Re: Manage Cables Which Plate to Use for Top Mount Hardware?


Dale Ghent
 

On Nov 7, 2020, at 8:56 AM, Terri Zittritsch <theresamarie11@gmail.com> wrote:

Dale, thank you for the detailed and thoughtful response and information... like you, the focuser is my biggest concern, second is dew control. I like the Dew Busters capability and will have to take a look at the manual for the Pegasus.
The auto-dew feature on the UPBv2 is a bit ham-fisted at the moment, but it will get some improvements according to Evan of Pegasus.

I was also contemplating a Dew Buster as well before getting this, with the Dew Buster's auto-dew logic and that it places thermocouples up where the dew straps are to take the OTA temperatures and base its power level on that. The UPBv2 is different in that it has its own temperature+humidity sensor but it's not near the optics (although you can place it wherever its length of cable allows you); it's very much reflective of the ambient air around the OTA, not the temperature /of/ the OTA.

But really, in the end that doesn't seem to matter. The UPBv2 seems to ramp up the dew strap power output early enough such that dewing has never been a problem. Like I mentioned before, I'll set my rig up in the afternoon and just let it chill until it's time to start imaging later in the night. I just set the auto-dew to on and go about my day, have dinner, play with the kid, wrestle him to bed, clean up, and finally when it's astro-dark and I can turn my attention back to imaging, the dew heaters are already on with power output in accordance with the how close ambient temperature is to converging with the dewpoint.

I say it's ham-fisted in that it's very coarse in its incremental ramp up, and it seems sometimes that it will ramp up too fast and drive the dew straps at higher outputs that is really necessary for the conditions. One tactic is to let it auto-dew early in the evening, then turn the feature off and manually set the power output for each strap in accordance with your own intuition. The next version of the UPBv2 control app will have a new "Auto-Dew Aggressiveness" setting which will let you control this more. It's already available in an update to their smaller PPA product, and Evan at Pegasus says that it'll appear in a UPBv2 update soon as well. For what it's worth, I use Dew-Not and Kendrick straps, and the dewing levels I experience are typical of what you'd find in a mid-Atlantic suburban environment.

/dale

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