C-Band LNB's: ZINWELL D21A Dual Pol LNBF Review

Today I will be reviewing a popular C-Band LNB: the Zinwell D21A Dual Porarity LNBF.

In large parts of the World satellite TV is delivered mainly using C-Band, instead of the Ku-Band. C-Band is still very popular in Asia, South America and Africa and requires the use of large antennas, usually bigger than 1 meter (3 feet) minimum. 

A C-Band LNB or LNBF works much the same way as a Ku-Band LNB. However, a C-Band LNB is much bigger (about 3x the size) than an equivalent Ku-Band LNB. This is because C-Band uses a much lower frequency range: 3700-4200Mhz for standard C-Band or 3400-4200Mhz for the extended C-Band. Another difference is that, since the C-Band frequency range is much narrower than the Ku-Band, C-Band LNB's only use one local oscillator instead of two.

Zinwell D21A LNBF sideview. Note the F/D markings.

The sticker on the back reveals the main specs: 3.4-4.2 Ghz (extended C-Band), 15ºK noise and 67 dB gain.

Zinwell D21A C-Band LNBF: 15ºK Noise, 67dB gain.

Like most C-Band LNBF, the Zinwell D21A is sold with a prime focus scalar ring and a depolarizer plate for circular polarity signals. 

Most C-Band LNBF's come with Prime-focus scalar ring and depolarizer plate.

The LNB waveguide (body) as markings and slides along the scalar ring to adjust for different dish F/D ratios.

Zinwell D21A with attached prime-focus scalar ring.

If the LNB is to be installed in an offset dish, a conical scalar feed horn should be used instead for adequate dish illumination.

With offset dishes a conical feed should be used for best performance.

The Zinwell D21A can receive linear (Vertical/Horizontal) polarity or circular polarity (Left Hand/Right Hand) signals. To receive circular polarity signals a depolarizer is inserted on the waveguide in front of the receiving probes. The depolarizer is made of Teflon or fibreglass and it is usually provided when you buy the LNB.

To receive circular polarity signals a depolarizer plate is inserted in the waveguide.

Opening the Zinwell D21A reveals the electronics. The local oscillator is under the metal casing and the adjustment screw indicates it is of the traditional DRO type. Some more recent mass market C-Band LNB designs using a PLL type oscillator are becoming commonly available. To learn about DRO and PLL oscillators please read this article. First stage amplification is done by NE3210S1 (K marking) super low noise HJ FET transistors. 

Zinwell D21A LNB pcb

Performance

The Zinwell D21A Dual Polarity LNBF is a good performer. Very weak low symbol rate signals can take some time to lock, but this is normal. This LNB is marked as having 15ºK noise temperature, but it probably has around 20ºK true noise. There are C-Band LNB's marked as having noise temperatures as low as 12ºK, but this unlikely to be true and just marketing tricks.

Televés Universal Single LNB ref. 7475 & 147160 Review

Today I will be reviewing two single output Universal Lnb's from Televés, the Televés UNI LNB Ref. 7475 and the Televés UNI LNB Ref. 147160. These are Universal LNB's that cover the 10.7-11.7Ghz and 11.7-12.75Ghz Ku bands. They are LNBF's to be used with offset satellite dishes.

Televés is a well known and well regarded manufacturer of receiving and test equipment from Spain. They are probably more known worldwide for their triple boom UHF DAT antennas. Although Televés manufactures many of their products themselves, I believe these LNB's are sourced from the Far East.

This is the LNB (or LNBF) ref. 7475 model in typical Televés orange color.

 

Televés ref. 7475 Universal Single Output LNB.

And here is the Televés ref. 147160 LNB.

Televés ref. 147160 Universal Single Output LNB.

The Televés universal single output LNB ref. 147160 is the same as the ref. 7475 LNB. The only difference is the color (white instead of orange). The label on the 147160 model states the LNB has a consumption of 200mA, but this is wrong! Consumption is 90mA maximum for both models. Both models have a 40mm neck and allow for some adjustment of the focus point on the dish. They come with multilingual installation instructions and spec sheet.

The LNB casing is held with hex screws and is sealed with silicon. Here we can see the usual two local oscillator frequency adjustment screws.

