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Hi Gregory,
Thanks for replying. The previous owner of the mount is of the opinion that
the polar finder will get me close enough to use the DSCs with only a 1-star
alignment. Do you agree?

I'm almost certainly going to buy this mount. It is being offered to me at
about 1/2 the price for a new mount, DSCs and other accessories and as far
as I can determine, it is in pretty much new condition. Are there other
accessories I should consider getting? I'm certain I'm going to want the
side-by-side saddle plate. Are the RA/Dec replacement clutch knobs useful?
The replacement knobs for the screws that attach the mount to the tripod
look useful. Is a similar replacement knob available for the screw that
locks down the latitude adjustment? I hate fumbling with allen wrenches in
the dark.

There is no grease on the polar scope or where it mounts. I have the polar
scope, a small, white plastic washer that fits against a flange on the
widest part of the polar scope (not sure which side of the flange it goes
on, closest to the objective or the eyepiece?) and the retaining ring that
screws onto the RA housing to secure the polar scope. If I tighten the
retaining ring completely, the polar scope won't move (in fact, attempting
to move it only unscrews the retaining ring). Should there be a second
washer or something to allow the polar scope to float against the retaining
ring and the RA housing?

Is a dust cover of some kind available to protect the polar scope if it is
left in place all the time and to close the end of the RA housing when the
polar scope is not in place?

Here's what the manual says about setting the scope to +90 degrees when
doing a 2-star alignment with a GEM:

Losmandy DSC Manual, Section 5.3, Page 6
"When you are prompted for 1 or 2-star alignment, select 2-star. You will
be prompted to set the scope to +90 degrees. This means relative to the
scope, not the sky. For instance, if the scope is on a fork mount, it
should be positioned parallel to the form arms. For a German Eq, the scope
should be parallel the polar shaft.

For fork mounts, this positioning is not very critical (within a degree or
so is fine). If the mount is a German Eq, you must set this position with
some accuracy. See appendix (A) which describes a method for determining
the +90 degree position for German equatorial."

Appendix A describes a method for determining the +90 degree point by
sighting on Polaris and rotating the scope from one side of the mount to the
other -- centering Polaris using the alt-az controls on one side and shims
on the other (not something I particularly want to do every time I set the
scope up).

There is something else I noticed last night. The manual, in the section on
calibrating the mechanical declination setting circle, a set screw to lock
down the dec circle is mentioned. The manual also says the screw should be
between 0 and 10 degrees declination. I can't find that screw anywhere. Is
it so small that it is hard to see or is my mount an older model that is
missing something?

Thanks,
================================================
Ray Porter
Applications Analyst Programmer
Administrative Information Services, UNC-CH
Phone: 966-5878
email: ray_porter@...
dragon@...
Home Page:

"Meddle not in the affairs of dragons,
for thou art crunchy and taste good with ketchup."

Ray,

You should be able to turn the polar finder without releasing the
locking ring. The polar finder may be stuck from old grease??

You can't use the DSC's in alt-az mode on a GEM. You CAN use them
without polar aligning.

You do need to do two star alignments initially. Generally the first
alignment may be off by quite a bit, but the second if done well with
bring everything into alignment. After two stars, I am still off a bit,
so I use "guide" to M13 which is easily picked up in my finderscope as a
third and final alignment target.
If you leave the DSC's powered up all of the time via AC then you
obviously would not need to worry about aligning. Just occasionally
update by aligning on any target.

The polar alignment scope will give you a very close polar alignment
though, enough to test CCD's for focus, study clusters or nebula, watch
for comet or neo movements, etc.. Take your time. Every effort here only
pays off in the long runs.

I am not sure of the +90 question. There is an initial balancing of the
GEM and initializing to 0 DEC (for my DSC's) which is a process I have
to do each time I set up. After a few times, it requires a little
effort. The LX200 series does make this process a lot easier, granted.

