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Encoder performance during recent sub-zero nights


Patrick Spencer
 

Hi Roland, 

Did you have any issues with the encoder performance during any of the recent very cold nights? I know you use the standard temperature encoders, and it seems the recent arctic blast would have provided a good acid test for their limits.

Thanks,

Patrick Spencer


Roland Christen
 

The mounts in my observatory performed normally at -10F. I monitored the encoders during that time and they worked fine. I don't know what the lowest temperature might be where they would stop working. I have two mounts in the observatory and both of them worked normally. No issues with the encoders on either mount.

Rolando



-----Original Message-----
From: Patrick Spencer <patrick.spencer2@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 21, 2021 9:53 am
Subject: [ap-gto] Encoder performance during recent sub-zero nights

Hi Roland, 

Did you have any issues with the encoder performance during any of the recent very cold nights? I know you use the standard temperature encoders, and it seems the recent arctic blast would have provided a good acid test for their limits.

Thanks,

Patrick Spencer

--
Roland Christen
Astro-Physics


Patrick Spencer
 

That’s great to hear, thanks. It sounds like the zero Celsius rating is very conservative.

 

Were both mounts in your observatory Mach 2s, and if so, would there be any reason to expect different performance from the encoders used in the 1100GTO-AE?

 

Patrick Spencer

 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Sunday, February 21, 2021 10:29 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Encoder performance during recent sub-zero nights

 

The mounts in my observatory performed normally at -10F. I monitored the encoders during that time and they worked fine. I don't know what the lowest temperature might be where they would stop working. I have two mounts in the observatory and both of them worked normally. No issues with the encoders on either mount.

 

Rolando

 

 

 

-----Original Message-----
From: Patrick Spencer <patrick.spencer2@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 21, 2021 9:53 am
Subject: [ap-gto] Encoder performance during recent sub-zero nights

Hi Roland, 

Did you have any issues with the encoder performance during any of the recent very cold nights? I know you use the standard temperature encoders, and it seems the recent arctic blast would have provided a good acid test for their limits.

Thanks,

Patrick Spencer


--
Roland Christen
Astro-Physics


Roland Christen
 

One is a Mach2, the other is a 1600 mount, which has the same encoders as the 1100. The readheads are all the same on all these mounts. The readheads have a laser diode that is used to read the scribe marks on the stainless steel ring. I'm guessing that at some low temperature the laser stops producing light and the readhead can't read the engravings. When that happens the signal light on the readhead turns red which indicates a fault.

For the 1100 and 1600 mounts, when this happens the mounts revert back to non-encoder operation. The mounts will operate normally like any non-encoder mount because the servo motors have their own shaft encoders that are used for tracking and positioning. You will lose the perfect tracking accuracy of the two axes along with the instant reversal capability in the Dec axis.

For the Mach2, with the present CP5 software a loss of encoder function will prevent the mount from being Homed and prevent it from being parked at the 5 park positions. The mount will still track and guide (at reduced accuracy) and can be slewed to objects and moved via the buttons, again at reduced accuracies. The home and park functions will fail since they are set points on the encoder rings. I am testing new CP5 software that will allow it to be parked at or very near the 5 park positions. Also the CP5 will indicate encoder non-operation with the indicator on the CP5 turning to amber. Basically the Mach2 will operate open loop as a non-encoder mount. We will release that software when it is fully tested.

Roland



-----Original Message-----
From: Patrick Spencer <patrick.spencer2@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 21, 2021 11:46 am
Subject: Re: [ap-gto] Encoder performance during recent sub-zero nights

That’s great to hear, thanks. It sounds like the zero Celsius rating is very conservative.
 
Were both mounts in your observatory Mach 2s, and if so, would there be any reason to expect different performance from the encoders used in the 1100GTO-AE?
 
Patrick Spencer
 
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Sunday, February 21, 2021 10:29 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Encoder performance during recent sub-zero nights
 
The mounts in my observatory performed normally at -10F. I monitored the encoders during that time and they worked fine. I don't know what the lowest temperature might be where they would stop working. I have two mounts in the observatory and both of them worked normally. No issues with the encoders on either mount.
 
Rolando
 
 
 
-----Original Message-----
From: Patrick Spencer <patrick.spencer2@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 21, 2021 9:53 am
Subject: [ap-gto] Encoder performance during recent sub-zero nights
Hi Roland, 

Did you have any issues with the encoder performance during any of the recent very cold nights? I know you use the standard temperature encoders, and it seems the recent arctic blast would have provided a good acid test for their limits.

Thanks,

Patrick Spencer

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Jeffrey Wolff
 

I have the 1100 with extended range on order. Looks like i probably would be fine with the standard range but didn't want to feel limited so I chose the extended range.  42 degrees below specs is pretty impressive. I was more worried about the -4 F storage limit.

At the price of the mount with encoders I didn't want to take the risk that some future location would have too low of temperatures to use the mount with encoders. The price difference isn't that great so I don't mind paying the extra.


Roland Christen
 

I have had the 1600 mount in my observatory for a decade. It has standard encoders that have seen at least 10 Midwest winters, so the -4F storage spec from Renishaw is probably very conservative.

Rolando

-----Original Message-----
From: Jeffrey Wolff <jmw2800@...>
To: main@ap-gto.groups.io
Sent: Sun, Feb 21, 2021 12:37 pm
Subject: Re: [ap-gto] Encoder performance during recent sub-zero nights

I have the 1100 with extended range on order. Looks like i probably would be fine with the standard range but didn't want to feel limited so I chose the extended range.  42 degrees below specs is pretty impressive. I was more worried about the -4 F storage limit.

At the price of the mount with encoders I didn't want to take the risk that some future location would have too low of temperatures to use the mount with encoders. The price difference isn't that great so I don't mind paying the extra.

--
Roland Christen
Astro-Physics


Jeffrey Wolff
 

Well now I am doubting my need for absolute encoders. I live in Reno and probably will not be moving to a colder location. I use the mount quite a bit in the +10 - 32 F and warmer range so that is why I chose the absolute. It as seldom actually been below zero in the 35 years I have been here. Since the -4 F storage limit doesn't seem to be a problem, I don't need to worry about using the absolute version. 

I put down my deposit on Friday. I will call on Monday and see if I can change to the standard range encoders.


Joe Zeglinski
 

Jeff,
 
    Have you taken into account “wind gust temperatures”, on the worst winter days, where you plan on moving to a colder location?
Perhaps, the mount & encoders will be at reasonable temperatures – inside an observatory, as Rolando’s test systems are housed. Otherwise, check the Weather Bureau history log for the past year(s). If the two kinds of encoders are equally available, i.e. within a reasonable time frame, it might not be that much of a bottom line, ultimate savings, in the long run.
 
Joe Z
 


Jeffrey Wolff
 

Most years it doesn't go below 0 F in Reno. It has reached -17 F back in 1919. The average winter low Reno is 23 degrees F on the coldest months.

If I moved to a place above 7000 feet then I might see temperatures down -15 F or colder. The snow might be so deep there I wouldn't be able to keep my observatory clear of snow. If I moved it may be a bit further south. Haven't lived north of I80 in about 40 years.

I was born in Michigan and remember -28F on Christmas day when I was in my 20s.