Bellow is a tear-down photo showing the internals of the Televés ref. 7475 LNB. Like most low price LNB's, the first stage amplification uses the common NEC NE3503M04 HJ-FET transistor, identified by the V75 marking. This transistor has an typical NF of 0.45dB @ 12 Ghz. Televés claims an NF (Noise Figure) of 0.5dB for this lnb. 

This is a DRO type lnb, the oscillators use ceramic dielectric elements which are hidden under the pcb. Televés claims a local oscillator stability of +/-2Mhz. This good enough in most cases, but many newer LNB designs use PLL technology instead, which offer improved stability. You can read about PLL and DRO oscillator technologies in my PLL vs DRO LNB article.

Televés claims a maximum phase noise of -75 dBc/Hz @10Khz. This is not a "stellar" value as many LNB's claim -80 dBc/Hz @10Khz. But we know anyone can claim whatever they want and the reality is quite different!

Televés states a typical gain of only 51dB. This is a lower than usual gain. Most lnb's have a minimum gain of 55 dB or more. Probably the gain figure is also wrong. Note: Televés now sell the 7475 LNB with a stated gain of 58 dB.

Voltage regulation, bias, polarization and band switching is done by the big SSOP-20 package UTC L8211L IC.

Build quality is good, but not perfect. In both lnb's solder flux residue can bee seen in the antenna probes solder joints. Although this is unlikely to have a significant impact on performance, no solder flux should remain in the pcb. 

Televés ref. 7475 Universal Single LNB.

And this image shows the internals of the Televés ref. 147160 LNB.

Televés ref. 147160 Universal Single LNB.

As we can see, the Televés ref. 147160 is exactly the same LNB as the Televés ref. 7475.

Tests

The despite the modest specifications, the Televés ref. 7475 and Televés ref. 147160 perform well, not favouring a particular part of the 10.7 to 12.75Ghz Ku band. Despite using traditional DRO technology this LNB has good frequency stability and is adequate for all but the very low symbol rate broadcasts.

Gain is similar to other tested Universal Lnb's, so probably around 57-58 dB, not the claimed low 51 dB.

Televés claim an NF of only 0.5 dB, while most brands claim 0.3 NF, 0.2 NF or even 0.1 NF. As I have written before, it is simply is not possible to reach such low NF values under normal working conditions. The best available transistors have 0.3 dB NF, at best! So, even 0.3 dB NF claims are unreal, and the Televés 0.5 NF claim is much closer to the real NF.

Televés say low NF is not the only important spec in an good LNB, but also how well it copes with a wide range of signal strengths from the satellite and that the Ref. 7475 copes well in such situations. Since reception conditions for a particular satellite vary from country to country (or even inside the same country) and with different size dishes, it is not easy to verify this claim. However, I agree with the statement from Televés stating that low NF is not the only important spec in an good LNB, but also how well it copes with a wide range of signal strengths.

Note: Televés now sells the ref. 7475 LNB with a claimed NF of 0.3 dB.

Download Televés ref. 7475 LNB specifications here (current version).
Download the NEC NE3503M04 N-Channel HJ-FET transistor datasheet here.

Octagon Optima OTLSO PLL Slim Twin Review

In the previous post I reviewed a single output PLL LNB, the Sharp BS1K1EL100A. Today we are going to review a dual output universal PLL LNB, the Octagon Optima OTLSO PLL Slim Twin.

As the name implies, this is an LNB with two outputs, which means you can connect two receivers and tune the same or different transponders on the same or different polarity on the same or different band. This is the LNB type to buy if you want to feed two receivers from a single dish.

The product name says this is a slim LNB. Well, there is nothing particularly slim about this LNB. It uses a standard size feed horn. If you need to place two or more LNB's very closely, it may not be possible with this LNB. To get an idea of what true slim LNB's look like, please take a look at my Inverto Multiconnect LNB solution review.

Dual or twin output LNB's are naturally more complex than single output LNB's. After the low noise amplification stage for both polarities the signal is split and down-converted to individual outputs by two separate mixer, IF amplification and LO circuits. In the following picture one of this circuits is shown, the other one is located below, but the connection to both LNB's is visible. Being a PLL solution, the circuit is very simple with the usual crystal (27Mhz) and IC (RDA3565ES) which incorporates the mixer, IF amplification and  local oscillators. The first stage low noise amplification is done by NE3512S02 HJ-FET transistors which have a NF of 0,35 dB @ 12Ghz. Like most brands, Octagon claims this LNB has a NF of 0.1 dB which simply is impossible to obtain under normal operating conditions. Gain is claimed to be 60-65 dB.

