fan operation without EFA

#...

· 3 likes

Ruediger:
Rouz Astro:
I see it does say "Primary" in the description.

And you are right Bill, it does not provide the primary but the backplate. You will need the EFA for that.
Pegasus said if they know the details they can make a wire to drive that focuser stepper motor with the UPB, no updates on that.

As for value, I can tell you the Pegasus UPB is about $650 and has about a page long list of features!

Rouz

This would make everyone happy - but this would cut their profit and that is why they won’t do it.

Even if they overcharge again probably a lot of people, including existing owners of EFA and DT, will still gladly pay, as no alternative exists. It is baffling why they choose to carry the baggage of their outdated design.

Edited ...

8.40 Rouz Astro #... · view views · 1 like
Yuxuan: Ruediger: Rouz Astro: I see it does say "Primary" in the description. And you are right Bill, it does not provide the primary but the backplate. You will need the EFA for that. Pegasus said if they know the details they can make a wire to drive that focuser stepper motor with the UPB, no updates on that. As for value, I can tell you the Pegasus UPB is about $650 and has about a page long list of features! Rouz This would make everyone happy - but this would cut their profit and that is why they won’t do it. Even if they overcharge again probably a lot of people, including existing owners of EFA and DT, will still gladly pay, as no other alternative exists. It is baffling why they choose to carry the baggage of their outdated design. *I wrote that in a review of the CDK12.5, also sent them a link: "The two electronic controllers are a bit bulky and expensive; I would have liked to see a sleeker box with a single USB cable." Rouz Like

8.40

#...

· 1 like

Yuxuan:
Ruediger:
Rouz Astro:
I see it does say "Primary" in the description.

And you are right Bill, it does not provide the primary but the backplate. You will need the EFA for that.
Pegasus said if they know the details they can make a wire to drive that focuser stepper motor with the UPB, no updates on that.

As for value, I can tell you the Pegasus UPB is about $650 and has about a page long list of features!

Rouz

This would make everyone happy - but this would cut their profit and that is why they won’t do it.

Even if they overcharge again probably a lot of people, including existing owners of EFA and DT, will still gladly pay, as no other alternative exists. It is baffling why they choose to carry the baggage of their outdated design.

*I wrote that in a review of the CDK12.5, also sent them a link:

"The two electronic controllers are a bit bulky and expensive; I would have liked to see a sleeker box with a single USB cable."

Rouz

18.93 Ruediger #... · view views
Rouz Astro: Yuxuan: Ruediger: Rouz Astro: I see it does say "Primary" in the description. And you are right Bill, it does not provide the primary but the backplate. You will need the EFA for that. Pegasus said if they know the details they can make a wire to drive that focuser stepper motor with the UPB, no updates on that. As for value, I can tell you the Pegasus UPB is about $650 and has about a page long list of features! Rouz This would make everyone happy - but this would cut their profit and that is why they won’t do it. Even if they overcharge again probably a lot of people, including existing owners of EFA and DT, will still gladly pay, as no other alternative exists. It is baffling why they choose to carry the baggage of their outdated design. *I wrote that in a review of the CDK12.5, also sent them a link: "The two electronic controllers are a bit bulky and expensive; I would have liked to see a sleeker box with a single USB cable." Rouz …and they ignored it, because „there are so many user who are happy with the existing solution“. /s They simply see no need for improvements. They are really genius in optics, but in electronics and SW they are pre-historic. Like

18.93

#...

Rouz Astro:
Yuxuan:
Ruediger:
Rouz Astro:
I see it does say "Primary" in the description.

And you are right Bill, it does not provide the primary but the backplate. You will need the EFA for that.
Pegasus said if they know the details they can make a wire to drive that focuser stepper motor with the UPB, no updates on that.

As for value, I can tell you the Pegasus UPB is about $650 and has about a page long list of features!

Rouz

This would make everyone happy - but this would cut their profit and that is why they won’t do it.

Even if they overcharge again probably a lot of people, including existing owners of EFA and DT, will still gladly pay, as no other alternative exists. It is baffling why they choose to carry the baggage of their outdated design.

*I wrote that in a review of the CDK12.5, also sent them a link:

"The two electronic controllers are a bit bulky and expensive; I would have liked to see a sleeker box with a single USB cable."

Rouz

…and they ignored it, because „there are so many user who are happy with the existing solution“. /s
They simply see no need for improvements. They are really genius in optics, but in electronics and SW they are pre-historic.

