Major Catastrophe ...

[TJExcalibur]

VS,

That's an interesting point re the EchoStar 3600 taking the agc levels from the analogue tuner. I did not know that, I had assumed it was interrogating the digital tuner when autofocusing on a satellite. It explains why my AD3600 often places the dish a few units off the maximum signal point when moving to another satellite. Its given me very good service over the years but perhaps its time to replace it with a Titanium ASC1.

Rgds

Not so sure. http://xxx.amazon.co.uk/ASC1-Satellite-Positioner-Actuator-Controller-Black/dp/B00HUJA6NA

 

[Vipersan]

Not so sure. http://xxx.amazon.co.uk/ASC1-Satellite-Positioner-Actuator-Controller-Black/dp/B00HUJA6NA

Indeed TJ ...
The review/description doesnt actually say 'auto-focus'...

 

[moonbase]

Indeed TJ ...
The review/description doesnt actually say 'auto-focus'...

No, the Titanium ASC1 does not have auto focus. I should have indicated that I was thinking of replacing the EchoStar AD3600 with a Titanium ASC1 rather than use a v-box. The Titanium ASC1 has polarity control which a v-box does not, the polarity control will be useful to me.

 

[Vipersan]

Well ..I guess I can start looking again for this discrepency ...
Did another experiment this morning..
Put a paint marker on the mag wheel edge with carl at 1W ...and a second paint line on the reed for reference ..
Sent the dish to 28E ...and back to 1W ..the marks closely aligned ...then sent the dish to 30W and back ..
Again the marks closely aligned ...
but how about single stepping ??
I single stepped until the line on the wheel reappeared ..
It turned out to be 4 clicks ...therefore 4 magnetic hotspots on the mag wheel..
Ok we are now dealing in multiples of 4 ..
So took a snap of this error and went on to 8 and then 16 ..
Same amount of error roughly ....in both cases ..
So in conclusion ...I was right about the pulse length being a factor but only when in close proximity (within 4 clicks of the target)
Not over distance where the errors appear to average out ...being accurately counted within that 4 click frame ...thus returning to almost the same spot..
This is fixed ...and in conclusion any minor error can only really be within 4 clicks
Single stepping will show small errors within this 4 click window ...but can correct themselves over distance
Which I guess is why the target lands close but needs fine tuning on a big dish at Ka once landed..
any greater errors than 4 clicks wide must be within the motor/dish structure.
Comments welcomed.
rgds
VS

 

[moonbase]

VS,

Just an idea, but have you thought about changing the mag wheel for one with more magnetic hot spots? I know they are available with 3 hot spots per wheel revolution, they might possibly be available with 4 hot spots? Without removing a mag wheel from a motor I am not sure how many hot spots they have as shipped from the factory?

 

[Vipersan]

Well ....have spent many hours today and still not solved this conundrum ..

Took a positioner outside and watched the dish move but cannot see where this error creeps in ..
Everything has been tightened up as best I can and can see no play anywhere ...but returning to 1W even in Ku is a problem unless I overshoot ..then return to 1W ..
Something has play but no idea what ?? or indeed a miscount of pulses whilst shifting the dish either side of top dead centre ...
I dont appear to miss by much at all providing I stay on the same side of the arc ...but going over to the otherside introduces error on return ....unless as I say I overshoot then return ...
It's a mystery to me and one I'm having problems solving ???
rgds
VS
I accept there were probably errors before the accident but not to this extent of that I'm sure..

 

[Vipersan]

VS,

Just an idea, but have you thought about changing the mag wheel for one with more magnetic hot spots? I know they are available with 3 hot spots per wheel revolution, they might possibly be available with 4 hot spots? Without removing a mag wheel from a motor I am not sure how many hot spots they have as shipped from the factory?

The mag wheel in the Moteck already has 4 hotspots ..
Yes it would be beneficial to have more but not sure how many you could comfortably have in such a small radius device without actually introducing errors due to not having definate off spots as well ..
to many hotspots might actually make the situation worse as the reed contacts would not stay open long enough..
rgds
VS

 

[Vipersan]

Hmm ..
This looks interesting and promising ..
The dish doesnt return exactly where I want it to ..but the errors seem less pronounced ...
Pole top wobble ..
ie the clamp ..therefore the motor ...therefore the dish listing to left or right either side of TDC ..
not a visible quantity to the naked eye ..but there is space to insert a couple of thin penny washers at the front of the top lip of the clamp ..
I popped a couple in at TDC ...and the return from E or W is closer to correct ..
ie ..stopped the wobble ??

