...I think Invacom created great performing LNBF at the time they came out. I was never a fan of the quality, but in that time and era, they were the best performing LNBF on market. There is a difference between a high quality product and a good performing product. A product can be made of high quality parts, but may not perform as good as a product that is made of lower quality parts. Now you see higher quality LNBFs that also outperform the Invacom...
The implication here is that Invacom LNBs/LNBFs are obsolete and made from lower quality parts, and that WSI branded LNBs/LNBFs are higher quality and outperform the Invacoms. Did I read that correctly?
I can't engage in a quality comparison because I have no data to do a meaningful evaluation. I will say my stable of Invacoms met spec out-of-the box when I got them a few years ago, and they still do today (I have the test equipment).
A lot of people pooh-pooh specs here, but I for one have found Invacom to be honest and complete with their products. Their datasheets contain a number of specs you won't find for other vendor's units. Some of these specs are more indicative of real world performance than what we normally see bandied about. Invacom also provides individual unit calibration curves with their LNBs/LNBFs, a practice not in current fashion with their competitors. Admittedly these curves contain a paltry amount of information, but it does give me a slight comfort they went to the trouble. For the record, the curves that came with my units correspond to my measurements within typical error bars.
Out of curiosity I paper compared two very similar LNBFs: the Invacom QDH-031 and the WSI 534U. Both are quad universal Ku devices. I'm quite familiar with the Invacom but have never tried the WSI. One spec that is often overlooked is phase noise. It's not as important for plain DVB-S, but becomes significant for DVB-S2 8PSK. It is very critical for 16APSK and 32APSK. Most other LNB/LNBF specs pale in significance. These are the Invacom phase noise specs:
-65 dBc/Hz @ 1 kHz
-95 dBc/Hz @ 10 kHz
-110 dBc/Hz @ 100 kHz
My compliments to WSI for listing their phase noise specs; not many vendors do:
-50 dBc/Hz @ 1 kHz
-75 dBc/Hz @ 10 kHz
-95 dBc/Hz @ 100 kHz
Of course one wants the lowest possible phase noise (more negative numbers). The Invacom has 15-20 dB lower phase noise across the board when compared to WSI. From what I can measure, Invacom is telling the truth. I can lock tough DVB-S2 signals very easily with them. I've recently even been having some success with 16APSK and 32APSK.
If the WSI units perform as specified they are decent when compared to non-Invacom units, but they are not anywhere close to being top-of-the-line. I suppose the WSI devices might be conservatively spec'ed, but 15-20 dB does stretch credibility for such an argument. In the worlds I've lived in, this would suggest they know by design they can meet that spec with every unit, but the unit to unit variations could be substantial.
I'm sticking with Invacom for critical applications until I find something that clearly outperforms their products. If the WSI units were within a few dB, I'd probably try them out because vendor-to-vendor measurement practices and calibration accuracies could easily account for such differences. But 15-20 dB is a dramatic difference.
