Ka with Prodelin/Viasat 1.2m Band B

[s-band]

I put a Prodelin 3122 Ka dish on the CM1.8 polar mount. I could not work out how to get the Viasat ODU working so I bodged a Gilat 2.5W ODU on the platform.(only the RX connected - it wasn't me @Llew). The sky/ground noise figure of the whole thing measured about 2.9dB, not fantastic but it has all the diplexer stuff to get through. The dish is 0.8f/d, I think, so I'm not sure how well the Gilat feed is matched.



I don't know my way around Ka so I mistook 9E for 0.7W and used the wrong starting point - doh! That meant that I couldn't work out what was where. I knew something wasn't right as I had to keep adjusting the declination. I sorted it out after with reference to the scans on satellitescommunity.de. If I still have it wrong, let me know. I didn't have time to physically switch polarisation so I only did RHCP. One TP on 0.7W is really strong.

Plots, L to R: 0.7W, 0.7W, 9E, 28E

 

[Llew]

I put a Prodelin 3122 Ka dish on the CM1.8 polar mount. I could not work out how to get the Viasat ODU working so I bodged a Gilat 2.5W ODU on the platform.(only the RX connected - it wasn't me @Llew). The sky/ground noise figure of the whole thing measured about 2.9dB, not fantastic but it has all the diplexer stuff to get through. The dish is 0.8f/d, I think, so I'm not sure how well the Gilat feed is matched.

View attachment 106577

I don't know my way around Ka so I mistook 9E for 0.7W and used the wrong starting point - doh! That meant that I couldn't work out what was where. I knew something wasn't right as I had to keep adjusting the declination. I sorted it out after with reference to the scans on satellitescommunity.de. If I still have it wrong, let me know. I didn't have time to physically switch polarisation so I only did RHCP. One TP on 0.7W is really strong.

Plots, L to R: 0.7W, 0.7W, 9E, 28E

View attachment 106578 View attachment 106579 View attachment 106580 View attachment 106581

Nice results s-band - and no, my shenanigans picking the wrong LNB when trying a Newsnet scan wasn't you firing up the TX

Don't know if you have this pdf for the Gilat ODU?

https://www.filiago.de/content/uplo...tion_and_Pointing_User_Guide_October_2016.pdf

 

[s-band]

Thanks, Llew, I hadn't seen that. Tech detail on ODUs is hard to find, I presume because they don't want people messing with them;)

What is the stuff between 19.15 and 19.45GHz on this plot? I don't think it was from exactly the same orbital position as the main signals above 19.7GHz. The signal at 18.8GHz is an internally generated spurious.

 

[Llew]

What is the stuff between 19.15 and 19.45GHz on this plot?

Can't get down that far with my present setup.

Any idea where these ACM feeds are located with your Gilat s-band? Around 19.7 - 19.85, just to the west of 28.2E, may be 26E. Frequencies may not be exact, as I'm using my Hughes with adjustable DRO screw, and may be out of true LOF.
Can't find any info in our threads here at the mo.

 

[s-band]

Can't get down that far with my present setup.

Any idea where these ACM feeds are located with your Gilat s-band? Around 19.7 - 19.85, just to the west of 28.2E, may be 26E. Frequencies may not be exact, as I'm using my Hughes with adjustable DRO screw, and may be out of true LOF.
Can't find any info in our threads here at the mo.

No idea, I have just been testing things and have to put the dish in the shed when not in use. If I get a chance I'll look again. The only ones I can see from hvdh's list, on band B, are BADR 5 & 7 at 26E and possibly Eutelsat 25B at 25.5. KA Band satellites in Europe

I presume that neither Feedsat nor qwer can see it from their locations.

 

[Llew]

No idea, I have just been testing things and have to put the dish in the shed when not in use. If I get a chance I'll look again. The only ones I can see from hvdh's list, on band B, are BADR 5 & 7 at 26E and possibly Eutelsat 25B at 25.5. KA Band satellites in Europe

I presume that neither Feedsat nor qwer can see it from their locations.

Most likely one of the BADR 7 KA Band B spotbeams has come into operation over my location. There are dedicated MENA KA beams, but I wouldn't be able to receive those where I am.
Won't be Eutelsat 25B at 25.5E, as that uses KA Band D. Unlikely also to be BADR 5 KA Band B, as that footprint is way away from me.

Perhaps @John or @Vipersan could check to get an idea of the footprint reach in the UK?

 

[s-band]

Found it, it is LHCP. It looks like I am further into the beam as the TPs are stronger here, closer to London. I haven't checked the frequency of the Gilat but it probably isn't too far off, the spec is +/-25ppm.



@Llew move/copy to your BADR thread?

 

[John]

Most likely one of the BADR 7 KA Band B spotbeams has come into operation over my location. There are dedicated MENA KA beams, but I wouldn't be able to receive those where I am.
Won't be Eutelsat 25B at 25.5E, as that uses KA Band D. Unlikely also to be BADR 5 KA Band B, as that footprint is way away from me.

Perhaps @John or @Vipersan could check to get an idea of the footprint reach in the UK?

Sorry Llew / Graham, a bit late picking up on this ..... which satellite is it and is it band B Ka LHC ?. I'll swing the Ka SL3 into focus on the 1.25 Gibby.

 

[Llew]

Found it, it is LHCP. It looks like I am further into the beam as the TPs are stronger here, closer to London. I haven't checked the frequency of the Gilat but it probably isn't too far off, the spec is +/-25ppm.

