Invacom LNB Review

CHARLES EVANS TRIES OUT SOME LNBs WITH STAGGERINGLY LOW NOISE FIGURES

If you want to squeeze the last drop of signal from the weakest satellites when your dish is not quite as big as you might like it to be, or simply want the best available LNB as a replacement or multiple-output upgrade, the lowest noise figure LNB available is a must. Invacom makes LNBs in China and the latest range is available branded with the long time UK favourite Manhattan. These are universal LNBs (i.e. 14/18V polarity switching and 0/22 kHz band switching) - these days the most popular type for motorised antenna as well as fixed dishes - and the range has single, twin, and quad-output versions with a Quattro type for SMATV use. There's also a twin version without a feed horn for mounting to separate a C120 Range on separate feed horn (for a non-standard f/d ratio dish).

They are constructed in solid die cast alloy bodies (which are as waterproof and interference-proof as you can get) with an amber window over the scalar rings type feed horn. The two and four output units use the same case (with unused outputs blanked off).

A dark grey plastic shell covers the 'real' housing and provides the neck for a standard LNB clamp (with skew angle markings). The multiple-output models are quite heavy and may require some extra bracing for dishes with flimsier feed arms.

All models are provided with rubber boots for waterproofing the connections (essential for the quad and Quattro with connectors too close together for easy taping) and for sealing unused outputs too.

What will immediately attract buyers to these LNBs, however, is the claimed noise figure - just 0.3 dB.

This is extraordinarily low. Indeed, these days, many manufacturers are claiming such noise figures, which are quite literally unbelievable. This is a 'typical' figure - not really that meaningful if you want to get scientific - but other manufacturers are also guilty of using this measurement rather than the more useful maximum noise figure.

But perhaps the proof of the LNB pudding is in the receiving, and certainly the Invacom LNBs performed extremely well. It was hard to find a satellite that a reasonable dish could not receive.

Eutelsat W3 was easily picked up with a 60 cm dish in East Anglia in the rain, and signals from 1'W that should really require a 90 cm dish came through loud and clear on a 75 cm antenna.

All types did their best to justify the claimed noise Figure, although the single and twin seemed slightly better than the quad and Quattro - although this is easily put down to the individual models tested.

These LNBs (particularly the twin and the quad) are not cheap, and the 0.3 dB noise figure should perhaps be taken with a pinch of scientific salt. But don't let that put you off a range of LNBs that are well made and able to get the very best from any dish

Note from Martin: reports from customers suggest that the twin- and quad-output versions work well on dishes larger than 1.5 metres but the single- does not! We think this is because the quad-output version has the best cross-polar rejection figure.

Reviewed by WHAT SATELLITE & DIGITAL TV January 2003 page 23 The best UK Digital TV magazine

Version 1.0 updated on March 8, 2003