Review of my CDK12.5

Topic starter

Jan 4, 2022

Dale Penkala:
Nicely done!

Dale

Thanks Dale, glad you liked it.

Wasn't really able to find many reviews on these before taking the leap.
I hope these reviews will be useful for others considering the CDKs.

Rouz,

Jan 4, 2022

Hi Rouz,

nice write up. 😀
I have the 14”. I have experienced some due problems due to the missing humidity sensor. Either it heats too little of over heats and causes tubus seeing. I am in touch with PWI and figuring out how to improve the PWI controller software e.g. getting the dew point data via ASCOM.

CS
Ruediger

Topic starter

Jan 4, 2022

Ruediger:
Hi Rouz,

nice write up. 😀
I have the 14”. I have experienced some due problems due to the missing humidity sensor. Either it heats too little of over heats and causes tubus seeing. I am in touch with PWI and figuring out how to improve the PWI controller software e.g. getting the dew point data via ASCOM.

CS
Ruediger

That's unfortunate. How come it was missing, was it an older model or thy just forgot?!

My dew controller (Delta T) dies a few weeks ago, sent it in, W replaced it in a few days and got it back.

I was using the Pegasus UPB to run the heaters, it worked but the Delta T does a better job. Perhaps they can send you a sensor and you can add it to your scope?

Best,

Rouz

Dave Erickson

Jan 4, 2022

Hi Rouz,
Very nicely done!
As always…
Thanks!

Best,
Dave

Topic starter

Jan 5, 2022

Hi Rouz,
Very nicely done!
As always...
Thanks!

Best,
Dave

Thank you Dave, appreciate it!

Best,
Rouz

Jan 5, 2022

Ruediger:
Hi Rouz,

nice write up. 😀
I have the 14”. I have experienced some due problems due to the missing humidity sensor. Either it heats too little of over heats and causes tubus seeing. I am in touch with PWI and figuring out how to improve the PWI controller software e.g. getting the dew point data via ASCOM.

CS
Ruediger

That's unfortunate. How come it was missing, was it an older model or thy just forgot?!

My dew controller (Delta T) dies a few weeks ago, sent it in, W replaced it in a few days and got it back.

I was using the Pegasus UPB to run the heaters, it worked but the Delta T does a better job. Perhaps they can send you a sensor and you can add it to your scope?

Best,

Rouz

Hi Rouz,

it is missing by design. Neither the EFA nor the Delta-T Unit has a humidity sensor, which is a design flaw. This might be OK in some climate conditions, but it is not working here. e.g. when setting the main mirror 2C over ambient and it is e.g. 10C ambient and mirror at <12C it starts heating, though the dew point is maybe at 1 degree, since it is very dry. So you have unneeded heating which leads to tubus seeing,
Without having an information bout the actual dew point you heat based on guessing. The delta temperature is required but not sufficient. I have provided them tons of logs where this concept is failing by design. Even succeeded in making it cooling and heating at the same time.

PWI agreed on that, but only very few people run these instrument under my environmental conditions So this problem has no high prio. I joked and suggested to drill drainage holes in the main mirror tube... Was not their favorite solution

CS
Rüdiger

Helpful Insightful

Topic starter

Jan 5, 2022

Ruediger:
Ruediger:
Hi Rouz,

nice write up. 😀
I have the 14”. I have experienced some due problems due to the missing humidity sensor. Either it heats too little of over heats and causes tubus seeing. I am in touch with PWI and figuring out how to improve the PWI controller software e.g. getting the dew point data via ASCOM.

CS
Ruediger

That's unfortunate. How come it was missing, was it an older model or thy just forgot?!

My dew controller (Delta T) dies a few weeks ago, sent it in, W replaced it in a few days and got it back.

I was using the Pegasus UPB to run the heaters, it worked but the Delta T does a better job. Perhaps they can send you a sensor and you can add it to your scope?

