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Posts Made By: David Simons

February 1, 2004 12:00 PM Forum: Equipment Talk

Voltage and battery question

Posted By David Simons

Hi Paul,

I just checked the LX200 manual, it says the average current draw is about 1 amp with much higher draw during slewing. When you say the 6 volt is rated at 4 amps, I'm guessing you read 4 ampere/hour, which would give around 4 hours at 1 amp. The 12 volt then giving 12 hours. But since the weakest link is the 4 amp, that is your limit. I can't comment on exploding batteries, but I know the parts inside the LX200 get hot if the voltage gets a lttle low (ie. don't run your scope with 12V alone), which can burn out the internal circuit board.

Bottom line, 4 hours seems a little short, but if you just do a quick observing session, probably OK. Factor in cold conditions, and that battery will go down fast, possibly leaving the heavy duty 12V all by itself, either causing the hot circuit board, or as others suggest, heating up/damaging the 6 volt also!

A somewhat innefficient, but maybe cheap way to go is use your big 12 volt, run it into a 120VAC converter (these are cheap these days), then use your standard equipment AC to 18V supply.

David Simons

February 11, 2004 10:20 PM Forum: Beginning Astronomy?

10

Posted By David Simons

Hi Kent,

I just saw a really great intro to astronomy book.

"THE MONTHLY SKY GUIDE" by Ian Ridpath. Wil Tiron.

I thought it gave some nice background information on the constellations, where they are, and what to see in them. I wish I had this book when I was starting out. It has large pages, with enough detail to make it interesting, but not appear overwhelming. The star maps are great and it has some good closeup charts for when there are many interesting things in an area.

David Simons

February 13, 2004 09:21 PM Forum: Equipment Talk

What is the ultimate personal scope?

Posted By David Simons

Inge,

Speaking of "Bells and whishtles" I'd wish for 20-20 vision, OK maybe 20-15, and dark adaption like Leslie Peltier.

After that, any scope would appear to work much better !

David Simons

February 22, 2004 09:41 PM Forum: Equipment Talk

LX200 GPS vs Classic GOTO?

Posted By David Simons

Hi Anthony,

I have the old LX200 12" and as you say, it's dead on. Also the old scopes are really easy to setup and the clutch works great.

I also have the 10" GPS and had big plans of tracking asteroids and minor planets, but that has not happened yet. I find the GPS searching and leveling are very time consuming compared to the old LX200. If you are used to the old system, the new one will seem very awkward, and you find yourself waiting around for the intial alignment. If you have never used a scope before, then the GPS takes care of everything for you, it is just slow until you get everything initially lined up. After that everything is very similar including pointing accuracy. I think it is even possible to bypass the GPS alignment and do a single star alignment like the original LX. The handling of the scopes is better on the older ones. I find it easier to handle the old 12" than the new 10". The placement of the handles is very awkward.

Also the cord wrap issues on the new ones are something to be aware of. My scope came with an internal connector broken, a common problem with the early GPS scopes, and easy for me to fix, but some would have returned theirs.

I would look at getting a larger older style LX200 since the prices seem to have come way down, and the scopes appear to be a bit more rugged. Although the 12" GPS scope optics seem to be a sweet spot for Meade right now. The ones I have looked through have been very sharp.

Also Meade is selling the OTA's at very good prices now.

Enough rambling !

Good luck !

David Simons

March 1, 2004 09:21 PM Forum: Equipment Talk

Any electrical experts out there?

Posted By David Simons

Hi Vincent,

Rough guess, I would say each system is around 75%, so a full trip 0.75 x 0.75 ~ 0.5, so ~50% (56?) total efficiency.

But trying it out should be fairly quick !

To actually measure the eff. would not be too bad, but you would need a clamp-on current probe to measure the AC current out of the inverter, and a DC current meter going into the inverter. If you have this equipment we can go into more detail.

Your inverter may actually spec. out the eff. in the manual somewhere. The charger manual would likely not give this kind of info.

ex-spurt

David Simons

March 2, 2004 12:29 PM Forum: Equipment Talk

Astrophysics Traveller

Posted By David Simons

Hi Joe,

AP actually makes an accessory dovetail SB0800 that screws to the top of the rings. ~$25 if I recall. It has extra holes, and other finder scopes can mount to it.

David

March 3, 2004 11:03 PM Forum: Equipment Talk

A good mount for about 28lbs of weight?

Posted By David Simons

Ashton,

Maybe a used AP900QMD ? A 900 class mount is about right, since for CCD, overmounting is normal.

These were the precursers to the GTO version. About half the price also !

A quick ad on AM will probably turn up a few.

Takahashi mounts are good. But others will have to tell you which would be best. Ron Wodowski's CCD book goes into this in some detail.

hmm, this looks about right:
http://www.astromart.com/viewad.asp?cid=254113

A G11 would be great for visual, and maybe CCD, but the drive gearing can be rough on some units. It may be possible to upgrade the gears ?

Congrats on your 155 !!

David Simons

March 8, 2004 05:55 PM Forum: Deep Sky Observing

Recommend a galaxy to look at?

Posted By David Simons

Hi Van,

I'm going to reply on the Beginners Forum since I think there are a few other folks just starting out that would like to see this thread as well.

David Simons

March 9, 2004 11:43 PM Forum: Equipment Talk

Orion 120ST review

Posted By David Simons

Brian,

I did a quick yahoo search on ST120 and CCD and came up with this link:

http://www.mwetech.com/markestes/m13av120.gif

http://www.mwetech.com/markestes/deepspace.html

scroll down a little bit for the ST120 pictures

Looks like he has done a decent job.

Although I have a ST120 and an ST-8i, I have not tried the combo. I would think you would want to shoot with a yellow green filter in place, as the best correction for the lens is probably in this region.

Most folks that use a refractor for imaging tend to use the higher quality lenses. Also consider the Orion ED80, or a Televue Pronto or Ranger, as they will give a very snappy focus.

You might want to re-post this Q: in the CCD forum, as there are very knowledgable folks there.

David Simons

March 10, 2004 02:40 PM Forum: Equipment Talk

SP-C102F as in Fluorite d=102 f=900

Posted By David Simons

Hi Duane,

There have been a number of these advertised on AM the last year, prices seem to be getting a little low as Takahashi has a sale on their 4" scope, also the economy is not helping either. However as your scope is essentially new, it should have somewhat of a premium. If you cannot find the previous scopes for sale on Astromart, post here again.

David Simons

PS I have one of these, and they are wonderful scopes !!