View attachment 106629

@Llew move/copy to your BADR thread?

Yes, I have made a new thread recently, and corrected the Hughes LOF.
I'll leave this thread here for the mo, and copy your post there.
Cheers.

 

[Llew]

Sorry Llew / Graham, a bit late picking up on this ..... which satellite is it and is it band B Ka LHC ?. I'll swing the Ka SL3 into focus on the 1.25 Gibby.

Yes John, Band B on 26E. I get a reasonable signal with my Triax TD88, s-band better with his Gibby 1.25.
Seems it's good in the UK, but in the absence of any reports from outside the UK at present, don't know how tight the ootprint is.

Nothing particularly interesting there, just checking for records' sake.

 

[John]

Yes John, Band B on 26E. I get a reasonable signal with my Triax TD88, s-band better with his Gibby 1.25.
Seems it's good in the UK, but in the absence of any reports from outside the UK at present, don't know how tight the ootprint is.

Nothing particularly interesting there, just checking for records' sake.

Thanks Llew, can i trouble you for a screen grab off your promax showing the same spikes as what Graham is showing on the Crazyscan plot and showing the correct frequencies .... i'm having a bit of trouble remembering what LO to use on the SL3. Cheers.

 

[Llew]

Promax view. +/- one or two MHz maybe, Hughes LOF may be slightly off.

 

[John]

This is the trace from my Promax, running LO for SL3 lnbf @18.046 using Gibby 1.25 .
......................................................................................................................................................................................................................................................................................

 

[Llew]

So, spot beamed at possibly Midlands/S.E UK area, pending any other checks by anyone else.

 

[s-band]

I added 60kg to the base to stop it waving in the wind, set it up a bit more carefully today and tried both polarisations. The ODU will go down to 18.5GHz but it can only do circular polarisation without a lot of work. It also goes up to about 20.5GHz.
My first TV on Ka 19.2E UnireSat, ITV Newsnet and a feed on 18751, 5500, 3/4



Scans L to R: 0.7W R, 19.2E, R, 26E L, 28E R, 28E L, 37E R

 

[John]

I added 60kg to the base to stop it waving in the wind, set it up a bit more carefully today and tried both polarisations. The ODU will go down to 18.5GHz but it can only do circular polarisation without a lot of work. It also goes up to about 20.5GHz.
My first TV on Ka 19.2E UnireSat, ITV Newsnet and a feed on 18751, 5500, 3/4

View attachment 106649 View attachment 106651 View attachment 106652

Scans L to R: 0.7W R, 19.2E, R, 26E L, 28E R, 28E L, 37E R
View attachment 106643View attachment 106642View attachment 106645 View attachment 106641View attachment 106646View attachment 106644View attachment 106647

Nice one .... Another bit of surplus kit to add to the list for a cheaper option to get onto band A Ka telly then G. Would be interesting to see the results for 18GHz Ver sigs by removing the poloriser and re-rigging it up for either V or H .
Expected dB levels for V sigs on the Newsnet freq on my 1.25 Gibby can range from between 11.5 - 15dB depending on weather, the other freq used on 18GHz V for the regional Tv are usually lower ... around 8 to 11dB. The Nag feed stuff on 18751 H area are stronger, usually around 16 to 17.5 dB depending on weather.

 

[s-band]

Nice one .... Another bit of surplus kit to add to the list for a cheaper option to get onto band A Ka telly then G. Would be interesting to see the results for 18GHz Ver sigs by removing the poloriser and re-rigging it up for either V or H .
Expected dB levels for V sigs on the Newsnet freq on my 1.25 Gibby can range from between 11.5 - 15dB depending on weather, the other freq used on 18GHz V for the regional Tv are usually lower ... around 8 to 11dB. The Nag feed stuff on 18751 H area are stronger, usually around 16 to 17.5 dB depending on weather.

Thanks for the useful comparison. Allow 3dB for polarisation and it is still a few dB below yours for ITN.
It's not as simple as removing the polariser, the in and out guides are different although it may be worth try to bodge it on there. It needs the IF to go down to 250MHz to get 18.5GHz and the Ka filters may be rolling off. It is quite a lump (>2kg) so you need a decent support. Below is an internal pic of the LNB.
I'm still looking for another one or 2 if anyone finds a source.

 

[s-band]

Would be interesting to see the results for 18GHz Ver sigs by removing the poloriser and re-rigging it up for either V or H .

@John, I pulled one apart fully. I must have been thinking about the Viasat one. The waveguide does match between the feed and the ODU. However, the location rings around the screw holes are only on the polariser and the feed fixings need to be drilled out. The ODU will need to be moved towards the dish by the length of the polariser. It will be naturally vertically polarised (probably). Turning the ODU round for horizontal will raise the feed but a tweak of declination will fix that (and plenty of gaffer tape). Maybe another day.

 

[John]

@John, I pulled one apart fully. I must have been thinking about the Viasat one. The waveguide does match between the feed and the ODU. However, the location rings around the screw holes are only on the polariser and the feed fixings need to be drilled out. The ODU will need to be moved towards the dish by the length of the polariser. It will be naturally vertically polarised (probably). Turning the ODU round for horizontal will raise the feed but a tweak of declination will fix that (and plenty of gaffer tape). Maybe another day.

View attachment 106662 View attachment 106663

Thanks for taking it apart, ..... that's an interesting little arrangement going on in the throat of that feed, not seen that done before.

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[scopus]

Certainly looks a fair lump..