8.40 Rouz Astro #... · view views
Here is a screenshot of my temps. This was after about 4~5 hours of imaging, ambient had settled but the primary has rarely gets down to that temp, except maybe near the early hour before sunrise. I don't see the primary turn on and its always the secondary that needs heat. The fans are always on. That's got me thinking perhaps its not that critical to measure the primary temperature directly as it probably doesn't need all that much "control" but rather active cooling. I'm sure there are scenarios where you will need heat, for now its just the backplate temp. You could maybe just stick that sensor on the primary if you remove the backplate. Rouz Like

8.40

#...

Here is a screenshot of my temps.

This was after about 4~5 hours of imaging, ambient had settled but the primary has rarely gets down to that temp, except maybe near the early hour before sunrise.

I don't see the primary turn on and its always the secondary that needs heat. The fans are always on.

That's got me thinking perhaps its not that critical to measure the primary temperature directly as it probably doesn't need all that much "control" but rather active cooling.

I'm sure there are scenarios where you will need heat, for now its just the backplate temp. You could maybe just stick that sensor on the primary if you remove the backplate.

Rouz

18.93 Ruediger #... · view views
Rouz Astro: Here is a screenshot of my temps. This was after about 4~5 hours of imaging, ambient had settled but the primary has rarely gets down to that temp, except maybe near the early hour before sunrise. I don't see the primary turn on and its always the secondary that needs heat. The fans are always on. That's got me thinking perhaps its not that critical to measure the primary temperature directly as it probably doesn't need all that much "control" but rather active cooling. I'm sure there are scenarios where you will need heat, for now its just the backplate temp. You could maybe just stick that sensor on the primary if you remove the backplate. Rouz Hi Rouz, this might work in your case, but I have regularly the situation, that the primary is colder than the backplate. But what is worse, the real ambient temp is below dew point, and the backplate is much higher. The back plate is cooling down much slower, than the air temp drops. When it reaches actual air temp, already the water is poring out of the tube. Also keeping the fans on all the time is only an option when you have no neighbors. In my case it would take very little time that I get a unpleasant visit if I keep them running after 22h. Like

18.93

#...

Rouz Astro:
Here is a screenshot of my temps.

This was after about 4~5 hours of imaging, ambient had settled but the primary has rarely gets down to that temp, except maybe near the early hour before sunrise.

I don't see the primary turn on and its always the secondary that needs heat. The fans are always on.

That's got me thinking perhaps its not that critical to measure the primary temperature directly as it probably doesn't need all that much "control" but rather active cooling.

I'm sure there are scenarios where you will need heat, for now its just the backplate temp. You could maybe just stick that sensor on the primary if you remove the backplate.

Rouz

Hi Rouz,

this might work in your case, but I have regularly the situation, that the primary is colder than the backplate. But what is worse, the real ambient temp is below dew point, and the backplate is much higher. The back plate is cooling down much slower, than the air temp drops. When it reaches actual air temp, already the water is poring out of the tube.

Also keeping the fans on all the time is only an option when you have no neighbors. In my case it would take very little time that I get a unpleasant visit if I keep them running after 22h.

22.61 John Hayes #... · view views · 2 likes
Thanks John. The Primary mirror backplate data is supplied, but not the actual back of the mirror temp, which is in EFA. I guess I take half of what I was mad about back knowing this. They are not providing the exact data they claimed (primary mirror temp) but a rough approximation instead. I am curious to know if you have measured the difference in the backplate temp vs the primary mirror temp and found any linear relationship between the two? -Bill Bill, I’m not sure that it matters whether the sensor is on the backplane or on the back of the glass. Ideally, what you really want is the temperature of the front surface of the primary and neither sensor gives you that number. Your question is a good one and I don’t have an answer. The ultimate goal is to use the absolute minimum amount of heat that will prevent dew but you still have to add in some margin. The sensor on the rear of the secondary is probably providing the most useful data since it’s directly exposed to the sky—and indeed, it always shows the coldest temperature. You do have the ability to set different target temperatures for the secondary and the primary so there’s room to experiment a little. The bigger problem on my 20” is the location of the fans, which are only on the back plane. I think that they help a lot to increase convective heat exchange between the primary and the air to better offset radiative losses; however, they do almost nothing to dissipate thermal currents in front of the mirror. In my view, Planewave did a VERY poor job of engineering the thermal control components to work as a system. Allowing the focuser to be controlled by the thermal management system is great, but making the focuser a necessary component in the control system was just stupid. I also think that the price of the Delta-T controller is absurd both for what it is and for what it lacks. Even without the focuser, it is useable but it should have been SO much better—and they don’t utter a word about it when you order a system without one of their focusers. The frustrating thing is that PW doesn’t listen to their customers. I had a long discussion with them about the issue of dew control and they privately admitted to me that they are aware of the problems but they continue to do absolutely nothing about it. I love the people at Planewave and I’m extremely impressed by their success but I have seen so many ongoing, unaddressed problems that my next telescope is very unlikely to come from Planewave. John Like

22.61

John Hayes

#...

