Date   

Re: Advice for someone considering purchasing a well used AP900GTO

George Lutch
 

From watching youtube it appears that you just loosen the adjustment screws on the worm housing and wiggle it followed by applying slight pressure to mesh the gears as you tighten the adjustment screws.


Re: Advice for someone considering purchasing a well used AP900GTO

Charles Thompson
 

PHD2 guide assistant has the option to measure backlash. I do not know how accurate it is though. 





Thanks,
Charles

Sent from mobile device.


-------- Original message --------
From: "Emilio J. Robau, P.E." <ejr@...>
Date: 4/12/22 3:53 PM (GMT-06:00)
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Advice for someone considering purchasing a well used AP900GTO

[Edited Message Follows]

George L,

If you have possession for a while, then for sure get Pempro and test out the PEC to see where you are at.  Pempro has a trial version that you can use.  I would feed the mount a new PEM curve if the owner will allow you to do that.   I am not sure but a trial may be available for APPC.  If you can get a hold of that, build a model and check the pointing.   

Also, just get the grease kit from AP when you purchase it.  Support the locals!  They have a kit that will last say three applications for sure.  I applied it to my 1600 and the 900 and have some left over.

Backlash is an interesting question on these older mounts.  I don't think my 1600 has any backlash.   Also, I think the backlash is also dependent on how well the gears are mashed.   I see APCC has a backlash setting on the initialization where you can set backlash in arc-sec on both RA and DEC.   Mine is set to zero but I often wonder if I can improve the tracking even more by adjusting that variable.   I am curious to see what tests people do to actually determine if a setting other than zero is appropriate.

I also wonder if the backlash setting on Ray's V2 driver sets the variable immediately after you enter the value and close out the ASCOM driver.  Not sure on backlash and interested in any input.


Re: Advice for someone considering purchasing a well used AP900GTO

Emilio J. Robau, P.E.
 
Edited

George L,

If you have possession for a while, then for sure get Pempro and test out the PEC to see where you are at.  Pempro has a trial version that you can use.  I would feed the mount a new PEM curve if the owner will allow you to do that.   I am not sure but a trial may be available for APPC.  If you can get a hold of that, build a model and check the pointing.   

Also, just get the grease kit from AP when you purchase it.  Support the locals!  They have a kit that will last say three applications for sure.  I applied it to my 1600 and the 900 and have some left over.

Backlash is an interesting question on these older mounts.  I don't think my 1600 has any backlash.   Also, I think the backlash is also dependent on how well the gears are mashed.   I see APCC has a backlash setting on the initialization where you can set backlash in arc-sec on both RA and DEC.   Mine is set to zero but I often wonder if I can improve the tracking even more by adjusting that variable.   I am curious to see what tests people do to actually determine if a setting other than zero is appropriate.

I also wonder if the backlash setting on Ray's V2 driver sets the variable immediately after you enter the value and close out the ASCOM driver.  Not sure on backlash and interested in any input.


Re: Advice for someone considering purchasing a well used AP900GTO

George Lutch
 

So much great advice.  I even went back via search and determined the correct grease to use.  The person selling the mount is going to let me test drive it for a week so I should see if there are any issues with it over that amount of time. 
Any advice on adjusting backlash out?


Re: Advice for someone considering purchasing a well used AP900GTO

Emilio J. Robau, P.E.
 

Thanks for the clarification.   I will touch and not snug.


Safety Slew and CP3 mounts?

Jeffc
 

 I was wondering about Safety Slew in the context of CP3 mounts.  
First tho, I had a question: .What is the purpose of the “safety slew”?


When counterweight is “up”, the backend of the OTA is probly in front of the pier.   If the DEC axis were to rotate (as it does when slewing as a result of a “goto”) , the backend of the OTA (eg camera) could crash into the pier.  So the initial part of the slew from a CW up position is RA only movement… then the DEC will slew when the CW is in a “safe range”.  

My next question was if the CP3 w/ V2 chip supports Safety Slew … and sadly it seems it does not.   Good to know (and I’m surprised at myself for missing this detail.)

However… does APCC (or the V2 driver) compensate for the CP3, and implement the Safety Slew logic? 
It seems like it might (but I might need to read the manual a bit more to be sure).


Usually with the AP 1200/CP3-V2 I semi manually slew to objects, and if in a CW UP position, “manually” slew away from the pier first before doing a goto.   

I suppose the CP4 would help here when using the AP keypad, but it would probably also be better when using APCC etc. 

Thx for any clarifications/ corrections.
-jeff
_._,_._,_


Re: Advice for someone considering purchasing a well used AP900GTO

George
 

Emilio,

 

Touch them…do not snug them.

 

Regards,

 

George

 

George Whitney

Astro-Physics, Inc.

Phone:  815-222-6538 (direct line)

Phone:  815-282-1513 (office)

Email:  george@...