Your polar finder illuminator sounds like an older model, mine is from
JMI and has small actuator button with the built in battery compartment.
About an inch square for the whole thing. You may be able to change to
newer switch if they are sold independant of the polar finder. Give JMI
a call.

Hope this helps.

Take care,
Gregory david Stempel
FIREFRAME

George,

Define your purposes first. Are just into the visual targeting or do you
plan anything like imaging, photometry or astrometry?

GEM's make excellent platforms for the above but is unecessary for
casual or general purpose viewing. Forks require additional wedges or
other accessories to accomplish most of the above.

GEM's typically are more stable than forks. Can be a lot easier to polar
align and give you views of virtally any area of the sky. Forks can hit
their mountings and make it difficult to view your zenith.

Accuracy of pointing is generally the same with either. This is more
dependant on encoder resolution and accuracy of alignments.

Get a GEM. I would not advise though, putting a 9.25 on a GM-8, unless
you do not plan on adding too many accessories. Wieght limit for the GM8
is 30 lbs or so.

Take care,
Gregory david Stempel
FIREFRAME

I can comment on #4, as I have a C9.25 that I use on both a GM8 and a GM100
(predecessor to the G11). IMO, the GM8 is enough mount for visual use but
not for photography or imaging through the scope.

There was a discussion recently (within the past three weeks) about GEM vs.
fork. You might want to check the archives.

Paul Sterngold

--- George Smith <gsmith4789@...> wrote:

I am going to purchase an SCT but am undecided on a GEM or a fork
mount. Under consideration are: C8 Deluxe, LX 200, U2K and C 9.25 on
a GM 8. Any information you could offer on the following would be
appreciated:
1) Advantages / disadvantages of a SCT-GM8 combination compared to a
fork mounted SCT.
2) Portability of GM 8 compared to forks.
3) Experience of anyone using a C 9.25 with a GM 8.
4) Is a GM 8 enough mount for the C 9.25 or is a G 11 more
appropriate.

This will be a significant investment for me so any information you
can provide would be appreciated.

George Smith

__________________________________________________
Do You Yahoo!?
Yahoo! Mail - Free email you can access from anywhere!

I am going to purchase an SCT but am undecided on a GEM or a fork
mount. Under consideration are: C8 Deluxe, LX 200, U2K and C 9.25 on
a GM 8. Any information you could offer on the following would be
appreciated:
1) Advantages / disadvantages of a SCT-GM8 combination compared to a
fork mounted SCT.
2) Portability of GM 8 compared to forks.
3) Experience of anyone using a C 9.25 with a GM 8.
4) Is a GM 8 enough mount for the C 9.25 or is a G 11 more
appropriate.

This will be a significant investment for me so any information you
can provide would be appreciated.

George Smith

Thanks Rockett and Paul for the feedback. I was afraid there was a
problem and you guys confirmed it. The cables are all plugged in
correctly (that was the first thing I checked). I called Pocono West
where I had purchased it and talked to Glenn. He then had me call
Scott Losmandy. Mr. Losmandy confirmed that something was wrong. I
will check the wiring in the back of the hand controller when I get
home today and if I can't solve the problem, I will have to send the
control box and the hand controller back to Losmandy.. Mr. Losmandy
said he'd never heard of that problem before though. Sort of a
bummer since its just one day old :(

Tony

hermperez@... wrote:

Rockett, I'm sorry but I cant explain my argument better, lead acid batteries
have a finite number of times that they can be discharged to zero,

All batteries do, not just lead acid.

The cycling does not waist a discharge since the batteries are no good
to me on that first charge/discharge cycle because they will die on me
1/2 way through the night.

also they
don't suffer from a "memory effect". I really don't know why you are noticing an
improvement but if it works for you...

I didn't say anything about them having "memory effect" and my description of
the problem doesn't fit the definition of the memory effect. That is caused by charging
nicads over and over without fully discharging them. I am familiar with this
phenomena because I also fly RC planes.

