I wanted to buy an American product to support our economy so I ended up with Losmandy. The G11S was reasonably affordable at the time, about $2.4K IIRC, so I drove to Burbank to pick one up.

The G11S is a mechanical piece of art. It is almost worth buying just to admire Scott Losmandy's craftsmanship! It does not have goto capabilities, just the basic Celestron tracking and guiding hardware. The G11S has excellent setting circles. So my routine was to polar align, then do a one-star alignment with the setting circles and manually slew to my target. It works but the goto was not always accurate. A one-star alignment is only accurate if there is no cone error. There were several times when it was not on target so I ended up taking pictures nearby to find the object, which is painful. Bottom line, without a goto system I might as well sell my G11S because it is too cumbersome to use. Right now it's sitting on my driveway, polar aligned, chained to an anchor out in the rain and the sun for months, unused.

Since I like tinkering with equipment much more than actually using it, and since I like bargains irrationally (money is not my problem, I just thoroughly dislike the feeling of overpaying for something), I decided on the EQStar goto kit by Astro-Gadgets. I put in the order. Alexander sent an email asking about if it was for a Gm8 or G11, I replied, and he will ship it within 3 days of ordering with a tracking number. So I expect to arrive in a week or so, maybe sooner.

The EQStar product looks pretty rudimentary but seems to have all the necessities. I found several CN threads about it, and it looked like if you can figure out the software, it should be fine. The manual recommends using EQMOD with a planetarium program through EQASCOM. This is where it gets interesting, since I would prefer using my Raspberry Pi that of course does not have ASCOM (and why on earth would we need a Windows-only, non-distributed solution). I can always use ASCOM to setup then use the Pi with lin_guider for autoguiding through ST-4, which is what I use now. So I asked Alex if INDI was supported. His reply was that INDI was supported through EQMOD, so it should not be a problem.

I don't want to bug Alex more than I need to so I concluded that EQASCOM and INDI are both implemented based on the Nexstar protocol and that the EQStar firmware is based on Nexstar, which is the main protocol for all Synta mounts (which includes Celestron). There only seem to be two communication protocols, LX-200 and Nexstar, so my guess is that EQStars is Nexstar-based. The EQMOD pages are not super clear about it. The news that any EQMOD-supported solution is supported, seems to imply that it is a Nexstar box.

When it arrives I will first have to assemble it, let's hope the motors fit easily. I will start with the wired solution through my PC using EQASCOM. Once I get that going I may try the WiFi connection still through EQASCOM; eventually I want to use the Pi but before this is useful I need to add the Ekos software, maybe upgrade to a Pi 4 (my current one is 2) and get a camera that can be controlled (unlike my Fuji X-a1). So, lots of work depending on how much punishment I choose. Right now I hope the stepper motors are adequate, let's see how it evolves. I will keep you posted.

[SkyHiker]

I just got the tracking number, it is currently in Kharkiv, Ukraine shipped with Ukrposhta. No word on expected arrival time...

[BamaDon]

Any update on this?

[SkyHiker]

Any update on this?

The Ukrposhta tracking status has been "Item has been processed outward office of exchange and already in transit to destination country" since March, 13! I have not bugged Alex yet because he's a nice guy, and the Corona crisis will delay everything. But OK let me shoot him an email...

[SkyHiker]

Any update on this?

The Ukrposhta tracking status has been "Item has been processed outward office of exchange and already in transit to destination country" since March, 13! I have not bugged Alex yet because he's a nice guy, and the Corona crisis will delay everything. But OK let me shoot him an email...

Alex replied. He asked Ukrposhta confirmed that the shipment was in the "transit zone". My guess is that this means it is released from customs and ready to be shipped, or is somewhere underway. They also said that normally such items are shipped with passenger planes. With the Corona virus crisis these planes are no longer flying so it has to be shipped by a combination of cargo planes and cars. Alex said he would keep me posted.

[SkyHiker]

The EQStar kit has arrived. It was a small package that fit in my mailbox. Inside are two smaller boxes, one with the motors and one with the controller, cables etcetera.

My son helped me with assembling the motors. I was pleased to see that they fit very well in the Losmandy mount, with the right screws. That's a major relief, I hate to have to make something fit! They come with flex couplers, which I like better than the Losmandy ones - it might reduce the DEC backlash.

It needs 12 V, my jump-starter worked fine for that. I had an old center positive connector that worked for it. Just trying it with the tiny hand controller ran the motors OK - the DEC one was a bit bumpy, even after I loosened everything up. Not sure if this will be a problem. The RA motor tracks by default, it makes a slight period wheezing sound. Eventually it will be controlled by the PC, maybe I can report back to that later this afternoon.

The controller is very light. I could just attach it with some Velcro, my son pointed me at some tube clamps that would let it use the standard Losmandy hooks - we will figure something out. It comes with a wireless, a serial to USB cable to connect with the PC.

Right now I'm reading up on how to use it with EQMod and will report back later.