· 2 likes

Thanks John.

The Primary mirror backplate data is supplied, but not the actual back of the mirror temp, which is in EFA. I guess I take half of what I was mad about back knowing this. They are not providing the exact data they claimed (primary mirror temp) but a rough approximation instead. I am curious to know if you have measured the difference in the backplate temp vs the primary mirror temp and found any linear relationship between the two?

-Bill

Bill,
I’m not sure that it matters whether the sensor is on the backplane or on the back of the glass. Ideally, what you really want is the temperature of the front surface of the primary and neither sensor gives you that number. Your question is a good one and I don’t have an answer. The ultimate goal is to use the absolute minimum amount of heat that will prevent dew but you still have to add in some margin. The sensor on the rear of the secondary is probably providing the most useful data since it’s directly exposed to the sky—and indeed, it always shows the coldest temperature. You do have the ability to set different target temperatures for the secondary and the primary so there’s room to experiment a little. The bigger problem on my 20” is the location of the fans, which are only on the back plane. I think that they help a lot to increase convective heat exchange between the primary and the air to better offset radiative losses; however, they do almost nothing to dissipate thermal currents in front of the mirror.

In my view, Planewave did a VERY poor job of engineering the thermal control components to work as a system. Allowing the focuser to be controlled by the thermal management system is great, but making the focuser a necessary component in the control system was just stupid. I also think that the price of the Delta-T controller is absurd both for what it is and for what it lacks. Even without the focuser, it is useable but it should have been SO much better—and they don’t utter a word about it when you order a system without one of their focusers. The frustrating thing is that PW doesn’t listen to their customers. I had a long discussion with them about the issue of dew control and they privately admitted to me that they are aware of the problems but they continue to do absolutely nothing about it. I love the people at Planewave and I’m extremely impressed by their success but I have seen so many ongoing, unaddressed problems that my next telescope is very unlikely to come from Planewave.

John

8.40 Rouz Astro #... · view views
Ruediger: Hi Rouz, this might work in your case, but I have regularly the situation, that the primary is colder than the backplate. But what is worse, the real ambient temp is below dew point, and the backplate is much higher. The back plate is cooling down much slower, than the air temp drops. When it reaches actual air temp, already the water is poring out of the tube. Also keeping the fans on all the time is only an option when you have no neighbors. In my case it would take very little time that I get a unpleasant visit if I keep them running after 22h. *You are that close to the neighbors! I believe your mount is lot less noisy than my AP mount as well. The fans are surprisingly noisy given the small size, they must be high rpm models, PWM doesn't work but you could swap those fans out for slower more silent ones, even with PWM. I agree its best to have complete control of the system. I do use the backplate temp. to control the primary. Rouz Like

8.40

#...

Ruediger:

Hi Rouz,

this might work in your case, but I have regularly the situation, that the primary is colder than the backplate. But what is worse, the real ambient temp is below dew point, and the backplate is much higher. The back plate is cooling down much slower, than the air temp drops. When it reaches actual air temp, already the water is poring out of the tube.

Also keeping the fans on all the time is only an option when you have no neighbors. In my case it would take very little time that I get a unpleasant visit if I keep them running after 22h.

*You are that close to the neighbors!
I believe your mount is lot less noisy than my AP mount as well.

The fans are surprisingly noisy given the small size, they must be high rpm models, PWM doesn't work but you could swap those fans out for slower more silent ones, even with PWM.

I agree its best to have complete control of the system. I do use the backplate temp. to control the primary.

Rouz

8.40 Rouz Astro #... · view views · 1 like
John Hayes: Bill, I’m not sure that it matters whether the sensor is on the backplane or on the back of the glass. Ideally, what you really want is the temperature of the front surface of the primary and neither sensor gives you that number. Your question is a good one and I don’t have an answer. The ultimate goal is to use the absolute minimum amount of heat that will prevent dew but you still have to add in some margin. The sensor on the rear of the secondary is probably providing the most useful data since it’s directly exposed to the sky—and indeed, it always shows the coldest temperature. You do have the ability to set different target temperatures for the secondary and the primary so there’s room to experiment a little. The bigger problem on my 20” is the location of the fans, which are only on the back plane. I think that they help a lot to increase convective heat exchange between the primary and the air to better offset radiative losses; however, they do almost nothing to dissipate thermal currents in front of the mirror. In my view, Planewave did a VERY poor job of engineering the thermal control components to work as a system. Allowing the focuser to be controlled by the thermal management system is great, but making the focuser a necessary component in the control system was just stupid. I also think that the price of the Delta-T controller is absurd both for what it is and for what it lacks. Even without the focuser, it is useable but it should have been SO much better—and they don’t utter a word about it when you order a system without one of their focusers. The frustrating thing is that PW doesn’t listen to their customers. I had a long discussion with them about the issue of dew control and they privately admitted to me that they are aware of the problems but they continue to do absolutely nothing about it. I love the people at Planewave and I’m extremely impressed by their success but I have seen so many ongoing, unaddressed problems that my next telescope is very unlikely to come from Planewave. John *John, I believe the newer CDK20s now have the 4x perimeter fans as well. They all do except the CDK14 which I was curious to try. PW said it will make no difference on the 14, still didn't my mind at ease. Rouz Like

8.40

#...