Best,

Rouz

Hi Rouz,

it is missing by design. Neither the EFA nor the Delta-T Unit has a humidity sensor, which is a design flaw. This might be OK in some climate conditions, but it is not working here. e.g. when setting the main mirror 2C over ambient and it is e.g. 10C ambient and mirror at <12C it starts heating, though the dew point is maybe at 1 degree, since it is very dry. So you have unneeded heating which leads to tubus seeing,
Without having an information bout the actual dew point you heat based on guessing. The delta temperature is required but not sufficient. I have provided them tons of logs where this concept is failing by design. Even succeeded in making it cooling and heating at the same time.

PWI agreed on that, but only very few people run these instrument under my environmental conditions So this problem has no high prio. I joked and suggested to drill drainage holes in the main mirror tube... Was not their favorite solution

CS
Rüdiger

Rudiger,

Ah sorry I though the ambient temp sensor.
I have similar conditions here in coastal Vancouver, 98% RH. I find the Pegasus UPB very useful as it has the RH sensor and calculates the dewpoint.
I usually run the primary 1.5 DegC over ambient we its that high. So far it seems ok but I see what you mean, if it was automated, on dry nights the primary could be say 0.8 or 1.0 degrees over ambient.
I just do it manually now.

Let me know if PW come up with a solution (other than drilling holes!).

Best,

Rouz

Helpful Respectful

Jan 5, 2022

Rudiger,

Ah sorry I though the ambient temp sensor.
I have similar conditions here in coastal Vancouver, 98% RH. I find the Pegasus UPB very useful as it has the RH sensor and calculates the dewpoint.
I usually run the primary 1.5 DegC over ambient we its that high. So far it seems ok but I see what you mean, if it was automated, on dry nights the primary could be say 0.8 or 1.0 degrees over ambient.
I just do it manually now.

Let me know if PW come up with a solution (other than drilling holes!).

Best,

Rouz

Hi Rouz,

I also started to run it almost manual - at least on weekends.
I also have the PA UPB and also an MGP Box. All devices provide dew point information via ASCOM. But no way to get the data used for controlling the heater. I have already raised the idea to integrate it into the PWI plugin in NINA, but again... Only few people have to deal with the problem.

Sure I will keep you updated.

Cheers
Rüdiger

Topic starter

Jan 5, 2022

Ruediger:
Rudiger,

Ah sorry I though the ambient temp sensor.
I have similar conditions here in coastal Vancouver, 98% RH. I find the Pegasus UPB very useful as it has the RH sensor and calculates the dewpoint.
I usually run the primary 1.5 DegC over ambient we its that high. So far it seems ok but I see what you mean, if it was automated, on dry nights the primary could be say 0.8 or 1.0 degrees over ambient.
I just do it manually now.

Let me know if PW come up with a solution (other than drilling holes!).

Best,

Rouz

Hi Rouz,

I also started to run it almost manual - at least on weekends.
I also have the PA UPB and also an MGP Box. All devices provide dew point information via ASCOM. But no way to get the data used for controlling the heater. I have already raised the idea to integrate it into the PWI plugin in NINA, but again... Only few people have to deal with the problem.

Sure I will keep you updated.

Cheers
Rüdiger

Rudiger,

I think it is an excellent idea, given the price of the DeltaT and EFA combo, a RH sensor would have been great.

Lets see if they come up with an update or something, but as you said, not many people have this concern.

Best,

Rouz

Jan 5, 2022

Hello,

I have a CDK12.5 and was also wondering about the above. What I currently do is that I use the PWI 3 software to ensure the heaters cannot come on before 4am. In my experience and region, Dew is more an early morning issue. This at least avoids the heat + fan issue. I was wondering if one could control directly the PWI heaters. For example, from EAGlE PC +ECCO you can have dew and temp calculated and control due heaters. I wonder if I could connect directly to the heaters input on the back of the PWI and avoid the Delta T but I don't want to damage the electronics.
Another option is the launch the PWI software only when the Due point is reached within X degrees. This can be done from Voyager via dragscript. Dew and temperature from the above ECCO can be set as environmental variables than can trigger an event such as launching software (PWI).
Frederic

Helpful

Jan 5, 2022

Another option is the launch the PWI software only when the Due point is reached within X degrees. This can be done from Voyager via dragscript. Dew and temperature from the above ECCO can be set as environmental variables than can trigger an event such as launching software (PWI).
Frederic

Hi Frederic,

yes, after the discussion with Kevin (the PWI SW author) he had introduced the direct web API some time ago. But this is only a work around. I would appreciate to have a proper working SW.,

Not lunching the PWI SW is not an option, since you loose the focuser control. Also you have no data logging of the sensors.
So I would deeply appreciate, they would do it right and not halfhearted. But it looks like I am not the only one who notices some functional lags.

