PHD2 Guiding - Very Spikey Graph - Help!

[Andyb90]

I'm currently doing the belt mod. It's not exactly been plain sailing. I've got a post in the mounts section for some issues.

But hopefully it will be completed soon and I can test to see if it improves my guiding.

Andy.

 

 

[Andyb90]

I had a chance to do some testing the other week, now with the following changes:

• Completed belt mod
• Small mod to add extra weight (7.5kg) to the tripod - hoping for more stability.
• Changed finder guider back to ST80 - thought I'd give it a try to see if there was any difference.

I changed some settings in PHD2. I reduced RA and DEC aggression to 40, hysteresis was increased to 20, with exposure changed to 2.5 s. I also experimented with the dec guiding setting and ended up using 'south'.

My total RMS was between 1" and 0.75" for the session, I'd say on average about 0.9", which I think is an improvement. The graph and target certainly looked better than before.

Unfortunately my log file and test images got deleted when I tried to sync files between my imaging laptop and main computer :-(

Will do some more testing and post the results, but it looks like there may be some light at the end of the tunnel.

I think I'm also going to do the strip, clean and tune for the 2 axis as well. There is still definitely some play in the RA axis when the clutch is engaged.

I'm looking to upgrade the mounts saddle and use a Losmandy bar too.

Andy.

[Ishan Mair]

On ‎24‎-‎02‎-‎2016 at 19:08, kens said:

The guide log shows the periodic error on the blue line and it looks to be about 40" p-p which is on the high side. Checking it out in PecPrep the offending frequency is 380 seconds which is caused by the transfer gear. You could try improving the meshing of that gear.

Ken, I too have analysed my log on PECPro and found out problematic frequencies. Blame it on stepper and transfer gear.   It's so confusing for me : Stepper, transfer, idler, worm gear. It'd be great if you could post an image with labels here. Thanks.

 

On ‎24‎-‎03‎-‎2016 at 15:49, Andyb90 said:

I had a chance to do some testing the other week, now with the following changes:

• Completed belt mod
• Small mod to add extra weight (7.5kg) to the tripod - hoping for more stability.
• Changed finder guider back to ST80 - thought I'd give it a try to see if there was any difference.

I changed some settings in PHD2. I reduced RA and DEC aggression to 40, hysteresis was increased to 20, with exposure changed to 2.5 s. I also experimented with the dec guiding setting and ended up using 'south'.

My total RMS was between 1" and 0.75" for the session, I'd say on average about 0.9", which I think is an improvement. The graph and target certainly looked better than before.

Unfortunately my log file and test images got deleted when I tried to sync files between my imaging laptop and main computer :-(

Will do some more testing and post the results, but it looks like there may be some light at the end of the tunnel.

I think I'm also going to do the strip, clean and tune for the 2 axis as well. There is still definitely some play in the RA axis when the clutch is engaged.

I'm looking to upgrade the mounts saddle and use a Losmandy bar too.

Andy.

Hi Andy. I am having exactly the same problem with the same mount. I am still looking to solve this one. Hopefully, you have been able to get consistent good results after the belt mod. I might have to go down the same route. How freely did the RA axis of your mount rotate while balancing before the mod. Mine needs some force. So while I try to maintain a little East heavy configuration, it hasn't worked for me too well. I too see "gremlins" as Bruce mentions. I reduced the backlash in RA. While it did make things better, but still it isn't anywhere close to expectations. Gremlins are now cut to half size from 10 arc-sec to 5.

How difficult was it to mod your mount? Did you get another opportunity to check the performance? It'd be great if you could post a guide-log.

Thanks.

[Andyb90]

Hi Ishan,

The RA axis of my mount moves smoothly when balancing. The DEC axis is the same.

I had some issues with the belt modification, but managed to complete it. Here is a separate thread with details of the issues I had and how I resolved them.

I think there is variation between different HEQ5 units, as other people have had no issues at all with the belt mod.

Unfortunately due to the weather I haven't had another chance to test yet.

Since the last test I have also fitted an ADM dual saddle to my HEQ5 and I will be using a Losmandy plate to mount my scope. The set-up feels very solid and hopefully will add even more stability.

Will post again when I can do the next test.

Andy.

[Ishan Mair]

I have bookmarked your other thread. Its going to be useful for belt mod.