· 1 like

John Hayes:

Bill,
I’m not sure that it matters whether the sensor is on the backplane or on the back of the glass. Ideally, what you really want is the temperature of the front surface of the primary and neither sensor gives you that number. Your question is a good one and I don’t have an answer. The ultimate goal is to use the absolute minimum amount of heat that will prevent dew but you still have to add in some margin. The sensor on the rear of the secondary is probably providing the most useful data since it’s directly exposed to the sky—and indeed, it always shows the coldest temperature. You do have the ability to set different target temperatures for the secondary and the primary so there’s room to experiment a little. The bigger problem on my 20” is the location of the fans, which are only on the back plane. I think that they help a lot to increase convective heat exchange between the primary and the air to better offset radiative losses; however, they do almost nothing to dissipate thermal currents in front of the mirror.

In my view, Planewave did a VERY poor job of engineering the thermal control components to work as a system. Allowing the focuser to be controlled by the thermal management system is great, but making the focuser a necessary component in the control system was just stupid. I also think that the price of the Delta-T controller is absurd both for what it is and for what it lacks. Even without the focuser, it is useable but it should have been SO much better—and they don’t utter a word about it when you order a system without one of their focusers. The frustrating thing is that PW doesn’t listen to their customers. I had a long discussion with them about the issue of dew control and they privately admitted to me that they are aware of the problems but they continue to do absolutely nothing about it. I love the people at Planewave and I’m extremely impressed by their success but I have seen so many ongoing, unaddressed problems that my next telescope is very unlikely to come from Planewave.

John

*John,

I believe the newer CDK20s now have the 4x perimeter fans as well.
They all do except the CDK14 which I was curious to try.
PW said it will make no difference on the 14, still didn't my mind at ease.

Rouz

18.93 Ruediger #... · view views · 1 like
Rouz Astro: Ruediger: Hi Rouz, this might work in your case, but I have regularly the situation, that the primary is colder than the backplate. But what is worse, the real ambient temp is below dew point, and the backplate is much higher. The back plate is cooling down much slower, than the air temp drops. When it reaches actual air temp, already the water is poring out of the tube. Also keeping the fans on all the time is only an option when you have no neighbors. In my case it would take very little time that I get a unpleasant visit if I keep them running after 22h. *You are that close to the neighbors! I believe your mount is lot less noisy than my AP mount as well. The fans are surprisingly noisy given the small size, they must be high rpm models, PWM doesn't work but you could swap those fans out for slower more silent ones, even with PWM. I agree its best to have complete control of the system. I do use the backplate temp. to control the primary. Rouz I have discussed replacement of the fans with Bill from PWI support. He was not in favor of. He said they have calculated the air flow not being too high in order to avoid thermal stress on the primary and avoid turbulent cold airflow in front of the primary. Also discussing additional side fans…this was also not recommended. They have sent me the airflow rate for the fans. I will purchase some and hand it over to Baader at the next service for replacing the original ones. Edited ... Like

18.93

#...

· 1 like

Rouz Astro:
Ruediger:

Hi Rouz,

this might work in your case, but I have regularly the situation, that the primary is colder than the backplate. But what is worse, the real ambient temp is below dew point, and the backplate is much higher. The back plate is cooling down much slower, than the air temp drops. When it reaches actual air temp, already the water is poring out of the tube.

Also keeping the fans on all the time is only an option when you have no neighbors. In my case it would take very little time that I get a unpleasant visit if I keep them running after 22h.

*You are that close to the neighbors!
I believe your mount is lot less noisy than my AP mount as well.

The fans are surprisingly noisy given the small size, they must be high rpm models, PWM doesn't work but you could swap those fans out for slower more silent ones, even with PWM.

I agree its best to have complete control of the system. I do use the backplate temp. to control the primary.

Rouz

I have discussed replacement of the fans with Bill from PWI support. He was not in favor of. He said they have calculated the air flow not being too high in order to avoid thermal stress on the primary and avoid turbulent cold airflow in front of the primary.
Also discussing additional side fans…this was also not recommended. They have sent me the airflow rate for the fans. I will purchase some and hand it over to Baader at the next service for replacing the original ones.