My problem is charging my marine batteries fully after sitting for weeks
and them having just 1/2 of the capacity when discharged. After the next
charge however they have full capacity.

Cycling them before the first night solves this problem.

take care,
Rockett Crawford

----------------------------------------------------------------------------

Capella's Observatory (CCD Imaging)

Rockett, I'm sorry but I cant explain my argument better, lead acid batteries
have a finite number of times that they can be discharged to zero, also they
don't suffer from a "memory effect". I really don't know why you are noticing an
improvement but if it works for you...

Herm

Rockett Crawford <Rockett@...> wrote:

hermperez@... wrote:

this does no good to lead acid batteries, all you are doing is shortening its
life.

No, you are definitely wrong about the batteries I am using.
It does do a lot of good. I discovered this by accident. I noticed that
every time I went out for more than one night, the second night the batteries
had almost twice the capacity as they did the night before.

Finally I wised up and started cycling the batteries before a star
party rather than just charging them up.

Astropics

Paul Sterngold wrote:

--- Rockett Crawford <Rockett@...> wrote:

No, this is not normal. You have a defective hand controller.

Or it may be that you have the motors plugged into the wrong jacks on the
drive control box. (I've done this before- the scope keeps moving the DEC
axis! <g>) Be sure that you have the upper motor connected to DEC and the
lower one connected to RA.

But I would think the axis would merely be swapped in that case.

If that is not the problem, then indeed you have a defective drive system.
It is probably the hand controller but could possibly be the drive control
box.

Good point, there is a chance it could possibly be the drive control also.

Rockett Crawford

----------------------------------------------------------------------------

Capella's Observatory (CCD Imaging)

--- Rockett Crawford <Rockett@...> wrote:

No, this is not normal. You have a defective hand controller.

Or it may be that you have the motors plugged into the wrong jacks on the
drive control box. (I've done this before- the scope keeps moving the DEC
axis! <g>) Be sure that you have the upper motor connected to DEC and the
lower one connected to RA.

If that is not the problem, then indeed you have a defective drive system.
It is probably the hand controller but could possibly be the drive control
box.

Paul Sterngold

__________________________________________________
Do You Yahoo!?
Yahoo! Mail - Free email you can access from anywhere!

No, this is not normal. You have a defective hand controller.

Rockett Crawford


Tony Bonanno wrote:

Hi Everyone,

Just received my new GM-8 yesterday and my initial impressions are
very positive. I had never seen one before and purchased it on its
reputation. I think I've made a good choice. I'm sure I'll have
some questions for the group as I become more familiar with it and
already have one question regarding the hand controller.

Looking at the hand controller with the RA and DEC reverse switches
at the top, there is a diamond shape arrangement of four buttons. My
assumption was that the buttons opposite each other would control the
motion of the same axis. However, on this particular controller, the
TOP and LEFT buttons seem to work on one axis while the RIGHT and
BOTTOM buttons control the other axis. I've found it very
frustrating as it is not intuitive at all. Is this the normal
operation for the GM-8 hand controller or is my specific
example "wired wrong" ??

----------------------------------------------------------------------------

Capella's Observatory (CCD Imaging)

Hi Everyone,

Just received my new GM-8 yesterday and my initial impressions are
very positive. I had never seen one before and purchased it on its
reputation. I think I've made a good choice. I'm sure I'll have
some questions for the group as I become more familiar with it and
already have one question regarding the hand controller.

Looking at the hand controller with the RA and DEC reverse switches
at the top, there is a diamond shape arrangement of four buttons. My
assumption was that the buttons opposite each other would control the
motion of the same axis. However, on this particular controller, the
TOP and LEFT buttons seem to work on one axis while the RIGHT and
BOTTOM buttons control the other axis. I've found it very
frustrating as it is not intuitive at all. Is this the normal
operation for the GM-8 hand controller or is my specific
example "wired wrong" ??