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Emilio J. Robau, P.E.
Sent: Tuesday, April 12, 2022 3:42 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Advice for someone considering purchasing a well used AP900GTO

 

Thanks Chris,

Roland was able to understand what I was talking about.   They are the shaft dampers.


Re: Advice for someone considering purchasing a well used AP900GTO

Emilio J. Robau, P.E.
 

Thanks Chris,

Roland was able to understand what I was talking about.   They are the shaft dampers.


Re: Advice for someone considering purchasing a well used AP900GTO

Christopher Erickson
 

If the knobs are silver they could be the locks for the dovetail for taking the mount into two halves. Those need to be tight.

"Always take the high road. There's less traffic."

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii


Virus-free. www.avg.com


On Tue, Apr 12, 2022 at 10:36 AM Emilio J. Robau, P.E. <ejr@...> wrote:
Thanks Roland.  I have them snug but not tight.


Re: Advice for someone considering purchasing a well used AP900GTO

Emilio J. Robau, P.E.
 

Thanks Roland.  I have them snug but not tight.


Re: Advice for someone considering purchasing a well used AP900GTO

Roland Christen
 

They are shaft dampers with Teflon tips. They should not be tight, but just gently touching. Shaft dampers were commonly used back some 30 years ago to take slack out of shafts that were held by standard ball bearings that were not pre-loaded. The dampers put pressure on the shaft but still allow it to rotate at the sidereal rate. Too much pressure and the shaft will stall the motor.

We recently had an old mount come back where the damper was tightened by a crowbar. It was so tight we could not back it off without using a ton of force. The complaint was that the motors would stall and not track consistently. Yes indeed, that's what happens.

Nowadays mount bearings are preloaded, so no dampers needed.

Rolando

-----Original Message-----
From: Emilio J. Robau, P.E. <ejr@...>
To: main@ap-gto.groups.io
Sent: Tue, Apr 12, 2022 2:55 pm
Subject: Re: [ap-gto] Advice for someone considering purchasing a well used AP900GTO

A question for Roland if he is still there relevant to the 900.  What are the knobs that are associated with the axis that seem to be locks but are not really locks. What is their function and how tight do they have to be?

--
Roland Christen
Astro-Physics


Re: Advice for someone considering purchasing a well used AP900GTO

Emilio J. Robau, P.E.
 

A question for Roland if he is still there relevant to the 900.  What are the knobs that are associated with the axis that seem to be locks but are not really locks. What is their function and how tight do they have to be?


Re: Advice for someone considering purchasing a well used AP900GTO

Emilio J. Robau, P.E.
 

Steve,

I think you are correct.  I have not tried to guide counter weight up just in case.  I have not tried to run a mile lately, just in case.


Re: Advice for someone considering purchasing a well used AP900GTO

Roland Christen
 

Make sure the Dec is balanced and it will track well. RA is not as important to get the balance just right.

Roland

-----Original Message-----
From: Steve Salvo via groups.io <sws105@...>
To: main@ap-gto.groups.io
Sent: Tue, Apr 12, 2022 2:51 pm
Subject: Re: [ap-gto] Advice for someone considering purchasing a well used AP900GTO

I believe Not all of the older mounts needed the DEC upgrade, only those mounts that showed tracking issues. George can certainly further explain if needed.

I have an older AP900GTO no issues, amazing mounts!

Steve


On Apr 12, 2022, at 15:29, George Lutch <glutch@...> wrote:

I am considering purchasing a well used AP900GTO CP3 with hand controller and am in need of advice on what to check on the actual mount prior to purchase. I want to be sure there are no major issues with it.  Any advice would be appreciated.

--
Roland Christen
Astro-Physics


Re: Advice for someone considering purchasing a well used AP900GTO

Steve Salvo
 

I believe Not all of the older mounts needed the DEC upgrade, only those mounts that showed tracking issues. George can certainly further explain if needed.

I have an older AP900GTO no issues, amazing mounts!

Steve


On Apr 12, 2022, at 15:29, George Lutch <glutch@...> wrote:

I am considering purchasing a well used AP900GTO CP3 with hand controller and am in need of advice on what to check on the actual mount prior to purchase. I want to be sure there are no major issues with it.  Any advice would be appreciated.


Re: Advice for someone considering purchasing a well used AP900GTO

Emilio J. Robau, P.E.
 

Greetings George,

I purchased a used 2003 2004 vintage AP900 and after a break in period for me that entailed getting used to it and switching out an older CP2 unit for a used CP3 unit I think I have it performing pretty well.   The main thing to look for after your observe the general condition is the serial number.    AP had an enhancement (or fixed an issue with counterweight up guiding) that was deployed after a certain serial number.   I don't recall the number but will look it up for you and post later.   If you can get a mount with a serial number higher than the magic number you are one step ahead of me.   I love my mount and I picked it up with a whole bunch of stuff and it looked brand spanking new.   It was primarily used by a visual observer so the wear was significantly less than say my 1600 in the observatory which is deployed every single moment in the fall through spring that I can get to collect data all night long.