Edited ...

8.40 Rouz Astro #... · view views
*I have heard too much cold air on the back can cause astigmatism. But I meant if you are forced to turn the fans off due to the noise, you can replace them will lower speed or PWM fans. They wouldn't create more airflow and will be less noisy, that should be better than no fan at all. I suspect pulling the CDK14 mirror isn't all that difficult. The CDK12 was really bad as there are wires that go to the secondary from the backplate. Hope its solved. Rouz Like

8.40

#...

*I have heard too much cold air on the back can cause astigmatism.

But I meant if you are forced to turn the fans off due to the noise, you can replace them will lower speed or PWM fans. They wouldn't create more airflow and will be less noisy, that should be better than no fan at all.

I suspect pulling the CDK14 mirror isn't all that difficult. The CDK12 was really bad as there are wires that go to the secondary from the backplate.

Hope its solved.
Rouz

18.93 Ruediger #... · view views · 1 like
The CDK 14 is the most complicated to dismantle. 12.5 and 17 is easier. The 14 has a Rouz Astro: *I have heard too much cold air on the back can cause astigmatism. But I meant if you are forced to turn the fans off due to the noise, you can replace them will lower speed or PWM fans. They wouldn't create more airflow and will be less noisy, that should be better than no fan at all. I suspect pulling the CDK14 mirror isn't all that difficult. The CDK12 was really bad as there are wires that go to the secondary from the backplate. Hope its solved. Rouz The CDK 14 is the most complicated to dismantle . The 12.5 and 17+ are easier. They have attached the central light baffle in a different way. At the 14" you cannot unscrew it as the others. It has a horizontal screw securing it right over M1. The baffle had to be replaced and I was strongly advised to have this done at Baader. Also it was warranty. Not a big deal - threw it in the car and 90 minutes drive to Baader. While servicing it they also diagnosed the water marks from poring dew between M1 and back plate. Like

18.93

#...

· 1 like

The CDK 14 is the most complicated to dismantle. 12.5 and 17 is easier. The 14 has a

Rouz Astro:

*I have heard too much cold air on the back can cause astigmatism.

But I meant if you are forced to turn the fans off due to the noise, you can replace them will lower speed or PWM fans. They wouldn't create more airflow and will be less noisy, that should be better than no fan at all.

I suspect pulling the CDK14 mirror isn't all that difficult. The CDK12 was really bad as there are wires that go to the secondary from the backplate.

Hope its solved.
Rouz

The CDK 14 is the most complicated to dismantle

.
The 12.5 and 17+ are easier. They have attached the central light baffle in a different way. At the 14" you cannot unscrew it as the others. It has a horizontal screw securing it right over M1. The baffle had to be replaced and I was strongly advised to have this done at Baader. Also it was warranty.
Not a big deal - threw it in the car and 90 minutes drive to Baader. While servicing it they also diagnosed the water marks from poring dew between M1 and back plate.

11.02 Bill Long - Dark Matters Astrophotography #... · view views · 2 likes
This has been a very educational thread. Thanks to all for the contributions. Like

2.41 Tyrel Smith #... · view views · 4 likes
Following with interest. Lots of great info. My 14” is on the way. This thread is not encouraging. Don’t like that I’m already shopping for workarounds for a new scope in this price range, but going in to this I did have a general idea that the thermal control system was...not great. I just didn’t know the full extent of the not-greatness. It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway? Is it just because the polyimide heater pads are attached to the backplate? Both my RCOS and AGO scopes had the heater thermistors on the edge of the mirror under a piece of cork. The RCOS heater pad was attached directly to the back of the mirror. I guess the idea is to know the temp of the actual thing you are heating, so perhaps that is the reason behind backplate temp? Looking to 3D print a solution to the shroud intrusion problem as well. If I get a good design I’ll share it in separate thread. Good times ahead! Like

2.41

Tyrel Smith

#...

· 4 likes

Following with interest. Lots of great info. My 14” is on the way. This thread is not encouraging. Don’t like that I’m already shopping for workarounds for a new scope in this price range, but going in to this I did have a general idea that the thermal control system was...not great. I just didn’t know the full extent of the not-greatness.

It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway? Is it just because the polyimide heater pads are attached to the backplate? Both my RCOS and AGO scopes had the heater thermistors on the edge of the mirror under a piece of cork. The RCOS heater pad was attached directly to the back of the mirror. I guess the idea is to know the temp of the actual thing you are heating, so perhaps that is the reason behind backplate temp?

Looking to 3D print a solution to the shroud intrusion problem as well. If I get a good design I’ll share it in separate thread.

