Thank you John,
These are also some of my thoughts. Moment-arm especially.
RA,Dec cables checked.
Dither is after 6-8 frames, and frequently is RA only, spiral. I
have always (over the life of the mount) had PHD2 timeout waiting
for settle after dithers, so I make them infrequent and mild.
TVC = 0
The GM811 has an instrument carrying capacity of 50lbs imaging,
65lbs visual. I understand that to be exclusive of counterweights,
so I believe well within limits.
However, the moment-arm interests me. The counterweights were
previously 2x11 lbs near the bottom of the CW shaft, and this
particular run I added a 7# CW to the bottom to move the 2 11# CWs
up. They are still not up to top.?
Also, the scope itself is 50" from front edge to camera rear.
That would seem to add a bit of moment arm as well.
I am using an RAEXT, so the Dec axis is also a bit farther from
RA.
RA and Dec are both balanced, slightly East and Camera heavy. Dec
was actually almost too balanced this run.
Thanks!
Dale
On 3/2/25 11:25 PM, John Kmetz via
groups.io wrote:
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Dale,
?
This seems bizarre behavior. Dec (which should be in red)
typically will drift in one direction if PA is off. If seeing is
bad it should vary randomly. Having a repeating pattern I think
is something software other than hardware as the Dec motor
should only be rotating back and forth as corrections are
needed.
?
Some random ideas:
-Are RA and Dec cables reversed (probably not)?
-Are you dithering after every frame and is the dither large?
-Have you checked TVC in the hand controller, perhaps too
large a value?
-Dec MinMo seems large - I'm seeing changing values from 0.2
to 0.35
-57# on an GM811 seems, like a lot. If a G11 has 60# payload,
the 811 is less, I think. Are your counterweights all at the
bottom of the CW shaft? Perhaps too much moment-arm the mount
can't handle.
?
All I could think of for now.
?
Good luck.
?
John
--
_____________________________________________________________________________________________________________________________________________________________________________
Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep
controller; SkyShed design roll-off observatory; ZWO
ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field
flattener; Celestron C925 Edge HD with 0.7XFR, William Optics
Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and
PixInsight user
