Upside down offset dish

[7mdish]

Ah, yes. Any tolerance between the pole and the polarmount 'sleeve' is going to be an issue. For a 100mm post, a gap of 1mm means the possibility of up to 2% tracking error in all directions (as a comparison the 6.5" post with 1mm gap brings the error down to around 0.45%).

It was alluded to in this thread around post #14

Adapting IRTE Stand for use with 2.4m Dish

Hi all after some advice, I currently have a 2.4m CM languishing in the garage whilst waiting to purchase a polar mount/stand/king post whatnot I have the chance to purchase this stand which was previously used for a 1.8m tin foil dish ie fortec star petal Could this be adapted to take my 2.4m...

www.satellites.co.uk

The later IRTE polarmount has quite a deep sleeve which is clamped around the pole top and bottom, If bolted to the correct tolerance it doesn't move at all, leaving only the actuator rose joints and polar mount bearings as candidates for tracking issues.

I hope the new stand is close to the inside diameter of the polarmount ordered, otherwise you will end up with movement unless welded shut.

It was exactly the issue you mentioned. We thought that adding more bolts between polarmount sleeve and pole could be enough for a stronger clamp but it was not true.
The polarmount had tolerances that we could not accept to avoid big tracking errors.
As I said, probably we made a bad mistake not considering this problem in the right way, so we must stop the job thinking to a new, specifically built, 100mm pole.
Having a new pole, built on-demand by a local manufacturer, we can be sure that when we resume the installation this problem will be solved. Unfortunately we must wait until September, after summer holidays.
This is the story. I let you know. Thanks.

 

[Channel Hopper]

It was exactly the issue you mentioned. We thought that adding more bolts between polarmount sleeve and pole could be enough for a stronger clamp but it was not true.
The polarmount had tolerances that we could not accept to avoid big tracking errors.
As I said, probably we made a bad mistake not considering this problem in the right way, so we must stop the job thinking to a new, specifically built, 100mm pole.
Having a new pole, built on-demand by a local manufacturer, we can be sure that when we resume the installation this problem will be solved. Unfortunately we must wait until September, after summer holidays.
This is the story. I let you know. Thanks.

Please post some pictures of the polarmount you have, from all angles. It might assist minimising disappointment second time round.

 

[Channel Hopper]

Anything forthcoming ?

 

[7mdish]

Almost ready.
Summer break was gone, and the new pole was delivered.
We made a completely new job, building a proper concrete and installing the pole on the roof.
Now the SSS polarmount is perfectly clamped to the matching pole and all tolerance issues was solved.
After that, we installed the dish and all additional parts like actuators and feed.
The job is not finished yet, and as soon as it will be I will post some pictures here.
But... our first test with the Promax meter are absolutely promising.
The dish seems FANTASTIC! In particular, the motorised 2-ports Ku-band feed by Viking seems perfectly matching with the dish.
This was a critical point as you remember (see previous posts), but I was optimistic due to the similar design between CM and Prodelin dishes.
And it is. We lost more than one hour for a perfect tuning, but finally the results seem very good.
Very very strong signal from most satellites that we tested.
Also, the polarmount and both actuators from SSS seem very strong, no problem to move such a big and heavy dish in all directions until the extreme positions.
Not sure about East and West limits yet because we tested both motors with a power supply on the roof, we must still connect the RC2000, but I'm pretty sure that the coverage will be between 60 East and 40 West at least, probably more. Not bad I believe in my location.
I think that during next week we are able to connect the positioner and check carefully all setup to finish the job, but most part of the installation was done.
More update soon, including pictures. Thanks.

 

[RimaNTSS]

More update soon, including pictures.

Yea, pictures are missing. Long time waiting.

 

[7mdish]

Yea, pictures are missing. Long time waiting.

Long time waiting for me, too! It was a pain without a big motorised dish!

 

[7mdish]

Finally the job is finished. The dish is installed on my roof and perfectly working.
I confirm that all setup is really fantastic. In particular, the feed is unbelievable. In a such high grade dish, a rotating feed can be very important to make perfect skew on each satellite. And, most important, this specific feed is perfectly matching this dish.
Making the final test with the meter, we got an unbelievable 92 dBuV signal on Hotbird. Yes it is the strongest satellite, I know that, but we never seen such signal with larger dishes, too.
More than 80 dBuV on many feeds at 7E and 10E. Very happy.
A first picture showing a global view, more detailed pictures will follow.

 

[7mdish]

More pictures of my new setup, taken during the installation on the roof.

 

[7mdish]

More pictures.

 

[7mdish]

Last pictures.

 

[RimaNTSS]

As I see, only birds did not like your antenna. Great job, Marco!

 

[moonbase]

Finally the job is finished. The dish is installed on my roof and perfectly working.
I confirm that all setup is really fantastic. In particular, the feed is unbelievable. In a such high grade dish, a rotating feed can be very important to make perfect skew on each satellite. And, most important, this specific feed is perfectly matching this dish.
Making the final test with the meter, we got an unbelievable 92 dBuV signal on Hotbird. Yes it is the strongest satellite, I know that, but we never seen such signal with larger dishes, too.
More than 80 dBuV on many feeds at 7E and 10E. Very happy.
A first picture showing a global view, more detailed pictures will follow.

Well done, you have put a lot of time and $$$ into this project, I am pleased that it has all come good for you.
Looking forward to some details of satellite feeds captured by the dish.

 

[7mdish]

Oh yes... many birds here on the trees, and on the dishes!

 

[RimaNTSS]

When/if you have possibility, change those 4 screws to ones with flat heads (furniture screws).

 

[7mdish]

Well done, you have put a lot of time and $$$ into this project, I am pleased that it has all come good for you.
Looking forward to some details of satellite feeds captured by the dish.

Yes, the only really bad point was... $$$! But now I'm happy, money well invested.
Now I need a little bit of time to make deeper test on weaker satellites and program all satellites in my RC2000a. Then, I will update with reports on some good feeds. Thanks.

 

[anto@]

congratulations great job, but I would ask you for more information not on signal db, which are also obtained with other less expensive systems
but I would ask you the value of mer or of the noise margin since a field meter was used
or if you use tbs cards
obviously for signals that reach your latitude with medium-low powers
thanking you for the beautiful pictures, I congratulate you again

 

[7mdish]

I tested only main center satellites for now. On most feeds at 7E and 10E (weaker and weaker than Hotbird obviously) MER values are always between 12 and 14 dBs, measured with TBS5925 and EBS Pro since Promax meter was not mine obviously, and we had no time to make deeper tests with that meter during installation.
But I think that values from TBS are reliable, too. Also, today during a shower one feed at 10E (SR was 7200) lowered from 14 to 11 dB, so largely lockable and the rain was very strong.
So, a very satisfying result I believe.

 

[anto@]

you could try the east beam tp on 4 west and 42 east
and the tp 11175 on the 46 est
you would immediately put your system to the test
since above me for a few tens of KM

thank you

 

[anto@]

as far as the tbs is concerned, the value read in db is similar to the MER value that the instrument releases

 

[7mdish]

Just performed a quick test on Eastern Beam at 4W but I have very weak signals. Tested 10890V and 10926V, both around 2 or 3 dB, obviously very far from lock.
Maybe a deeper test would be needed.
Better situation at 25.5 East. Here I locked a frequency near 11 dB (did not remember which one), but I'm not sure if it was really 25.5 East instead of 26 East.
I must finish programming the RC2000A controller on all satellites, then I can play more comfortably. Thanks.