Good times ahead!

5.01 Yuxuan #... · view views · 1 like
Tyrel Smith: It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway? Tyrel, Not sure swapping wires would work, because then the fan action would then based on the primary backplate instead of the primary. I don't understand why they measure backplate temp either, but I agree with your guess. But the Dew Heater Manager (DHM) app does allow the heater and fan actions to be based on the primary temperature. So if you don't mind the bulk and price, getting EFA+DT+UPB+PWI3+DHM should work. They just need to clean up the mess. Yuxuan Like

5.01

Bill Long - Dark Matters Astrophotography

#...

· 1 like

Tyrel Smith:
It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway?

Tyrel,

Not sure swapping wires would work, because then the fan action would then based on the primary backplate instead of the primary. I don't understand why they measure backplate temp either, but I agree with your guess.

But the Dew Heater Manager (DHM) app does allow the heater and fan actions to be based on the primary temperature. So if you don't mind the bulk and price, getting EFA+DT+UPB+PWI3+DHM should work. They just need to clean up the mess.

Yuxuan

11.02 Bill Long - Dark Matters Astrophotography #... · view views · 2 likes
Yuxuan: Tyrel Smith: It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway? Tyrel, Not sure swapping wires would work, because then the fan action would then based on the primary backplate instead of the primary. I don't understand why they measure backplate temp either, but I agree with your guess. But the Dew Heater Manager (DHM) app does allow the heater and fan actions to be based on the primary temperature. So if you don't mind the bulk and price, getting EFA+DT+UPB+PWI3+DHM should work. They just need to clean up the mess. Yuxuan The EFA without their focuser is a $1200 Gerber Thermometer. No thanks. 🙂 Like

11.02

#...

· 2 likes

Yuxuan:
Tyrel Smith:
It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway?

Tyrel,

Not sure swapping wires would work, because then the fan action would then based on the primary backplate instead of the primary. I don't understand why they measure backplate temp either, but I agree with your guess.

But the Dew Heater Manager (DHM) app does allow the heater and fan actions to be based on the primary temperature. So if you don't mind the bulk and price, getting EFA+DT+UPB+PWI3+DHM should work. They just need to clean up the mess.

Yuxuan

The EFA without their focuser is a $1200 Gerber Thermometer. No thanks. 🙂

8.40 Rouz Astro #... · view views · 2 likes
Tyrel Smith: Following with interest. Lots of great info. My 14” is on the way. This thread is not encouraging. Don’t like that I’m already shopping for workarounds for a new scope in this price range, but going in to this I did have a general idea that the thermal control system was...not great. I just didn’t know the full extent of the not-greatness. It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway? Is it just because the polyimide heater pads are attached to the backplate? Both my RCOS and AGO scopes had the heater thermistors on the edge of the mirror under a piece of cork. The RCOS heater pad was attached directly to the back of the mirror. I guess the idea is to know the temp of the actual thing you are heating, so perhaps that is the reason behind backplate temp? Looking to 3D print a solution to the shroud intrusion problem as well. If I get a good design I’ll share it in separate thread. Good times ahead! * congratulations! The Delta isn't bad, it gets the job done. It would have been nicer to account for RH since its such a simple thing to do. If you aren't using the PW focusers then its not really worth it to get the EFA to power the fan and read the primary temp. I would think its better to heat the backplate and let the radiative heat gently heat the mirror rather than sticking heating elements directly to the mirror as that might cause hotspots? As for the shroud, I've got a carbon solution that I offer for CDK scopes: https://rouzastro.com/product-category/cdk-accessories/ Like

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Tyrel Smith:
Following with interest. Lots of great info. My 14” is on the way. This thread is not encouraging. Don’t like that I’m already shopping for workarounds for a new scope in this price range, but going in to this I did have a general idea that the thermal control system was...not great. I just didn’t know the full extent of the not-greatness.

It sounds like some sensor wires could be swapped to get mirror temp instead of backplate, and the “ambient” probe possibly relocated outside the tube. Probably not easily. What is the idea behind backplate temp anyway? Is it just because the polyimide heater pads are attached to the backplate? Both my RCOS and AGO scopes had the heater thermistors on the edge of the mirror under a piece of cork. The RCOS heater pad was attached directly to the back of the mirror. I guess the idea is to know the temp of the actual thing you are heating, so perhaps that is the reason behind backplate temp?

Looking to 3D print a solution to the shroud intrusion problem as well. If I get a good design I’ll share it in separate thread.

Good times ahead!

*
congratulations!
The Delta isn't bad, it gets the job done. It would have been nicer to account for RH since its such a simple thing to do.
If you aren't using the PW focusers then its not really worth it to get the EFA to power the fan and read the primary temp.

