If you've read part 1, you might like to read Part 2. Oval or round?
What LNB do I need for HD/SD?
What LNB do I need for DiSEqC?
Can I split the feed from one LNB to two tuners?
Universal LNB
Twin-output LNB
Dual or Monobloc LNB
Quad-output LNB
OCTO 8-output LNB
Quattro LNB
What is an LNB?
Low Noise Block-downconverter (so called because it converts a whole band or "block" of frequencies to a lower band).
Also incorrectly known as a "Low Noise Block" or a "Low Noise Blocker"!
An LNB sits on the end of an arm and faces the parabolic reflector ("dish") which focusses the signals from a satellite 24,000 miles away into the "feed horn" of the LNB (see pictures below).
The LNB converts the signals to a lower frequency and sends them out to the cable connector, which you connect to your satellite receiver via coaxial cable.
What is an LNBF?
This is the term for an LNB with an integral feed horn. Nowadays the "F" tends to be omitted.
What is an LNC?
Low Noise Converter. Basically the same thing.
How does an LNB work? Click HERE.
============================
How to test an LNB?
I think my LNB is faulty. How can I test it?
The only way to fully test an LNB is to fit it to a suitably aligned dish and connect a satellite receiver. Then check to make sure every channel is there. If no channels are missing and if it continues to work through a hot day and a cold night, the LNB is fine.
However, if some channels still appear to be missing (with a known good LNB), this could be the fault of the cable (bad connection, water ingress or kinked or wrong type), the receiver or the dish (distorted or misaligned) or local interference (DECT phone, car radar detector, etc.). So then you need to use a process of elimination by swapping the dish, the cable and the receiver (for a different make/model as some receivers won't work correctly with some LNBs). Note that some wall-plate connectors can also cause "channels missing" problems and some electronic devices (DECT 'phone base stations, "Snooper" type radar detectors and microwave ovens) can cause similar problems. I've even had it reported that a bad battery connection in a laptop computer wiped out some channels!
Can't I test it with a meter?
A cheap satfinder meter simply looks at the average strength of all frequencies. It will not tell you if some frequencies are missing. An expensive meter looks at a specific frequency (sometimes more than one) but it will not tell you if some frequencies are missing.
Also, most meters rely on battery power. If the battery can not supply enough current to the LNB, it may give a false reading.
What LNB do I need for HD/SD?
All modern receivers use a "universal" LNB which is compatible with all signals. Make sure that the LNB you choose has sufficient outputs for your receiver(s) which will have one or two inputs each. You can not "split" the LNB cable because each receiver input controls its own LNB output exclusively.
What LNB do I need for DiSEqC?
DiSEqC is a signalling protocol used by some receivers (not Sky) to control an LNB switch or a dish positioner. It is also used by some LNBs which have a built-in DiSEqC switch. This type of LNB is called a "Monobloc" or "Dual-horn" LNB.
Can I split the feed from one LNB to two tuners?
Yes but it won't work properly. You should fit an LNB with more outputs.
Please click HERE for a full explanation.
List of Universal LNB types:
The term "universal" is used to describe an LNB that has "dual band" tuning capability. It came after the "enhanced" LNB which had a slightly extended tuning range and used a 9.75GHz oscillator instead of 10.0GHz. Some people mistakenly think that "universal" refers to "universal fitting", meaning the LNB will fit any dish. There is no such LNB. It's important to choose an LNB which is suitable for your dish and matches your receiver. (All modern "digital" receivers in the UK will work with a "universal" LNB. The same is NOT true for the USA.)
A Universal LNB requires a 22kHz signal at 0.5v p-p to switch its Local Oscillator to 10.6GHz ("high band"). Otherwise it uses its 9.75GHz oscillator ("low band"). Used by ALL modern satellite receivers for Sky, Freesat, FTV and FTA viewing.
Polarisation switching is controlled by dc voltage supplied by the receiver. 12.5v to 14.5v gives vertical and 15.5 to 18v gives horizontal polarisation. A higher voltage than that may damage the LNB but most are OK up to 20v. A voltage that is too low (less than 12.5v) will prevent the LNB from working correctly.
| 
| Typical single-output "Universal" LNB 9.75 and 10.60 GHz L.O. The (obsolete) Cambridge "Platinum"Geo Universal G57" LNB |
Works in 2 bands* 10.7-11.8 and 11.6 - 12.7 GHz. (22 kHz signal switched). Noise Figure usually 1.0 dB or better. Integral feed horn with 40mm neck but C120 flange type available in some models. Spigot fitting for Sky Minidishes.
| 
| "Twin-output" universal LNB
Previously available in Standard (10.0GHz) and Enhanced (9.75GHz) form, but now only in "Universal" form (9.75 + 10.6 GHz), the twin-output LNB provides two outputs to feed two separate receivers for independent working. |
Each output can be switched independently by 13/17 volt input by the individual receiver to change polarisation and by 22kHz to change the band. This type of LNB is sometimes offered with an adapter to fit it to an oval Sky minidish. Beware! It is not designed to focus on an oval dish so its performance when the signal is compromised by bad weather will not be optimal.
"Dual LNB" or "Monobloc LNB"
| 
| Comprises two universal LNBs fixed together at a small angle in a single housing. Only one "F" connector is used. A single coaxial cable connects to the Digital (or Digital + Analogue) receiver which must be able to use DisEqC signalling to select which LNB is to be used. Normally used on an 80cm dish to receive Astra at 19.2'E and Hotbird at 13'E (but not simultaneously). |
monobloc setup monobloc setting up This type of LNB has a single output and the actual satellite signal is selected by the receiver which sends a DisEqC (22kHz) pulsed tone up the LNB cable. So only one satellite transmission can be viewed at a time. This is in contrast with dish systems that have two or more separate LNBs where, with two receivers, both satellite transmissions can be viewed or recorded simultaneously. See picture HERE. Not compatible with a Sky Digibox. Not usually suitable for fitting to a Sky minidish (although it can be done - but expect poor performance in bad weather).
| 
| "Quad-output" or "Quad universal" LNB
This universal LNB can feed four separate receivers. Each receiver has independent control of polarisation and band via 13/17v switching and 22kHz o/off respectively. |
This LNB is used with the new Sky Digiboxes and Freesat receivers that have two LNB inputs and internal Hard Drives for recording a programme while you watch another. Two LNB outputs go to this "Sky Plus" Digibox (or Freesat+) and the other two LNB outputs can go either to two standard Digiboxes or to one other "Sky Plus" (or Freesat+) Digibox. As illustrated, this LNB is not suitable for use with a Sky minidish. The Sky minidish version has a spigot fixing.
| 
| "OCTO" universal LNB
As above but with eight independent outputs.
We stock a Sky minidish "spigot" version and a standard (40mm neck) version. The latter works well with a 60cm dish in the UK. |
|
| "Quattro" universal LNB
This has four fixed outputs and is used only in "head end" I.F. distribution systems (or "multiswitch") for apartment blocks. One LNB supplies a head end unit that can provide (typically) up to 16 outputs for separate Digiboxes. The four outputs of the LNB are as follows:- |
1. Horizontal polarisation low band
2. Horizontal polarisation high band
3. Vertical polarisation low band
4. Vertical polarisation high band
