Advice on 1.9m prime focus dish & 4.8'e

[trev1978]

Hi all,

I had an official standard definition Viasat sub to 4.8' and was able to pull in the northern beam using my 1.9m prime focus- however my signal was weak and i did get picture breakup in the evenings. Viasat changed to HD boxes in the summer and i haven't as yet renewed the sub as I wasn't confident of pulling the HD channels as I assumed i would need a much stronger signal for this. I was never 100% happy with my dish setup and i have have been making some improvement. There was a slight warp in the dish which I have now corrected (divide dish into 12 segments with fishing line) and I discovered that the LNB wasn't 100 % centred on the dish. I am hoping that correcting these two items will help to bump of the signal.

I have a small portable standard def signal meter. Could anyone advise on what would be a good TP for me to max out the signal to. My meter won't read the HD sports channels that I am actually looking for.

Also when I set up the dish 6 years ago I bought both invacom and inverto blank LNB's. I ended up using the inverto as from memory it was pulling better quality on the horizontals. Has there been any further developments in LNB's for prime focus dishes? I am using the invacom scalar feedhorn.

Thanks,

Trev

 

[RimaNTSS]

Hi Trev! Sorry to hear you still have reception problems from Astra4 Nordic beam. Unfortunately, Ireland is out of main lobe, so reception is not stable during the day. Perhaps 1.8m antenna is little bit too small for your location and it does not really matter what LNB is used. Maybe you have some friends around you who has 1.8m antenna? They could check whether they have same difficulties pulling signal.
If you wish to try another LNB on your dish, I have new GI-209P (new, in the box) which I could send to you.
From time to time 2.4m antennas appear on the second-hand market. If you see one, just grab it. This will, for sure be best option for you.

 

[trev1978]

Thanks RimaNTSS

Apologies for my ignorance on this! I has also been a few years since I worked at this so I am a bit rusty! Previously I was just about able to get the SD channels on the nordic beam most of the time. Are the HD channels on a tighter footprint to the SD ones? Where could I get a list of the transponders operating on this beam and how can I tell which ones carry SD signal? - I need an SD signal as my portable meter can only pick up SD.

Thanks,

Trev

 

[RimaNTSS]

@trev1978 Transponders, channels and beams are usually found at KoS or Lyngsat, coverage you can look up at Satbeams.

 

[Captain Jack]

Hi Trev,

Forget the HD channels in Ireland, I can't even receive those in Bristol on the 1.8m Channel Master dish. They are on a different satellite - SES-5 - from the main SD ones and are much weaker. Not to mention the fact that HD channel require a higher signal level than SD ones anyway...

Sorry...

 

[s-band]

They are about 2-3dB above threshold here a bit to the east of London on a 1.5m PF. That ties in with the published footprint. It looks like it drops fast and NI is another 300km, or so, outside the 1.2m contour.

1=11265,H,29990,34,2 ;-63 dBm, 11 dB; 16:24 8/11/2017
2=11265,V,29990,34,2 ;-63 dBm, 10.4 dB; 16:24 8/11/2017
3=11305,H,29990,34,2 ;-62 dBm, 11.3 dB; 16:24 8/11/2017
4=11305,V,29990,34,2 ;-62 dBm, 10.7 dB; 16:24 8/11/2017
5=11345,H,29990,34,2 ;-61 dBm, 10.8 dB; 16:24 8/11/2017
6=11345,V,29990,34,2 ;-62 dBm, 10.1 dB; 16:24 8/11/2017
7=11385,H,29990,34,2 ;-61 dBm, 11.1 dB; 16:24 8/11/2017
8=11385,V,29990,34,2 ;-62 dBm, 10.5 dB; 16:24 8/11/2017

 

[scopus]

Doing OK just outside Stoke on Trent too...Channel master 1.8

 

[Captain Jack]

I must be in some weird null around here... The max I had was just over 6 dB which isn't enough for the HD channels.

 

[trev1978]

Thanks Guys,

I am fairly well through my dish upgrades so all I can do is give it a try and at least I will know- I would always be wondering otherwise! I do have an old Spiderbox HD (which I hope is still working) so if i could get it maxed on the sat I could hook that up inside and check a reading. Are there any SD TP's on SES-5 that I could use on my portable meter? Sorry for my ignorance but i don't know the difference in the designation between SD & HD on the TP list.

In theory I shouldn't have been able to get SD nordic beam. At that time I had got reception reports (I think on a different site) and there was another guy who was about 10 miles from me who claimed he was pulling a strong signal on a 1.2 meter dish. So I always felt my 1.9m prime focus was under performing. The situation is probably different with the new sats but at that time the footprint seemed to be much wider further north than indicated on the official maps.

Thanks

Trev

 

[Channel Hopper]

I must be in some weird null around here... The max I had was just over 6 dB which isn't enough for the HD channels.

Dodgy installer ?

 

[trev1978]

Hi Guys,

On the Invacom adjustable feedhorn instructions (see attached) there is a graph to work out the protrustion of the waveguide beyond the scaler ring. Am I correct in assuming that f/d is the focal length divided by the overall diameter of the dish?

Stupid question I know but i just wanted to check!!

Thanks,

Trev

 

[scopus]

Hi Guys,

On the Invacom adjustable feedhorn instructions (see attached) there is a graph to work out the protrustion of the waveguide beyond the scaler ring. Am I correct in assuming that f/d is the focal length divided by the overall diameter of the dish?

Stupid question I know but i just wanted to check!!

Thanks,

Trev

Not quite Trev, see here....
http://www.titaniumsatellite.com/downloads/Guides/CK1S_LNBF_Install_Guide.pdf

 

[trev1978]

Image 1

 

[trev1978]

Image 2

 

[trev1978]

Image 3

 

[trev1978]

Image 4

 

[scopus]

Image 4

Ahhhh good old unistrut!

 

[trev1978]

Hi All,

I just wanted to give a quick update on how I have been progressing. I have straightened the dish using the structure shown in photo 1 & 2. I had split the dish into 12 segments using fishing line and then used the threaded bar to ease the dish into shape so that all the lines just touched in the centre. I have centred the Invacom feedhorn on the axis of the dish and set it to the calculated focal point and I have maxed out the signal as far as possible using alignment and adjusting the lnb (including skew). I have been maximising it using the SD transponder in image 4. I haven't as yet hooked up the HD machine- but I wouldn't be that confident as I had been hoping to push a higher reading on the above TP.

One questing I have relates to the Invacom adjustable Feedhorn. I did the calculations for the projection required and accurately set it using Vernier callipers. On Saturday, as an experiment, I tried adjusting the corrugated feedhorn as I though it would need 'tuned'. I tried it at half turn intervals. And you know what?- It made zip difference!! I tried the ring right along the threaded section and the signal strength and quality stayed exactly the same. I even tried the ring projecting a few threads beyond the waveguide and again it made no difference. Next I tried the corrugated ring completely off (just leaving the waveguide). In this instance the signal strength stayed the same but the quality dropped by 4%. Does this seem right? I admittedly don’t fully understand the purpose of the corrugated ring but I would have thought that it should have had more of an impact than this- especially as the projection is supposed to be important. Am I missing something?


Thanks Trev

 

[trev1978]

PS This is my calculation for the feedhorn

 

[trev1978]

Ahhhh good old unistrut!

I have a local supplier who had a bundle of old unistrut they are wanting clear off- so got the whole lot free!