Looks like the top clamp lip is not exactly a right angle ??

 

[Vipersan]

Might get away with driving these washers in hard for a temporary fix but maybe have to jack up the whole assembly to do the job right..
IF this is indeed the problem ..

 

[Vipersan]

So -- jacked up the dish ..removed the pole top plate ..
..Now re-shaped to fit inside the clamp better ..
Now to spray it with zinc paint ..and re-fit..
If this doesn't fix the pole top wobble ...I'm out of ideas..
rgds
VS

 

[Vipersan]

Not perfect but a helluva lot better ..
from 42E to 45W ...Carl returns to 1W with only 1db variation now ..
before it could be as much as 4db..
Id say this was indeed the crux of the problem ...but time will tell ..
rgds
VS

 

[Vipersan]

Ok ...just finished putting back all the sat positions I can see currently in Ku ....from 42E to 45W ..and Carl now stops at TAY on Turksat and RASD on 45W ..with a locked picture.
Yes I still need to fine tune a little crossing such a large expanse of arc ..but the signal when it arrives it not less than 80% Q on the TM5402...
I guess thats heading the right direction cos I couldn't do that this morning..
Just crossing my fingers now that nothing changes suddenly..
rgds
VS

 

[Vipersan]

...also true of BBC world news at 1W ...which lands with Q 85 when arriving from 45E and Q94 when arriving from 42E ..
So ..still some slack in the system I guess ...but not as bad as before.
There may be some 'play' in the motor itself ...or a miscount ...or it's simply the motor labouring to shift the heavy lnb cluster..
It's good ...but it's not Carling ..

 

[Vipersan]

So I think I finally solved the mystery ..
Sadly I can do nothing about it ...
Teeth wear possibly on the prime gear ...not that I can see any ?
Marking the prime gear and carefully watching it whilst at 1W I can see the tiniest bit of movement of the mark when gentle pressure is applied to the dish and exo ..
No detectable sideways movement of the worm drive and bearing assy..
So unless it is possible to cause the worm to rotate slightly by physically moving the dish ....which is doubtful considering the gearing ...then I can only conclude there is the smallest amount of slack where the worm meshes with the prime gear ..
Maybe this amount of play is designed in ? as tight fitting teeth meshing with a worm drive _could_ possibly cause problems with movement..
ie too much friction ?
The degree of error is about 3 to 4 'clicks ' and translates as about 5 (Quality) of signal on the TM5402 when approaching either from E or W ..
This error would be further magnified by a large dish with a tight beam..
Comments welcome
rgds
VS

 

[Trust]

So I think I finally solved the mystery ..
Sadly I can do nothing about it ...
Teeth wear possibly on the prime gear ...not that I can see any ?
Marking the prime gear and carefully watching it whilst at 1W I can see the tiniest bit of movement of the mark when gentle pressure is applied to the dish and exo ..
No detectable sideways movement of the worm drive and bearing assy..
So unless it is possible to cause the worm to rotate slightly by physically moving the dish ....which is doubtful considering the gearing ...then I can only conclude there is the smallest amount of slack where the worm meshes with the prime gear ..
Maybe this amount of play is designed in ? as tight fitting teeth meshing with a worm drive _could_ possibly cause problems with movement..
ie too much friction ?
The degree of error is about 3 to 4 'clicks ' and translates as about 5 (Quality) of signal on the TM5402 when approaching either from E or W ..
This error would be further magnified by a large dish with a tight beam..
Comments welcome
rgds
VS

At your pictures in the beginning of this topic i am pretty shure you can adjust the position of the worm by bringing it more close to the main gear

 

[Vipersan]

At your pictures in the beginning of this topic i am pretty shure you can adjust the position of the worm by bringing it more close to the main gear

Yes indeed ...there is room for adjustment ..but this is maxed out I suspect..
The holes in the casing that hold the ends of the worm assy bolts wont allow for any more I dont think ..
I could elongate them with a file but 'tis possibly risky..
rgds
VS