Re: ATM Beyond the fan

[mohib_ebrahim.smz@attglobal.net]

Hi:

This is exactly what Yuri at TEC is planning to do. Here's a few recent
posts of his on this very topic from a thread on the yahoo groups makscopes
forum, in case you're not able to get in:

-------------- START OF POSTS --------------

Hi Steve and others Mak lovers,

Yes we just add a couple New things to our web :
APO140 and the 12" MAK, as well we removed all MNs.Here is some extra
information about MC300/15.
Weight estimated appr. 60lb
Tube length from meniscus cell end to the rear handle - 38"
TA diameter - 14.33"
Focusing principle similar to all other our MAKs, but optional focusing
with stepper motor via hand unit manualy or with a computer.
The main difference of MC300 is an optional cooling system that will cool
the TA to the same T as outside air and than will follow the outside T.
When all part of telescope incl. air inside have same T (as outside T) -
the tube carrents should be gone too.
More details will be available after testing on 12" under real sky, last
year test on C14" was successfull. The digital controller was designed by
two talanted engineers. Controller also takes care about due heater (if
needed) and stepper drive.
CO <= 25% baffling included, no hiddedn obstruction.
1/8 PV at focus.
Beral coating on mirrors, BBArR on meniscus.
First run of six scopes is sold. (#6 last week)
Regards,
Yuri



> Has anyone used Peltier (spelling?) coolers for their Mak? It seems that
> people are not too keen on pumping air through the system, but how about
> dropping the temperature of the system with an electronic cooler. This
> would probably work even better with an internal recirculating fan, and
with
> the appropriate electronics, it should be possible to match
> internal/external temperatures of the system.

It is my understanding that the TEC thermoelectric Mak coolers employ this
very same principles.
Thanks,
Vahe



Hi Bill,
You are corect , with Palermiti cooler - it does not work, with Peltier -
it does.
[snip]
Regards,
Yuri

-------------- END OF POSTS --------------

Of course one could try this:

>>> This dry Nitrogen or CDA (Clean Dry Air) purge is something I've been
>>> wondering about too. In fact at work today (semiconductor fab), I
>>> just priced a system for this purpose (don't tell my boss!) for
>>> $190.00. If the bottle was at outside ambient temp or the bottle's
>>> outlet flow went through a heat exchanger to cool it... hmmmm... of
>>> course just the expanding gas will cool naturally... fast cooling, no
>>> contaminants, dewpoint of gas less than minus 40 deg C. If N2 is
>>> used, no oxidation too.
>>>
>>> Can this be done? Has this been done? Am I nuts?
>>>
.>>> Randy Johnson
>>
>> I do not know about nuts, but it these was done by one of our customer.
I will
>> try to find pictures of equipment and put them in the file section on
Tuesday.
>> Yuri
>>
>>I just uploaded three pictures in the File section / 0cooling, that shows
 king of
>>extreme way to cool the Mak (I would not to do this to everyone , since
balle
>>could be damaging).
>>Here is a comment of this cooling inventor:
>
>Dear Yuri,
>I have attached a photo of the 10" f20 with the air tank used to cool the
>internals of the OTA. It works like a champ. The scope is ready for
viewing
>after about 10 minutes of cold air injection and circulation, even when
hot like
>after being driven in the back of the car for a couple of hours. You might
 like
>to think about making a permanent injection port for this purpose.
>Take care,
>John Curry



The pictures are at this URL
http://groups.yahoo.com/group/MakScopes/files/0cooling/

Mohib



On 02/21/2002 08:15:38 AM Chuck Hards wrote:

>Has anyone tried attaching a Peltier heat-pump to the back of a mirror, or
>an array of them?  The heat produced by the "hot" side could be pulled
away
>by a rear-mounted fan blowing backwards, straight out of the tube.  The
>"cold" side can get SO cold that it may be able to cool a mirror much
faster
>than a fan alone.  It doesn't address immediate boundary-layer problems on
>the mirror's face, a small fan may still be needed if you're in a hurry,
but
>it may shorten appreciably the total cool-down time required.  I can tell
by
>recent posts that some people still aren't convinced that active cooling
is
>good insurance.
>
>You know, you could even use one in an opposite configuration to heat an
>eyepiece, kind of a high-tech "eyepiece cozy".
>(Sticking your tongue to the flagpole in winter is nothing compared to
>getting your eyeball stuck on a Plossl......just eliminating the "brain
>freeze" is a step in the right direction!)
>
>Just an idea, perhaps more practical than a "levitating secondary"!
>
>C'mon, Richard, let's hear it.  Dig into this one!
>
>Chuck
>
>