I think the main thing is the serial number that indicates whether or not it has the dec fix.

I don't think you can go wrong with any AP 900, 1200, 1100, and 1600 mounts.  They are electro mechanical works of art.   

I don't think you have to upgrade the CP3 to CP4 since the CP3 allows you to deploy a model from APCC and you really want that functionality, so you will need to purchase APPC if you don't already have it.   Highly recommended contribution to Ray's artwork in my opinion.

My AP900 points as well as my 1600 which has the CP4 box.   Sometimes I just shake my head and don't believe that NINA does not have to make a correction on a nearby slew or just one correction when slewing across the sky on the plate solves.   Amazing performance.

You can take the cover off of the gear box and take a look at the condition of the gears and the actual lube itself.   Mine was older and caked on.  I purchased the kit and re-applied the lube and it sounds better.  You could take off the box itself and take a look at the main gear as well as the worm, but that is somewhat invasive to someone who already may have the PEC programmed and does not want you messing with it.  

After using my 900 without the through mount routing of wires, I can say that I would be satisfied with a 1200 also.   I like the through mount functionality for the wiring, but have come to learn that it is not that huge of an issue to control the cords,  This is especially true if you purchase a Pegasus power box, which I did and it is definitely one of y favorite gadgets and allows for a very graceful control of the cords.

Finally, I want to add that I power my mount separately from everything else connected to the camera, heater, focuser and so on and so forth.   I have found that the heaters draw some amps and mess up the mount a bit from time to time so I run separate power.  Some will tell you that it is not necessary and their systems work through the power box, but mine does not.

Don't think twice, buy the thing.


Re: How to start imaging with CW up?

Roland Christen
 

I do it all the time with scope under the mount pointing to an object 3 or 4 hours from the zenith toward the east. As long as the scope clears the pier it works very well. I simply set a meridian delay of 3 or 4 hours east so that the scope flips sides when I enter the object in either the keypad or with SkyX. The mount will do a safety slew (which takes 2 slews with a momentary pause in between) and the scope ends up underneath the mount. You want to be there by the mount to make sure that nothing gets snagged and no possibility of collision. You don't want to do this in a remote setup or in an automated setup using 3rd party software. Too much can go wrong.
If you don't want to change the meridian delay, you can also use the command "Flip Sides". However if you do any centering using co-ordinate commands (example MaximDL moves) then the scope will flip back to the original side. Keypad button moves, as well as APCC, SkyX button moves, all work fine.

Rolando

-----Original Message-----
From: Wayne Hixson via groups.io <wayneh9026@...>
To: main@ap-gto.groups.io
Sent: Tue, Apr 12, 2022 2:20 pm
Subject: [ap-gto] How to start imaging with CW up?

Still Trying to understand meridian limits and their effect on GO TO s. I’ve mapped east and west meridian limits (which are different). I have a lot of opportunity to start with the scope on east side of pier and eliminate need to do meridian flip. I’ve turned on Enable limits and permit CW up slews on E and W sides. I do not have limit to meridian checked. I had hoped to have initial go to’s within the E limits go with CW up, but my testing doesn’t seem to do this. Can it in fact be done? Thanks

wayne

--
Roland Christen
Astro-Physics


Advice for someone considering purchasing a well used AP900GTO

George Lutch
 

I am considering purchasing a well used AP900GTO CP3 with hand controller and am in need of advice on what to check on the actual mount prior to purchase. I want to be sure there are no major issues with it.  Any advice would be appreciated.


How to start imaging with CW up?

Wayne Hixson
 

Still Trying to understand meridian limits and their effect on GO TO s. I’ve mapped east and west meridian limits (which are different). I have a lot of opportunity to start with the scope on east side of pier and eliminate need to do meridian flip. I’ve turned on Enable limits and permit CW up slews on E and W sides. I do not have limit to meridian checked. I had hoped to have initial go to’s within the E limits go with CW up, but my testing doesn’t seem to do this. Can it in fact be done? Thanks

wayne


Re: Log Files

W Hilmo
 

In my workflow, I keep all log files indefinitely.

I store the output from each session in a ZIP file, including all images taken, logs, etc.  The raw log files can be large, but they compress down to almost nothing.  A single frame from my camera uses much more space than all of the logs from the session.

-Wade

On 4/12/22 5:57 AM, Steve Reilly wrote:

Is there a practical time allotment that we should keep our logs files? It occurs to me that over the years these files could consume a great deal of space on our imaging systems. And if there is that allotment is there a way to do this automatically? Main concern is those remote systems like the NUCs that may likely have fewer hard drives onboard. Between ACP, APCC, MaxIm, Weather Station, FocusMax, and so on the amount of HD space, no matter how cheap it is these days, racks up fast. Any ideas?

 

-Steve

 


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