Opening the feed horn I got a bad surprise. As it can be seen in the close-up image, it appears to be oxidation on the signal probes! The tear-down was done with a newly bought LNB shortly after performance tests where carried out. A perfectly sealed LNB should never exhibit signs oxidation. Usually the signal probes are gold coated to prevent any oxidation and signal degradation. After carefully cleaning the probes a new test was carried, but no significant performance difference was observed. This was not unexpected because it is very difficult to measure very small variations of NF.

Tests

The Octagon Optima OTLSO PLL Slim Twin is a good performer. It does not appear to favour a particular part of the Ku band. However, disassembly showed a potential weakness point in the probes. On can only guess if with time this could become a problem.

Sharp BS1K1EL100A PLL LNB Review

The Sharp BS1K1EL100A is a special LNB. Like all universal LNB's, this LNB receives the 10.7-11.7Ghz and 11.7-12.75Ghz Ku bands and looks like a normal single output universal LNB. But inside it hides two characteristics that make this LNB "special". For one thing, this is a PLL LNB. PLL LNB's, as I explained in my previous post, have much higher frequency stability than the more common DRO LNB's. This makes them specially suited to receive low symbol rate transponders. Marketing claims this LNB has an NF of 0.4 dB, 58 dB gain, 25 dB of cross polar discrimination and current consumption between 80-120mA.

To my knowledge this was the first mass market LNB with PLL technology. According to Sharp this is the first LNB in the world with a unique SoC (System on Chip) that integrates in a single IC the mixer, IF, amplification, PLL and LO. Also according to Sharp, this technology allows decreasing the Noise Figure and increasing the Gain linearity. The two local oscillator frequencies needed to receive the full Ku band are generated from a 25Mhz crystal. Inside the IC this 25Mhz frequency is multiplied by 390 (for 9.75Ghz low band) and 424 (for 10.6Ghz high band).

Teardown

This LNB is easy to open. As you can see, it's really small and short. It may be difficult to adjust signal focus on some dishes.

But another difference separates this LNB from the rest. This is due to its unique waveguide geometry. To my knowledge this is also the first universal LNB to use a square waveguide. Until this model came along all universal LNB's have been using a circular waveguide.

Inside the LNB we don't find the common NE3503M04 HJ-FET transistors (typical NF of 0.45dB @ 12 Ghz), but the newer NE3513M04 HJ-FET with practically identical specs. The mixer, IF amplification, PLL and LO IC is marked C520. PCB and component soldering are top quality as is usual with Sharp LNB's.

Tests

This LNB performs well, but apart from the good frequency stability it doesn't really stand out. I noted that it slightly favours reception of the mid to upper part of the Ku band. If you want to receive very weak signals on the lowest frequencies this may not be the best LNB for that purpose, but it's perfectly adequate under "normal" reception conditions. This LNB was sold very cheaply (< 5 Euros). For the price and build quality it's a good LNB.

To learn more about LNB's and PLL technology, please read my previous post on the subject: PLL vs. DRO LNB - Which is better?

PLL vs DRO LNB - Which is better?

LNB's, every satellite TV system uses them. Universal, Ku band, C band, Ka band, single output, dual output, four outputs or even eight outputs, there are lnb's for every need. But essentially, little has changed in lnb technology for almost twenty years. 

One new development has materialized however, the massification of PLL (Phase Locked Loop) oscillator technology. Before we go further let me quickly explain about this oscillator stuff.

LNB's are electronic devices whose purpose is to amplify and convert the extremely weak and extremely high frequency satellite signals into stronger and lower frequency signals capable of being carried over a coaxial cable to the satellite receiver inside your home. To convert a frequency to another frequency an oscillator circuit is required.

Most lnb's use what is called DRO (Dielectric Resonator Oscillator) oscillator technology. And PLL oscillators in lnb's are nothing new, but until about five years ago use of PLL controlled oscillators was restricted to professional use (and expensive) LNB's. This has changed, and now PLL technology can be found on many low cost mass market lnb's. But is it worthwhile? Let's compare both technologies.

