TD88 Multi LNB setup in Helsinki

[timo_w2s]

It seems like every summer I'm changing something but here is my current setup in Helsinki. I swapped my old clear plastic 80cm dish with a Triax TD88 dish and rearranged some of the LNBs. I immediately saw an increase in signal levels over the old setup, especially on horizontal transponders.

LNBs on the TD88 are looking at 28.2°E, 23.5°E, 19.2°E, 13°E and 5°E.
The ex-BSB dish above it is looking at 1°W.
On the other side of the balcony is another clear 80cm looking at a satellite next to Hispasat.
Not pictured is a log periodic antenna for picking up DVB-T/T2 from Estonia and local Finnish channels.

All LNBs connected to a DrHD F15 and a quad on 28.2°E is also connected to a Sky DRX890.

On 28.2°E I can pick up the old satellites Astra 2A and Eutelsat 28A OK but I can't pick up Astra 2F at all and Astra 2E's lower transponders are just about visible during the mornings if it's not raining. On my old dish I couldn't see Astra 2E at all or a number of weaker transponders on Astra 2A and Eutelsat 28A.

 

[Captain Jack]

Hi Timo. Nice work! Would you get more signal from 28.2e with the LNB in focus rather than offset? Also, and this maybe the angle of the pictures or might not be necessary at your location, but, the LNBs seem to be arranged at the same level. I would assume there would be a difference in height between the 5e LNB and the 28.2e one? Or is it pointless doing it because of signal strength from those sats?

 

[timo_w2s]

Hi Timo. Nice work! Would you get more signal from 28.2e with the LNB in focus rather than offset? Also, and this maybe the angle of the pictures or might not be necessary at your location, but, the LNBs seem to be arranged at the same level. I would assume there would be a difference in height between the 5e LNB and the 28.2e one? Or is it pointless doing it because of signal strength from those sats?

Thanks. There's the funny thing with my dish, I think if it's pointing directly at 28°E the dish is too big to see the satellite from the gap on my balcony and it gets obscured by the wall slightly (which is blocking anything east of 31.5°E) but by rotating the dish slightly further west away from the wall I can actually get a tiny bit more signal (about 0.5dB ) as more of the dish is seeing the satellite, even if it is at a slight angle. At least that's my theory. I've spent a lot of time trying to get the best out of it for 28°E. ;)

As the for LNB positions, again, I've experimented with them and they are set up for best reception as far as I can see. It is slightly angled but as I'm located at 25°E longitude I think the dish is almost looking at the highest point in the ark.

 

[archive10]

Very nice installation! And pleasantly enlightened to hear that the all-metal TD works better than the see-through plastic thingy.
And congrats on the improved reception. (Which is of course a nice but not-necessary side effect og getting a bigger dish )
Next (and perhaps only) step up is to retrofit a circular reflector a-la-fibo to get that Gregorian experience?

 

[Captain Jack]

Yeah, that makes sense with the gap. Wasn't sure of your parallel, so I guess 28e is at the top and because the dish is slightly angled, the LNBs appear to be at the same level.

 

[archive10]

Thanks. There's the funny thing with my dish, I think if it's pointing directly at 28°E the dish is too big to see the satellite from the gap on my balcony and it gets obscured by the wall slightly (which is blocking anything east of 31.5°E) but by rotating the dish slightly further west away from the wall I can actually get a tiny bit more signal (about 0.5dB ) as more of the dish is seeing the satellite, even if it is at a slight angle. At least that's my theory. I've spent a lot of time trying to get the best out of it for 28°E. ;)

The following is all speculation, but...

As pointed out in other threads on this very site, the TD dishes+LNBmounts do not illuminate the entire dish surface. As shown with the laser-pen method (accurate or not), the area mainly used for reflection dos not include the "lower sideburns" of the dish. this means that the working area is slightly shifted towards the top of the dish.

Now... if you suspect that the wall is cutting of part of the dish (i.e. right-hand side when viewed facing dish), then perhaps, just perhaps, you'd get a couple more ergs/iotas out of it if you mounted it 90 dgreees skewed, as in pointing out from your balcony....

Maybe it's 2%, and therefore will drown in interference. But who knows - RimaNTSS at least experimented with dishes that turned, as he found some designs worked better in one plane that the other.

Just a thought...

 

[timo_w2s]

Very nice installation! And pleasantly enlightened to hear that the all-metal TD works better than the see-through plastic thingy.
And congrats on the improved reception. (Which is of course a nice but not-necessary side effect og getting a bigger dish )

The vertical signals went up as I would expect with a 79cm to 85cm dish upgrade but the horizontals where always unusally low on the old dish and are now so much better.

Next (and perhaps only) step up is to retrofit a circular reflector a-la-fibo to get that Gregorian experience?

Might be tricky with the multi-LNB setup? If I could fit a Wave Frontier T90 I would but there is just not enough room.

 

[timo_w2s]

This is a picture of the old dish from a few years ago with the sun right behind 28E in the spring. I'd since then moved the dish lower down the pole and shifted the pole closer to the balcony opening. As you can see there isn't much room for a view of 28E from my west facing balcony and I'm not allowed to have it sticking out.

