After setting up a big dish like the Channel Master 240, the next challenge would be picking up the right electronic components to get the maximum out of the new setup. This is quite difficult since every manufacturer will claim their product is the best and the internet is full of misinformation. For example, many people will tell you that PLL is the technology to go for and that DRO is for losers. Even with the first PLL LNBF - Titanium - we've learnt that this is bullshit. Titanium is one of the worst performing LNBFs I've ever tried. But what about the professional LNBs and their PLL versions? Well, read on...
First, it's important to note that the following results are not 100% accurate due to varios facts:
1) the tests were not done at exactly the same time of the day but within 1 hour, which may still lead to signal fluctuations
2) the feedhorn might not have been adjusted for optimal performance for each LNB separately, although it didn't seem to matter in terms of lockable transponders
3) the DVB card (TBS 5925) and software (CrazyScan) don't return the same results every time the blindscan is run
Despite these limitations, the test demonstrates what transponders are lockable with which LNB and show the huge differences. The SNR values may not be accurate or at their optimal levels but the results are shocking anyway! Please ignore the horizontal polarization shown in the blind scan results. I used horizontal because I wanted to power the LNBs with 18V.
It might also be useful to remind the minimal SNR value for each modulation. I've copied the following table from satbroadcasts.com.
Good tuners will usually lock with high BER at around 0.3dB below these levels.
Times are not good for DXers with most broadcasts being 8PSK with FEC 5/6, resulting in the need for at least 9.4dB. Even FEC 9/10 can be encountered.
Even before I owned the dish, I have ordered a pair of Norsat 3220 PLL 20°K LNBs, thinking I couldn't go wrong. But as soon as I installed the units, disappointment started to sink in. No matter how hard I tried, I just couldn't lock many transponders at 43°W with this LNB. The result below shows the horrible blind scan result. I tried both LNBs, both performing quite poorly. The only good result is locking 3744V at 9dB.
Alright, so this was a no go. Next up was the 3220's cheaper sibling, 8530 DRO, rated at awful 30°K. I have only one of these and I only tested vertical polarization, which is my favorite. The results were somewhat better, despite the higher K number. But still, I couldn't be satisfied with such mediocre result, right? I still don't see the Playboy HD transponder locked! Interestingly the Televisa feed at 3854V showed quite good signal strength even with this shitty LNB.
Approximately 300 Euro poorer, next up for the test was a pair of California Amplifier Extended Professional 17°K LNBs. The results with these were pretty good, locking additional transponders, although many of those right on the edge or slightly below it (3717V, 4075V).
Now I was 500 Euro down but finally I thought it's starting to pay off. I finally saw the potential of a 2.4m dish in its full strength. However, the improving pattern prevented me from stopping the insane spending spree. Couple of Astrotel's were on its way from the Philippines next. When the package crossed border, DHL charged me an exuberant amount for customs processing and I almost declined to receive the package but in the end I succumbed and paid . In the end those two Astrotels cost me 250 Euros after adding local taxes and DHL fees. But I didn't regret this purchase after trying out these little amazing LNBs. The 15°K rating really seemed to improve the signal on the most fragile transponders. And thanks to the small dimensions and lightweight contruction, the Astrotels immediately became my favorites.
After this, I promised myself that this is it. No more tests, I'm settled with Astrotel Precision 15°K. But then I found this relatively cheap Norsat 8115 up for sale. Only 100 Euro including shipping and taxes. Who could resist. This LNB is used by many DXers and it's obvious why - the results are acceptable and it can be bought quite cheap. It's not better than Astrotel, not even as good, but still good. The major downside is that it's heavier and bulkier.
I wondered whether it could be the Av-Comm OMT used influencing the signal so much so I've tried a classic Titanium PLL LNBF but with disappointing results, as you can see below.
What I've concluded from this test is this:
1) PLL is crap
2) Temperature matters. The 17°K LNBs outperformed a 30°K LNB and the 15°K LNBs outperformed the 17°K LNBs. With these professional LNBs, the noise temperature seems to be the real thing. Now I'm wondering if a 13°K LNB would be even better. Although I'm a bit skeptical, simply because Norsat don't make any 13°K LNBs.
850 Euro spent, champion LNBs found. And now I must stop thinking about the fact that for these extra 850 Euro or even less, I could have had a 3.7m dish and not worry about LNBs at all. In the end, I'd just like to say I have 5 C-Band LNBs for sale! 2x Norsat 3220, 2x California Amplifier and 1x Norsat 8530 :)
And the winner is...