3.7m Prime Focus Prodelin project: any ideas?

[Channel Hopper]

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...

That is the real deal, but limited to 75 degree movement (80 with a bit of filing, 86 with a small weld or three)

 

[archive10]

That is the real deal, but limited to 75 degree movement (80 with a bit of filing, 86 with a small weld or three)

Very nice!

 

[Channel Hopper]

They were OK, but the US company was never really interested in providing a proper polar mount for their dishes, no matter how much I tried.

 

[3virgul14]

Mr. Kypros Pambou from this forum, claims that the dish is made for C band and Ku band performance will be much lower. That is why its underperforming. According to his statement


Today I will realign the dish and try to make test to see about any improvement.

One question: how to find the optimum position for the skew on lnb?

 

[archive10]

Mr. Kypros Pambou from this forum, claims that the dish is made for C band and Ku band performance will be much lower. That is why its underperforming. According to his statement

Hmm. I may be wrong, but really, I am not so sure about that.
Do you know how old the dish is (it looks newish)?

As far as I can see, all the newer 3.7m Prodelin models share the same reflector, and all documents refer to 3.7m C/Ku band when mentioning the dish.
TBH it would be silly of Prodelin to make a special C-band only versions at this day and age...

We should ask the opinion of @Channel Hopper, he's probably the most experienced in the Prodelin series.

 

[s-band]

One question: how to find the optimum position for the skew on lnb?

I see you have a TBS6903. The way I do that (and other tweaks) is to use EBSPro on the PC and the Android app, via WiFi, to monitor the s/n. The voice and tone feedback means that you can adjust things without having to look at a screen. Choose a transponder with a low s/n as it will be more sensitive to small changes.
Downloads – EBSpro

 

[3virgul14]

It is a 2016 made dish and manual indicates that kU band with polar.

Hmm. I may be wrong, but really, I am not so sure about that.
Do you know how old the dish is (it looks newish)?

As far as I can see, all the newer 3.7m Prodelin models share the same reflector, and all documents refer to 3.7m C/Ku band when mentioning the dish.
TBH it would be silly of Prodelin to make a special C-band only versions at this day and age...

We should ask the opinion of @Channel Hopper, he's probably the most experienced in the Prodelin series.[/

 

[blademedia]

Have you checked the lnb is pointing in the correct position, it needs to be spot on,
2.4 DH Antenna installation

You may have peaked the signal on a side lobe of the dish and not on a main signal. Normally the side
lobes would be considerably less signal than the main signal but if you don't have the feed in the correct
place then this would have the effect of decreasing the main lobe and increasing the side lobes signals.

 

[Captain Jack]

You may have peaked the signal on a side lobe of the dish and not on a main signal.

Good point - I've seen this very same thing in the past on an offset. Spent quite some time pondering why the signal was so carp...!

 

[blademedia]

Good point - I've seen this very same thing in the past on an offset. Spent quite some time pondering why the signal was so carp...!

So have I lesson learnt

 

[Channel Hopper]

Hmm. I may be wrong, but really, I am not so sure about that.
Do you know how old the dish is (it looks newish)?

As far as I can see, all the newer 3.7m Prodelin models share the same reflector, and all documents refer to 3.7m C/Ku band when mentioning the dish.
TBH it would be silly of Prodelin to make a special C-band only versions at this day and age...

We should ask the opinion of @Channel Hopper, he's probably the most experienced in the Prodelin series.

The panels for the 3m/3.4m and 3.7m are all Ku and C band compatible. From memory only the offset reflectors were supplied in C or Ku configuration and that was years ago. I'd have to check the assembly manual when I get back to the office but I'm certain the reflector panels were/are given two serial numbers only (with hole for feed arm and without hole).

Since you have the corrrect feed for the dish (was the package a 1375-010 or 020 ?) the whole system relating to the completed order is put together from specific batches of metal and plastic parts specified at time of manufacture.

There are some other checks that can be carried out on panel build quality, but I would have to be on site with an analyser to verify.

 

[Channel Hopper]

One question: how to find the optimum position for the skew on lnb?

Optimum skew is checked with minimum signal on the opposite polarity. For this the best way is with an analyser that has Eb/No readout.

 

[nelson_b]

Good point - I've seen this very same thing in the past on an offset. Spent quite some time pondering why the signal was so carp...!

Got this result too when i first setup the 2.4 offset ... was well disappointed until i clicked to what was happening

 

[Channel Hopper]

Good point - I've seen this very same thing in the past on an offset. Spent quite some time pondering why the signal was so carp...!

There are patterns available for the Prodein antennas that show the expected level of sidelobe, the earlier images however suggest the results obtained on site are down to the distorted reflector assembly.

 

[Channel Hopper]

Petal part numbers

0179-260 and 0179-261.

0.37 f/d dish with focal length fixed at 1371.6 mm (54 Inches)

 

[Channel Hopper]

Btw, the 3.7m dish not far from here.

 

[3virgul14]

That one has a different polar mount and professional motor I reckon?

 

[Channel Hopper]

It is a fast track (dual axis ) mount for tracking weather satellites, on top of the University of Surrey (Guildford)

 

[moonbase]

Has the alignment issue with the dish been resolved?

Rgds

 

[Channel Hopper]

Easter plays an important part of local festivities so most of the island has been on a full holiday until today.