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Few questions regarding this 150mm E. Popp Maksutov

Beginner Classic Maksutov
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#1 jroo

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Posted 08 October 2021 - 07:00 PM

Hey there all , Brand new member here and astronomy novice.  I recently came into this vintage 1969 150mm Eugen Popp Maksutov. As for the scope I have not plugged it in yet as it has euro plug and i am in the usa. I was going to get a voltage converter but not sure if it would work... Would that keep proper time for the mechanism to track properly or would i need a regulator of some sort?  It came with 4 Spectros eyepieces which are spotless except for a little dust. I would really love to replace the focuser with a newer smooth two stage because this one is pretty short.  My other scope is a 10" Apertura Dob that i have had for about a year and a half. With the Mak I was able to look at some tree tops that were far enough away to see clearly and focused with the F40 eyepiece and i can tell that the mirror could use a little dusting but not bad. Opening the very tight front cover it smelled like my grandmas closet (im in my 50's) but the secondary looks just like new to me. The stand its on weighs about 40-50 lbs. Overall i am pretty excited that i get to own this beauty but if the tracking works i will be over the moon. 

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Edited by jroo, 08 October 2021 - 07:02 PM.

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#2 ccwemyss

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Posted 08 October 2021 - 07:47 PM

Wow, these are popping up like crazy - second one in a week to show up.

 

https://www.cloudyni...-buying-advice/

 

Chip W.


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#3 fftulip

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Posted 08 October 2021 - 07:50 PM

Nice looking scope.  If the drive is European chances are it runs off 50 Hertz AC so wouldn't track properly if you supplied it with 60 Hertz from USA power.  I have heard of power converters that also change the frequency but another option is to open it up and see what kind of motor it uses.  Probably an AC synchronous motor so you may be able to substitute one so that it has the proper frequency/speed.


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#4 jroo

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Posted 08 October 2021 - 08:00 PM

Nice looking scope.  If the drive is European chances are it runs off 50 Hertz AC so wouldn't track properly if you supplied it with 60 Hertz from USA power.  I have heard of power converters that also change the frequency but another option is to open it up and see what kind of motor it uses.  Probably an AC synchronous motor so you may be able to substitute one so that it has the proper frequency/speed.

 

thats kind of what i thought may happen. Gonna carefully open up the box this weekend and see whats doin. I also saw a post somewhere and a guy installed a regulator into the base of a C8 i think it was but if it replaceable that may be the route to take. 



#5 ccwemyss

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Posted 08 October 2021 - 08:03 PM

There are old-school digital drive correctors that let you dial in a frequency, usually to correct for solar or lunar tracking, but the range would allow for 50Hz output (at least on the Kencor that I have). 

 

Chip W. 


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#6 jroo

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Posted 08 October 2021 - 08:14 PM

Wow, these are popping up like crazy - second one in a week to show up.

 

https://www.cloudyni...-buying-advice/

 

Chip W.

The folks that bought them new are kicking the bucket and their kids are liquidating their inheritance seems like. Im in the Art and Antique auction business and that is how i came across this one. I have the original receipt from E. Popp Tele-Optik  as well as some other paperwork. Not much info out there that i have found for such a well made scope. Cheers!

 

EDIT: I just noticed that i also have E. Popp's signature on the receipt. 


Edited by jroo, 08 October 2021 - 08:26 PM.

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#7 luxo II

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Posted 08 October 2021 - 09:14 PM

Regarding the drive you should find a synchronous motor with gearbox. it’s usually possible to find another to replace it (you’ll have to do the wiring).

 

There is another alternative, however. Most small synchronous motors were made to a standard “form factor” and it is possible to find a stepping motor and gearbox combination that would replace it nicely.

 

To do this:

 

1. You need to know the gear reduction of the RA worm (equals the number of teeth if the worm is a single-start thread).

 

2. Assume a typical stepping rate for the motor, say 50 Hz, and assume the motor will have 200 steps/rev.

 

3. You will need a stepping motor driver such as the ones from Pololu.com. The nominal tracking rate can be produced using a CMOS timer IC (7555) with a handful of components - you don’t need a microprocessor.

 

4. From the stepping rate and the worm reduction, calculate the gearbox reduction required, and

 

5. Choose a gearbox and stepper to match the form factor of the original motor. Chances are you won’t find a gearbox with the exact ratio you want; choose one close then recalculate the required step rate to match.

 

6. For the timer circuit, you can use a typical “RC” timer circuit with the  7555; include a potentiometer so that you can adjust the motor speed say +/- 20%.

 

This is well within the realm of DIY and will run nicely off 6 - 12VDC. 


Edited by luxo II, 08 October 2021 - 09:18 PM.

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#8 jroo

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Posted 15 October 2021 - 07:05 PM

Regarding the drive you should find a synchronous motor with gearbox. it’s usually possible to find another to replace it (you’ll have to do the wiring).

 

There is another alternative, however. Most small synchronous motors were made to a standard “form factor” and it is possible to find a stepping motor and gearbox combination that would replace it nicely.

 

To do this:

 

1. You need to know the gear reduction of the RA worm (equals the number of teeth if the worm is a single-start thread).

 

2. Assume a typical stepping rate for the motor, say 50 Hz, and assume the motor will have 200 steps/rev.

 

3. You will need a stepping motor driver such as the ones from Pololu.com. The nominal tracking rate can be produced using a CMOS timer IC (7555) with a handful of components - you don’t need a microprocessor.

 

4. From the stepping rate and the worm reduction, calculate the gearbox reduction required, and

 

5. Choose a gearbox and stepper to match the form factor of the original motor. Chances are you won’t find a gearbox with the exact ratio you want; choose one close then recalculate the required step rate to match.

 

6. For the timer circuit, you can use a typical “RC” timer circuit with the  7555; include a potentiometer so that you can adjust the motor speed say +/- 20%.

 

This is well within the realm of DIY and will run nicely off 6 - 12VD

Thank you for the detailed instructions and the links as well. I will post when i get it all dialed in. Cheers!



#9 dave brock

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Posted 16 October 2021 - 08:18 PM

I'd first just try it with an adapter plug. The fact it's already in your country suggests to me whoever owned it

may have had it working properly already.


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#10 jroo

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Posted 16 October 2021 - 09:05 PM

I'd first just try it with an adapter plug. The fact it's already in your country suggests to me whoever owned it

may have had it working properly already.

good point. I have not altered it yet so will give that a go first.




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