I would think its better to heat the backplate and let the radiative heat gently heat the mirror rather than sticking heating elements directly to the mirror as that might cause hotspots?

As for the shroud, I've got a carbon solution that I offer for CDK scopes:
https://rouzastro.com/product-category/cdk-accessories/

8.40 Rouz Astro #... · view views
Tyrel, Not sure swapping wires would work, because then the fan action would then based on the primary backplate instead of the primary. I don't understand why they measure backplate temp either, but I agree with your guess. But the Dew Heater Manager (DHM) app does allow the heater and fan actions to be based on the primary temperature. So if you don't mind the bulk and price, getting EFA+DT+UPB+PWI3+DHM should work. They just need to clean up the mess. Yuxuan *Yes I tried but you need the EFA as you said. I tried speaking to PW to swap the primary temp. for the backplate but I don't think that is going to happen. Rouz Like

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Tyrel,

Not sure swapping wires would work, because then the fan action would then based on the primary backplate instead of the primary. I don't understand why they measure backplate temp either, but I agree with your guess.

But the Dew Heater Manager (DHM) app does allow the heater and fan actions to be based on the primary temperature. So if you don't mind the bulk and price, getting EFA+DT+UPB+PWI3+DHM should work. They just need to clean up the mess.

Yuxuan

*Yes I tried but you need the EFA as you said.
I tried speaking to PW to swap the primary temp. for the backplate but I don't think that is going to happen.

Rouz

5.61 Bill McLaughlin #... · view views
Tyrel Smith: ooking to 3D print a solution to the shroud intrusion problem as well. If I get a good design I’ll share it in separate thread. I found that the spacers it came with were fine, not sure what the problem is - but then mine is a newer scope (Fall 2022) so maybe the stock carbon supports are better now. Having said that, with the L350 even a small amount of wind is too much so I dumped the shroud entirely and noted an immediate improvement. We are not talking about a lot of wind, less than 5 mph, but with the shroud on I saw tracking go "yellow" pretty often. W/O the shroud that vanished. Fortunately, even that small amount of wind is rare where I am at so combining no shroud with AO and running fans and heaters seems to do the trick. Like

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Bill McLaughlin

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Tyrel Smith:
ooking to 3D print a solution to the shroud intrusion problem as well. If I get a good design I’ll share it in separate thread.

I found that the spacers it came with were fine, not sure what the problem is - but then mine is a newer scope (Fall 2022) so maybe the stock carbon supports are better now.

Having said that, with the L350 even a small amount of wind is too much so I dumped the shroud entirely and noted an immediate improvement.

We are not talking about a lot of wind, less than 5 mph, but with the shroud on I saw tracking go "yellow" pretty often. W/O the shroud that vanished.

Fortunately, even that small amount of wind is rare where I am at so combining no shroud with AO and running fans and heaters seems to do the trick.

2.41 Tyrel Smith #... · view views
Thanks Bill. Having not seen the scope yet I guess I shouldn’t jump to too many conclusions about the shroud. I did not know shroud spacers were included, so perhaps this is a problem that has been solved already. Lot of stray light in my backyard location so I’m stuck with the shroud until I can relocate. Edited ... Like

5.61 Bill McLaughlin #... · view views
Tyrel Smith: I did not know shroud spacers were included, so perhaps this is a problem that has been solved already. As I recall, they are extra cost, so you might want to compare them to the cost of other options like that from Rouz Like

22.61 John Hayes #... · view views · 1 like
I think that there is something that I should mention here. As I said earlier, what you really want it is the temperature of the front surface of the primary mirror. Whether you are measuring the temperature of the back surface of the glass or the back plane doesn't make much of a difference--neither is what you want. There is another consideration that the engineers at Planewave may have run into. When you bond a sensor (or heater) to the rear of the primary mirror, it is possible to get print-through into the optical figure. How much print-through will depend on the thickness of the mirror, the difference in CTE values and where it's attached. It may not be very large but I don't think that very many folks realize how little it takes to induce 1/10 wave (~50 nm) chase in the figure of the mirror. At 50 nm, everything is made of rubber...and you have to be VERY careful about inducing any kind of stress on the glass. Remember that any surface deformation gets doubled in the wavefront so you want to keep any induced figure deformations below +/-1/10 wave. Probably the best way to monitor the front surface of the mirror might be to mount a small coated glass artifact with a temperature sensor bonded to the face off to the side of the primary. That location wlll be slightly warmer than the center of the mirror but it won't be more than maybe 1C off. John Like

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John Hayes

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I think that there is something that I should mention here. As I said earlier, what you really want it is the temperature of the front surface of the primary mirror. Whether you are measuring the temperature of the back surface of the glass or the back plane doesn't make much of a difference--neither is what you want. There is another consideration that the engineers at Planewave may have run into. When you bond a sensor (or heater) to the rear of the primary mirror, it is possible to get print-through into the optical figure. How much print-through will depend on the thickness of the mirror, the difference in CTE values and where it's attached. It may not be very large but I don't think that very many folks realize how little it takes to induce 1/10 wave (~50 nm) chase in the figure of the mirror. At 50 nm, everything is made of rubber...and you have to be VERY careful about inducing any kind of stress on the glass. Remember that any surface deformation gets doubled in the wavefront so you want to keep any induced figure deformations below +/-1/10 wave.