[SkyHiker]

I got it working with EQMod and Stellarium for the most part. If I slew one motor at a time it is pretty smooth. In Stellarium I can see the circle moving to where it thinks it is going. I say that because the direction seems to be 90 degrees off, I presume there is some setting that I missed.

However if I let Stellarium slew to a star that I selected, it oftentimes slews 2 motors simultaneously. Because I have a bit of slack in the gears this results in a coffee grinder noise due to the resonances. Then when I slew back to the original parking position, I see it is 20 to 30 degrees off so it really loses a lot of steps when grinding coffee. I sent Alex an email about this, maybe there is a way to slew one motor at at time? Not a deal breaker because I can always slew manually one motor at a time, since the pointing location is clearly visible in Stellarium.

I have to say I again spent a lot of time messing with the worm gears of the Losmandy. I'm beginning to get fed up with that.

[SkyHiker]

The EQStar flex coupler was pressing the worm into the cog wheel. This caused the motors to bind up in RA frequently. I then figured out how to move the worm out by shimming some foil folded 3 times between the outer gear block and the frame. That helped a lot so I was able to slew smoothly at speed 4.

However at other speeds it sometimes still turned into a coffee grinder, and in RA I could hear a clicking sound, at speed 1 I could even see the gear jump during the clicks. I took videos and posted it to Alex of Astro-Gadget. He determined that the RA driver chip was bad and offered to send a replacement circuit board.

It will probably take another 2 months to arrive so until then I'll go back to the Celestron controller. Now that I figured out how to shim the gear it should work better.

I have to say, I should not have to spend hours on end figuring out how to adjust the gears time after time. The gear block needs to be pressed longitudinally towards the motor to keep the worm axis in place, then laterally to avoid play between the worm and the cog wheel. They illustrate this in a video on their YouTube channel. But it's easy to apply too much lateral pressure - or not enough - and either have the motors bind up or have backlash. Losmandy should give some guidelines and probably advise on how to shim it to work around the pressure problem.

[BamaDon]

Wow, that's turning into an experiment! Thanks for the effort.

It sounds like the Worm gear problem is with Losmandy, but the Grinding was A-G?

Agree that you shouldn't have to do all this work, esp. with a 2 month lead time.

[SkyHiker]

Wow, that's turning into an experiment! Thanks for the effort.

It sounds like the Worm gear problem is with Losmandy, but the Grinding was A-G?

Agree that you shouldn't have to do all this work, esp. with a 2 month lead time.

Yes it has turned into an experiment. The Losmandy mounts are great but require some DIY work on the worm gears. This is normal I'm afraid, and the EQStar has helped me with figuring this out because now I can finally slew over a large range with a motor and see if/where it binds up. Using shims will let me control the pressure much more consistently so it has been useful.

Hopefully Alex is right that the chip is faulty. When the board arrives I will have to do some soldering because it has a wire to a rear panel connector. So I will hold on to mine until it arrives and I've got it working properly. He just wants to do a post-mortem check on it, which is good.

[SkyHiker]

PS Don I don't know if you are on the Losmandy users group but it's a good resource. I started a thread on this and some people mentioned alternatives to EQStar, you may want to check that as well: https://groups.io/g/Losmandy_users/topi ... 0,31266916

[SkyHiker]

So the new EQStar board has arrived, and it works much better!

I still had trouble with the motors binding up but, working with Alex, I was able to figure out it was because of a lack of power. I don't need a whole lot more but if I plug in the power cord to my jump starter, that's enough to fix it. Alex also recommended new motors of 60 Ncm torque that I ordered meanwhile. The standard ones are 32 Ncm so going to 60 Ncm should help a lot too. Autoguiding works also.

The other issue is that the friction between the crown wheel and the worm can vary a lot. By moving the worm back and forth at a rough spot, it eases up a bit so I wonder if there is some clogged up grease or something. I will call Losmandy nest week about this. I may drive down there to show it. One thing I need from them is a lighter counterweight, why not pick it up and show them my EQStar stuff as well.

I had to practice my EQMOD skills, its idiosyncrasies used to throw me for a loop but now that I know them I can handle it.

[BamaDon]

Henk, I discovered the Losmandy Groups a couple of years ago, but thanks!

Will the 60 Ncm motors require *even more* power than the 32Ncm motors?

[SkyHiker]

Hi Don

Alex said the new motors use 640 mA. I don't know how much the old ones use because I don't have their P/N. At 12 V that's 2*12*0.64=15.36 W. My jump starter has 80 Wh so it's getting up there, about 5.3 hours with my Pi (about 2W). The manual has 80 Wh use cases but it also says 12 V DC with 12 Ah, that is 144 Wh so I suppose it means that the voltage drops quite a bit during use. Looks like I need a new power source for my trips.

BTW I switched from EQMOD on my laptop to Ekos on a Pi (used from my Android table by remote login), it works great and has lots of features!