I will drop a mail to Bill from PWI support. Maybe I can convince them to have a serious look into it.

CS
Rüdiger

Topic starter

Jan 6, 2022

When my Delta T was being repaired Bill said its ok to use any regular dew heater controller.
I was using the Pegasus to control the CDK heaters (manually) so you can control the heaters without the PW controller.

Jan 6, 2022

When my Delta T was being repaired Bill said its ok to use any regular dew heater controller.
I was using the Pegasus to control the CDK heaters (manually) so you can control the heaters without the PW controller.

Many thanks for the info. This is very good to know.
but one problem still remains: you can not compare CDK sensor readings e.g. M2 to dew point. Since usually the mirrors get colder than ambient that is critical. So you can choose between two problems at lest.

Jan 6, 2022

Re the direct web API, is there some documentation available on that ? I couldn't find it.
Thanks

Jan 6, 2022 · Edited: Jan 6, 2022

Re the direct web API, is there some documentation available on that ? I couldn't find it.
Thanks

Hi Fredd,

I have only what Kevin has mailed me. But I will share it quickly. As far as I know there is no public documentation.
It works with version >= 3.5.3.

CS
Rüdiger

Quote:As a first pass at a scheme that will work better for you, I have added calls to the HTTP server hosted within PWI3 that allow you to override the heater settings.So now, for example, you can navigate to a URL like this:

http://localhost:55555/?device=heater&index=0&mode=on&power=50

to turn on the primary heater (index=0) and set it to 50% power. Or you could turn off the secondary heater (index=1) like this:

http://localhost:55555/?device=heater&index=1&mode=off

Similarly, you can force the fans to be off like this:

http://localhost:55555/?device=fans&mode=off

And you can switch the fans back to their normally-configured operating mode like this:

http://localhost:55555/?device=fans&mode=normal

( This is basically equivalent to checking/unchecking the "Ignore Config and Set Fans Off" checkbox in the GUI.)

Helpful

Jan 6, 2022

Thanks. Looks very limited and not useful in practice.

Jan 6, 2022

Thanks. Looks very limited and not useful in practice.

Yes, this was also my impression. I had reflected that to Kevin and Bill too. I am just drafting the mail to Bill and include the link to this discussion here.

CS
Rüdiger

Jan 6, 2022

it seems there are not many solutions :
- Change Delta T box to allow for humidity / dew point. Allow software to read such info from elsewhere
- Create some kind of PWI ASCOM Switch you could use with other capture software. May be complicated.
- Much more detail API and hope someone develops tools on the back of that.
Frederic

Jan 6, 2022

it seems there are not many solutions :
- Change Delta T box to allow for humidity / dew point. Allow software to read such info from elsewhere
- Create some kind of PWI ASCOM Switch you could use with other capture software. May be complicated.
- Much more detail API and hope someone develops tools on the back of that.
Frederic

You are right. I have just asked Bill and Kevin to recheck on option 1. Since it is not rocket science to read ASCOM dew point from environmental hub.
I have been discussing this now for more than one year but it has no priority. Kevin provided some js script to read ASCOM and trigger heaters based on that, but this is not a maintainable and reliable solution. I need a solution which is supported and I can rely on. I have lost too much data to continue to tamper around with workarounds.

Let's see what Bill and Kevin will reply. I keep my fingers crossed, when they read I am not the only one.

CS
Rüdiger

Dale Penkala

Jan 6, 2022

I’m just sitting here in the back following this thread for the simple reason PW is literally 1-1/2 hr drive and I toured there facility.Personally for the cost of these instruments these issues I would think SHOULD take priority! I’ve considered these scopes possibly down the road if finances would allow, but boy this makes me a bit more leary about these scopes and their support.

I hope you guys get these issues figured with PW! Instruments that are in this price category should NOT have the issues your describing!

Dale