Thanks for the help,

Tony

hermperez@... wrote:

this does no good to lead acid batteries, all you are doing is shortening its
life.

No, you are definitely wrong about the batteries I am using.
It does do a lot of good. I discovered this by accident. I noticed that
every time I went out for more than one night, the second night the batteries
had almost twice the capacity as they did the night before.

Finally I wised up and started cycling the batteries before a star
party rather than just charging them up.

Its definitely good for nicads but does not apply to lead acid batteries.

All you have to do is to promptly recharge the battery with a good automatic
charger, or float it at 13.8v...keep the electrolyte topped off etc..

I do charge it with a good automatic charger designed specifically for
marine batteries. I also charge them immediately when I get home to
leave them in a charged state.

all you possibly could want to know about rechargeable batteries, all types,
check it out here:

This is a good page, but it appears to only apply to small R/C packs
that go into models.

----------------------------------------------------------------------------

Capella's Observatory (CCD Imaging)

Paul Sterngold wrote:

The G11 should consume less than 1 amp per hour, but for safety's sake,
estimate that rate. The DSC's consumption should be negligible but again,
play it safe and estimate 0.5 amps per hour

The DSCs have a display heater which takes about 1/2 amp, but
only when the temperature drops below freezing. The digital drive
pulls about 1/2 an amp.


Capella's Observatory (CCD Imaging)

Hi everyone,
I am in the process of purchasing a used G-11 with Losmandy digital setting
circles and polar alignment scope from a fellow club member. After years of
using fork mounts, I'm still getting used to using German mounts and I have
a few questions that don't seem to be really covered in the manuals, mostly
about the DSCs. Fortunately, the current owner is allowing me to borrow the
mount before actually purchasing it so I can "kick the tires" and get any
questions answered up front.

1) The manual states that the polar bore scope should rotate freely when
inserted in the RA housing. However, after tightening the retaining ring,
the finder won't budge. Is it normal to have to loosen the retaining ring
slightly to rotate the polar finder?

2) Will the DSCs in alt-az mode with the G-11?

3) Will the polar scope give me a sufficiently close alignment that the DSCs
will work with a 1-star alignment?

4) Appendix A in the DSC manual describes a process for determining the +90
degree position for the telescope/mount that is necessary for a 2-star
alignment with a GEM. Shimming the mount may be all fine and dandy if you
have a permanent installation, but it sounds impractical if you have to
setup and take down the scope and mount for every viewing session. How
accurate does this process have to be? Will centering Polaris and setting
the mechanical declination circle get me close enough?

5) The illuminator and battery pack for the polar bore scope seems a little
cumbersome. Is there an illuminator available with a self-contained
battery?

I'm sure I'll have other questions as I start using the mount.

Thanks,
================================================
Ray Porter
Applications Analyst Programmer
Administrative Information Services, UNC-CH
Phone: 966-5878
email: ray_porter@...
dragon@...
Home Page:

"Meddle not in the affairs of dragons,
for thou art crunchy and taste good with ketchup."

--- In Losmandy_users@..., hermperez@w... wrote:

this does no good to lead acid batteries, all you are doing is

shortening its

life. Its definitely good for nicads but does not apply to lead

acid batteries.

All you have to do is to promptly recharge the battery with a good

automatic

charger, or float it at 13.8v...keep the electrolyte topped off

etc..

all you possibly could want to know about rechargeable batteries,

all types,

check it out here:



Herm

Rockett Crawford <Rockett@a...> wrote:

Thanks to all of you who responed. The battery is a lead-acid
battery sold by Pep Boys for boosting your car battery when needed.
The amp-hr rating is not listed. It was alway fully charged as
indicated by the pilot light (green) when the button was pressed.
Over charging may be the cause because I tend to leave the wall unit
charger plugged in all the time. In any case when used three days in
a row, it is recharded overnight and the third night failed after
about 4 hrs. I assume that the battery is a dud and leaving for
Sam's to buy another. Once again thanks.

