3.7m Prime Focus Prodelin project: any ideas?

[Captain Jack]

Or buy a second 3.7m ;)

Probably easier...

 

[3virgul14]

Or buy a second 3.7m ;)

If only it was a digit cheaper

 

[3virgul14]

Hi dear experts!

Following up with the project, I have the dish ( 3.7 prodelin PF with polar mount and az el skew - superjack actuators and titanium controller )

Before we start the installation , the concrete platform was build to put the dish on. 150cm high and 2,5mx2,5m dimensions.

After 2 days of installation interrupted with rain showers and storms, we managed to put it on with the help of a crane.

Followed by bolting the lnb sticks and setting up the lnb, we made a test on 30w . Resulted in great disappointment as the weakest transponder for me 11519v10000 and 11529v10000 were just under 2db S/N..

I know its and amateur job we did and maybe i underestimated the difficulties but
I would like to ask for your ideas and checkpoints to correct this installation and also if you know any professional who could do this for a fee? Maybe ?


For comparison, I have the Famaval 2.4m with extension petals to 3.1m -motorized- and it gets about 8db from these tps..

 

[Channel Hopper]

For comparison, I have the Famaval 2.4m with extension petals to 3.1m -motorized- and it gets about 8db from these tps..

Please take an image or two of the feed and post them.

I have had a lot of previous experience with PF Prodelins and could pop over if there are cheap flights, a place to stay for the evening and sustenance on order.

 

[Channel Hopper]

You really shouldn't lean a ladder on the dish surface (I know everybody does it though). Can you also take some pictures of the dish surface edge on, from a number of angles, just in case it has distorted since laying flat on the ground. It does happen.

 

[John]

.... now that is awesome.
I need to drool over the installation & location for just a bit longer though but help will be on it's way.

 

[RimaNTSS]

Very nice! I wonder why the concrete box is only 150cm high? Could be at least 1,9m to go inside without hitting the head.
Check the geometry of the dish by stringing it. Also measure exactly diameter and the dept and then calculate position of the LNB.

 

[blademedia]

Yes very nice, I presume you have bolts for levelling the mount, one novice I read about fitted a large dish without them, now he's stuck with a big dish that doesn't track the arc

 

[3virgul14]

Al

Please take an image or two of the feed and post them.

I have had a lot of previous experience with PF Prodelins and could pop over if there are cheap flights, a place to stay for the evening and sustenance on order.

I can get the tickets for you and our holiday house has couple of extra rooms to accomodate as many days as you wish. I dont think its a 1 day job

Alright, here are the pictures a bit detailed as you asked for: hope it helps

 

[RimaNTSS]

It seems that geometry of your dish is far from perfect, and that, for sure, is the reason antenna is not performing good in Ku-band. So, the shape must be corrected.

 

[Captain Jack]

It seems that geometry of your dish is far from perfect, and that, for sure, is the reason antenna is not performing good in Ku-band. So, the shape must be corrected.

Yes, it's quite obvious in pictures that it's warped and not straight when viewed side-on.

Should be a heck of a performer once that's sorted though.

 

[Channel Hopper]

Agreed, the dish panels have either moved since they were assembled, or the reflector supports are not drilled correctly (it happens).

At least the feed is the correct one (minimal scalar )

It is possible to shake down the reflector whilst on the mount, raise the elevation to 90 degrees and undo every bolt betwee the reflector panels and the support trellis by two turns, shake well, and then tighten up everything from the outside in, ensuring the panel surfaces mate up on the front aspect.

Let me know the nearest airport to you and I'll - provisionally - check flights.

 

[3virgul14]

We do the shaking now, it has corrected itself to a degree but Im not %100 about the shape. I will make new pictures now

 

[Channel Hopper]

The other option is to take the whole reflector assembly apart and swop panels around, but this is not nice to do, especially in such temperatures.

Is the crane on long term loan ?

 

[3virgul14]

The other option is to take the whole reflector assembly apart and swop panels around, but this is not nice to do, especially in such temperatures.

Is the crane on long term loan ?

Nope but it is a friend's so could be used as much as needed .

I am quite close to Rodos airport ( we have only one here in the island) so its the target for flights

Here are the strings and how the panels align now ; what do you say masters?

 

[RimaNTSS]

There is still some gap between the strings, but is should not be so big.... I think. Try to tune to your favorite satellite and check the reception.

 

[3virgul14]

Very nice! I wonder why the concrete box is only 150cm high? Could be at least 1,9m to go inside without hitting the head.
Check the geometry of the dish by stringing it. Also measure exactly diameter and the dept and then calculate position of the LNB.

The manual said it focal distance is at 24 inches so we placed a 137cm stick between the central lines of the dish and feedhorn. I am hoping this is correct.

1.90 for the height was too high as the top of the dish and lnb would be out of the reach..

 

[Channel Hopper]

Much better from the second image, however the ideal way to measure is with the strings midpoint on each panel and check for them meeting in three planes. (They will always coincide in two planes when tied to the segment divides since these are identical 45 degree positions.)

 

[archive10]

Blimey, that's a big beautiful dish!

We debate polar mounts earlier in this thread.
Did you obtain a different dish, or did you find a polar mount, and if so where? It looks official...

 

[Channel Hopper]

I am quite close to Rodos airport ( we have only one here in the island) so its the target for flights

Checked Rhodes airport earlier, from Gatwick (Luton has nothing until end of May).

Earliest available is Satuday 15th returning Wed 19th and some £350, plus I'd have to park there for the duration. So £400 give or take £10.


They fill up rather quickly , next is 19th returning the 22nd at just over £300.

We have some time therefore to fix remotely, unless you have friends outside Easyjet that fly from London.