Probably the best way to monitor the front surface of the mirror might be to mount a small coated glass artifact with a temperature sensor bonded to the face off to the side of the primary. That location wlll be slightly warmer than the center of the mirror but it won't be more than maybe 1C off.

John

5.01 Yuxuan #... · view views
The EFA without their focuser is a $1200 Gerber Thermometer. No thanks. 🙂 Rouz Astro: *Yes I tried but you need the EFA as you said. For a 12.5" it's less ridiculous to go with the EFA since the Hedrick focuser is included in the price. Not sure if it's possible or worth it to go without the Hedrick. Like

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The EFA without their focuser is a $1200 Gerber Thermometer. No thanks. 🙂

Rouz Astro:
*Yes I tried but you need the EFA as you said.

For a 12.5" it's less ridiculous to go with the EFA since the Hedrick focuser is included in the price. Not sure if it's possible or worth it to go without the Hedrick.

8.40 Rouz Astro #... · view views
Yuxuan: The EFA without their focuser is a $1200 Gerber Thermometer. No thanks. 🙂 Rouz Astro: Yes I tried but you need the EFA as you said. For a 12.5" it's less ridiculous to go with the EFA since the Hedrick focuser is included in the price. Not sure if it's possible or worth it to go without the Hedrick. I had the Gemini mounted on the CDK12 as well. One thing to note is that CDK12 EFA is not compatible with any other scope, so those that upgrade will need another EFA. some more points to note, besides being smaller (2.75") the CDK12 doesn't have steel tracks to take the load of the bearings. Its that pressure that keeps the focuser stiff. The small bearing run over the aluminum body of the smaller focuser which isn't ideal. I found a bit of flex with the "hand tug" test. If you try to overtighten those load bearings beyond a point they will crack with temperature change (I broke a bunch). The 2x lower bearings are minuscule. Edited ... Like

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Yuxuan:
The EFA without their focuser is a $1200 Gerber Thermometer. No thanks. 🙂

Rouz Astro:
*Yes I tried but you need the EFA as you said.

For a 12.5" it's less ridiculous to go with the EFA since the Hedrick focuser is included in the price. Not sure if it's possible or worth it to go without the Hedrick.

*I had the Gemini mounted on the CDK12 as well.

One thing to note is that CDK12 EFA is not compatible with any other scope, so those that upgrade will need another EFA.

some more points to note, besides being smaller (2.75") the CDK12 doesn't have steel tracks to take the load of the bearings.

Its that pressure that keeps the focuser stiff. The small bearing run over the aluminum body of the smaller focuser which isn't ideal.

I found a bit of flex with the "hand tug" test. If you try to overtighten those load bearings beyond a point they will crack with temperature change (I broke a bunch).
The 2x lower bearings are minuscule.

Edited ...

5.01 Yuxuan #... · view views
Rouz Astro: Yuxuan: The EFA without their focuser is a $1200 Gerber Thermometer. No thanks. 🙂 Rouz Astro: Yes I tried but you need the EFA as you said. For a 12.5" it's less ridiculous to go with the EFA since the Hedrick focuser is included in the price. Not sure if it's possible or worth it to go without the Hedrick. I had the Gemini mounted on the CDK12 as well. One thing to note is that CDK12 EFA is not compatible with any other scope, so those that upgrade will need another EFA. some more points to note, besides being smaller (2.75") the CDK12 doesn't have steel tracks to take the load of the bearings. Its that pressure that keeps the focuser stiff. The small bearing run over the aluminum body of the smaller focuser which isn't ideal. I found a bit of flex with the "hand tug" test. If you try to overtighten those load bearings beyond a point they will crack with temperature change (I broke a bunch). The 2x lower bearings are minuscule. Also, does the 3.5" Hedrick have a motor cover? The exposed motor and wiring on the 2.75" Hedrick is an eyesore on an otherwise beautiful scope. I do have a Optec TCS-3i sitting around that uses Optec-4300 dovetail system that's the same as the Gemini. In your case where did you get the CDK12.5 to Optec-4300 adapter? Like

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