This is called "cycling" by NiCad users. I don't know if the
concept applies to these batteries or not, but it definitely
makes a big difference.

Astropics

this does no good to lead acid batteries, all you are doing is shortening its
life. Its definitely good for nicads but does not apply to lead acid batteries.

All you have to do is to promptly recharge the battery with a good automatic
charger, or float it at 13.8v...keep the electrolyte topped off etc..

all you possibly could want to know about rechargeable batteries, all types,
check it out here:



Herm

Rockett Crawford <Rockett@...> wrote:

This is called "cycling" by NiCad users. I don't know if the
concept applies to these batteries or not, but it definitely
makes a big difference.

Astropics

I doubt it, most likely your battery pack is not in good shape. What kind of
batteries and how big is the pack made off?

I sometimes use a 5ah lead-acid gellcell and its good for two nights.

Herm


havriliak@... wrote:

The battery pack that I use claims that a radio or TV can be
operated for 20 hrs. On several occassions, by freshly charged
battery went dead driving the G-11 with DSC. I couldn't understand
this at first, and later concluded that a fine layer of bubbles
formed over the battery plates made it appear dead. So when it
happened again, I simpley shook the battery as hard as I could but to
no avail. Any comments, or does the G-11 draw about 5 times the
current of a radio or TV

Astropics

The G11 should consume less than 1 amp per hour, but for safety's sake,
estimate that rate. The DSC's consumption should be negligible but again,
play it safe and estimate 0.5 amps per hour. If you estimate 1.5 amps per
hour total consumption, you'll be very safe. It's probably about half that
in reality.

Was your battery fully charged before you used it? What is the amp-hour
rating?

Deep cycle batteries such as this should be recharged immediately after
use, no matter how low you've run them. Running them all the way down
and/or letting them sit in a partially or fully discharged condition
shortens their life.

They have no memory and can be discharged to any point before recharging.

I use a hefty Marine battery rated at 105 AH along with a smaller "Gates
Cyclon" 24 AH battery. The pair can run my scope, CCD camera, autoguider
and laptop for four nights without recharging, as I learned this past June
on Mt Lassen in California. Fortunately, I didn't have to use my dew
straps, as they are some of the biggest consumers of electrical power.

Paul Sterngold

__________________________________________________
Do You Yahoo!?
Yahoo! Mail - Free email you can access from anywhere!

I use a 34 amp hour marine battery (a small battery, about the
size used in rider mowers) for my G-11 /w DSCs and it lasts all
night long even in the winter.

I use marine batteries because unlike car batteries, they are
designed to be discharged almost completely without harming
them.

I also use two other 34 amp batteries to run my laptop and
CCD camera but I'm fixing to upgrade to two 68 amp hour
batteries because the smaller batteries are just borderline enough.

I have noticed something about marine batteries (don't know which
kind you have), that if you charge them up after a few weeks of
sitting, they don't have as much capacity. The longer they have
sat, the lower their capacity is.

However after I cursed at them for running completely down
in say 1/2 the time they should have and charge them up
fully again. Then they have full capacity and last much longer.

So what I now will do if I haven't been out for a month or so is
charge them up, run them down, and then charge them
up again before I go out.

This is called "cycling" by NiCad users. I don't know if the
concept applies to these batteries or not, but it definitely
makes a big difference.

Rockett Crawford


havriliak@... wrote:

The battery pack that I use claims that a radio or TV can be
operated for 20 hrs. On several occassions, by freshly charged
battery went dead driving the G-11 with DSC. I couldn't understand
this at first, and later concluded that a fine layer of bubbles
formed over the battery plates made it appear dead. So when it
happened again, I simpley shook the battery as hard as I could but to
no avail. Any comments, or does the G-11 draw about 5 times the
current of a radio or TV

----------------------------------------------------------------------------

Capella's Observatory (CCD Imaging)