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Posts Made By: David Simper

March 28, 2006 03:32 AM Forum: Ham and Shortwave Radio

Communication in desert

Posted By David Simper
I was on a 2,800 mi trip recently around the SW National Parks. I learned how my mobile phone is limited as a communication mean as it was out of signal most of the time.
If I would undertake a similar trip in the future with the kids, I definitely would like have the way to call for help if in trouble. What shall I look for on the market ?

March 29, 2006 04:40 PM Forum: Equipment Talk

Do you need an interferogram purchasing a star dia

Posted By David Simper
I just have heard to my dismay this morning from a premier diagonal glass optical manufacturer how my (originally very expensive) 2" enhanced silver mirror I sent for recoating (it developed areas of marring) did on an interferometric test. So called 1/20th mirror had only the sweet spot of 1/4th wave, the rest was worse. He suggested to dump it. I might look for a glass only replacement...I will send an anonymized copy of the interferogram to the original manufacturer for his comments but do not expect much based on previous contacts with him.

This confirms the results Vic Maris obtained when he measured interferometrically comparable market offerings during development of his SV diagonal.
There are now many options on the star diagonal market, more than 1-2 years ago. But nobody to my knowledge will guarantee you the stated optical performance with an interferogram.

David

April 4, 2006 12:30 AM Forum: Equipment Talk

Comments on diagonal Zygo

Posted By David Simper
I received the Zygo test of the diagonal mirror which was rated at 1/20 th wave at purchase. Can the optical pundits comment what they see ?
The edge defects (left) are from the silver layer corrosion.

Edit add-on: my take is that there is a middle zone ca. 1" long which falls into the 1/20th wave (0.05) when I look on the surface profile. So I would say not so super bad as I understood initially when one considers that just center of the mirror would be used (in contrary to a diagonal in a reflector).
Still, with $50 asked for recoating, I can better go for a new $58 dielectric 1/10 wave glass from WO...

April 18, 2006 03:05 AM Forum: Reflectors

Re: Mirror help please...

Posted By David Simper
Jim,

hopefully you will get some money back from Uncle Sam, one thing to consider is, how much time/effort/$$$ you will spend on shipping, testing, coating, building new tube etc. instead of observing.

Check:
http://www.starmastertelescopes.com/html/10inch_hybrid.htm

and consider one idea - even if you find that the hobby is not for you and on the sale of the SM10 you would loose let's say $800, (maybe the same amount it would cost you to bring your current scope in shape), you would still have the joy of using a perfect scope.
Just ask Floyd what he thinks about the mirror ;-)

May 22, 2006 06:27 AM Forum: Star Parties

GCSP North Rim Cabins available

Posted By David Simper
I will be cancelling my GCSP reservation with Xanterra of 2 Frontier Cabins- they sleep three people maximum with one double bed and one single bed. They also have 3/4 bath (shower only). Rollaways are not permitted and that is (plus ca. $95/night price) the reason it would not work for us (5 kids and parents).
If you would be interested to take over the reservation (nothing is available there for June), let me know soon.
I will try to come up with some alternative for us either on North or South Rim.

David

June 15, 2006 05:50 AM Forum: Telescope Making

Lead plate sources for counterweigh

Posted By David Simper
My 16" Dob is not balanced well enough binoviewing with current 9 lb of lead in the form of ca. 2.5x2.5" squares 0.5" thick which are attached by industrial Velcro pads (glue fell anyway off in hot FL weather at WSP) to the bottom of the mirror box.
I am looking for lead source in plate form, where...?

July 4, 2006 04:57 AM Forum: Reflectors

Mirror transport

Posted By David Simper
I was recently on a week trip around AZ/UT with my 16" reflector.
I still keep the 3 layer hard foam sandwich and (optical?)
paper cover that the mirror was sent in. With daily changes of
camping place, it became apparent that for the field trip, this
storage is not optimal. I was concerned about hard dust coming between
the mirror face and the paper (we awakened with red sand covering the
sleeping bags after a windy night in Monument Valley). I kept the box
with the mirror on its side thinking that the foam gives better
cushioning to the road bumps in this position. My scope has a very
open mirror box and with its mirror support (whiffle tree and cable)
it is not deemed to keep the mirror inside during longer transport.

I am thinking about some wooden/plastic tight box for the mirror
storage and transport but have not a clear idea about the inside arrangement.
How are other people solving this problem ?

Thank you,

David

August 4, 2006 12:02 AM Forum: Equipment Talk

Encoders-to-PDA interface

Posted By David Simper
What do I need to connect output from encoders into the serial adapter on my Dell Axim PDA which has SKY loaded ?

August 5, 2006 04:33 AM Forum: Telescope Making

New Dob DSC add-on option

Posted By David Simper
I am wondering whether by release of

http://www.telescope.com/shopping/product/detailmain.jsp?itemID=91937

there would be an opportunity to use this kit to have digital setting circles on a Dob for less than a half the usual price ?

Those round encoders should be easy to adapt on the base and alt ring. (Previous Dob kits contained only one encoder)

On a related topic, see:
http://www.upl.cs.wisc.edu/~de-smet/intelliscope.html

http://www.upl.cs.wisc.edu/~de-smet/Malte.html

August 19, 2006 07:23 AM Forum: Reflectors

Mirror clips ?

Posted By David Simper
Mirror clips have been in my understanding detrimental for a perfect picture by increasing diffraction. On the ad for a telescope from a famous maker on AM, I noted hefty clips on the picture. Also, CPT's aluminium mirror cell has clips.
What is your take on clips ?
I am mentally preparing list of features for my future 12.5" thin (1") mirror reflector.

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