 

[hexah]

It seems like every summer I'm changing something but here is my current setup in Helsinki. I swapped my old clear plastic 80cm dish with a Triax TD88 dish and rearranged some of the LNBs. I immediately saw an increase in signal levels over the old setup, especially on horizontal transponders.

The mesh in those dishes is optimized for the lower frequencies to make it more see through, you might notice it had a clear roll off in the top frequencies.

Not pictured is a log periodic antenna for picking up DVB-T/T2 from Estonia and local Finnish channels.

Thats a great view from the balcony. The height must help with Estonian muxes, I know they use Triax 100s and DIY big beasts to get Finnish channels from Estonia. I don't know if log periodics are becoming more common in Helsinki (the wierd channel allocations in Sweden would make them good there) but if you have seen the dense forests of band III and IV/V in Italy they are being improved with small log periodics taking over everywhere.

 

[satelliteman]

That's a nice set up there ;)

 

[timo_w2s]

The mesh in those dishes is optimized for the lower frequencies to make it more see through, you might notice it had a clear roll off in the top frequencies.

Just going through some of my old reading I've logged and there wasn't anything very dramatic but there might have been a bit of loss at the very top of the band. The most noticeable change when switching dishes was the horizontal polarity which was always weaker on the mesh see through dish.

Thats a great view from the balcony. The height must help with Estonian muxes, I know they use Triax 100s and DIY big beasts to get Finnish channels from Estonia. I don't know if log periodics are becoming more common in Helsinki (the wierd channel allocations in Sweden would make them good there) but if you have seen the dense forests of band III and IV/V in Italy they are being improved with small log periodics taking over everywhere.

The aerial I have is a bit of an overkill for Estonian TV to be honest. I receive it at maximum signal levels on my TM6900 and TV. I can see the top of the Tallinn TV mast on a clear day... On a good day I can also get Latvian muxes. I also have a Y shaped cable hung up by the dish for FM radio reception (the thick concrete walls do a good job of blocking most reception inside!).

There are quite a few log periodics in Finland these days for local channels. They have ones which over all the bands for decent signal areas although many of the band III DVB-T2 signals now come from different locations to the original TV masts so may require an aerial pointing in a different direction.

 

[Captain Jack]

Do you receive any terrestrial TV from Russia? They are still broadcasting in analogue (in SECAM) in VHF (ch 1 to 11) as well as UHF (ch 21 to 68) , so might be worth checking there.

 

[timo_w2s]

Do you receive any terrestrial TV from Russia? They are still broadcasting in analogue (in SECAM) in VHF (ch 1 to 11) as well as UHF (ch 21 to 68) , so might be worth checking there.

I used to receive Russian SECAM channels quite frequently when I had an aerial pointing at Estonia on the top of my parent's house but I've not noticed anything yet from my flat. It's facing west with a lot of concrete to the east so I suspect that's blocking pretty much most of the signals from Russia. I should take a portable TV up on the roof terrace when conditions are favourable though and see if I can get anything.

 

[hexah]

Just going through some of my old reading I've logged and there wasn't anything very dramatic but there might have been a bit of loss at the very top of the band. The most noticeable change when switching dishes was the horizontal polarity which was always weaker on the mesh see through dish.

If it is a diamond shape mesh I wonder if it is due to the lack of metal reflecting the horizontal signal compared to the vertical signal.

There are quite a few log periodics in Finland these days for local channels. They have ones which over all the bands for decent signal areas although many of the band III DVB-T2 signals now come from different locations to the original TV masts so may require an aerial pointing in a different direction.

And the dipsticks in charge of tv broadcasting here want to cut down the UHF band even though there are more transmitters and more relays in a smaller area compared to Finland!

I doubt they would consider Band III when they need more bandwidth even though we have a national allocation.

I used to receive Russian SECAM channels quite frequently when I had an aerial pointing at Estonia on the top of my parent's house but I've not noticed anything yet from my flat. It's facing west with a lot of concrete to the east so I suspect that's blocking pretty much most of the signals from Russia. I should take a portable TV up on the roof terrace when conditions are favourable though and see if I can get anything.

That would be fun.

I thought of DX here in suitable conditions but it is a long shot. I can't remember getting Finland here, but it was hard to tell without getting a test card. Its very likely I did receive it at times as I got SVT and NRK often enough and the aerial was in the right direction. From here Iceland and Spain were easy, Germany, France and Netherlands more typical of DX, and channels using Cyrillic text were less common.

 

[timo_w2s]

If it is a diamond shape mesh I wonder if it is due to the lack of metal reflecting the horizontal signal compared to the vertical signal.

It is indeed diamond shape. I've attached a close-up of the mesh from the old dish.

I thought of DX here in suitable conditions but it is a long shot. I can't remember getting Finland here, but it was hard to tell without getting a test card. Its very likely I did receive it at times as I got SVT and NRK often enough and the aerial was in the right direction. From here Iceland and Spain were easy, Germany, France and Netherlands more typical of DX, and channels using Cyrillic text were less common.

Back in the analogue days there was quite often a Philips pattern test card during the day on YLE TV1 and TV2, and the commercial channel MTV3.

 

[hexah]

That mesh is similar to a very early type of Sly dish which was 90cm on the longest axis and had the deficiencies I have described.

It was soon replaced by a 60cm circular perforated dish (with round perforations) that was itself soon replaced by the oval thing that is everywhere today.