DRO technology lnb

Conventional LNB's use dielectric resonator oscillators (DRO) to generate the local oscillator frequencies necessary to down-convert the satellite signal (Ku, Ka or C band) to the IF band used by satellite receivers. These DRO's use pill-like ceramic components glued to the lnb board as part of the oscillator circuit. If the lnb is dual band it will have two DRO's, one for each band. The DRO oscillators are tuned when the lnb is assembled but they are affected by temperature and can drift in frequency. In a mass market lnb, this frequency drift (up or down) can be as high as 3Mhz.

PLL technology lnb

Unlike conventional DRO lnb's, PLL lnb's use a digital (PLL) circuit to generate the local oscillator frequencies needed to down-convert the satellite signal (Ku, Ka or C band) to the IF band. An lnb down-converter PLL circuit is comprised of a chip (IC) and a crystal oscillator. The IC generates the oscillator frequencies from the crystal and then mixes, down-converts and amplifies the resulting IF signal. Commercial mass market PLL lnb's have local oscillator frequency drift from 300Khz to 500Khz.

Benefits of PLL lnb

The main benefits of PLL oscillator technology are frequency accuracy and stability. Since a PLL oscillator is much more accurate than traditional dielectric resonator oscillators (DRO), a receiver connected to an PLL lnb can lock (tune) to a particular signal faster. And while a DRO frequency may drift +/- 3Mhz with temperature, a mass market PLL lnb will usually reduce this drift to a much smaller 300Khz. That's ten times less! 

Local oscillator frequency stability can be an issue when receiving signals. This is specially true when receiving narrow bandwidth low bitrate digital satellite broadcasts. Receivers struggle more to tune (lock) to such transponders, specially ones that use DVB-S2 and low FEC rates. 

For example, assuming your receiver accepts bitrates as low as 1Mbit/s, reliably locking to a 1Mbit bitrate transponder may prove difficult or impossible with a "traditional" DRO lnb. If the receiver is even able to lock to such a signal (probably only after a few good seconds) it will keep loosing signal lock. A PLL lnb will enable the receiver to tune and lock to such a signal reliably, provided the signal is strong enough.

Another benefit of PLL technology is size. Since PLL circuits don't use the relatively big dielectric resonators, the down-conversion circuitry is greatly simplified and much smaller, leading to smaller and lightweight lnb's.

Is it worthwhile to exchange a DRO lnb for a PLL lnb?

It can be, but not always. A PLL lnb is not necessarily better than a DRO Lnb. There are excellent DRO lnb's. You must be aware that other factors besides oscillator stability affect signal quality. For example, it can happen that you install a more stable PLL lnb but its frequency response is not as good as the previous DRO lnb. If you are having trouble receiving low bitrate transponders (like SCPC) then, a PLL lnb could indeed improve reception. However, if all the channels you are interested in are being broadcast in wide bandwidth transponders with high symbol rates (for example 15Mbits or more), then likely little improvement would be gained with a switch to a PLL lnb.

If you would like to share your experience with PLL lnb's please leave a comment!

Inverto Black Multiconnect IDLB-SINL23-MULTI-OPP LNBF Review

The Inverto Black MultiConnect is an universal lnbf built for a special purpose. When you want to receive two or more satellites in close spaced orbital positions using a single dish, this may not be possible with standard lnbf's, because it's impossible to achieve the correct focus point on both lnb's. The Inverto Black MultiConnect is a very slim lnbf that makes this possible.

In this lnb, the standard scalar feedhorn is replaced by a special dielectric feed system less than half the diameter of the typical feedhorn. The smaller feed allows for much closer spacing of the lnb's and the reception of very close orbital positions. For example, reception of both Astra 28,2º East and Arabsat 26º East is possible using a single dish, a standard lnbf and an Inverto Black MultiConnect.

The Inverto Black Multiconnect has a neck with 23mm diameter, but a 23mm to 40mm adapter is provided. The lnb can also be attached to a special sliding lnb holding bracket by its backside.

The special dielectric feedhorn is shown in the image below. It replaces the typical RCA or scalar metal feedhorn, but is much smaller.

The first stage amplification uses the popular NEC NE3503M04 HJ-FET transistor, identified by the V75 marking. This transistor has an typical NF of 0.45dB @ 12 Ghz. Inverto claims an typical NF of 0.2dB and an 0.7dB maximum for this lnb. Voltage regulation, bias, polarization and band switching is done by Li-sion Technology LS7005 IC.

This is a DRO type lnb, the oscillators use ceramic dielectric elements. Note: the pictures are of a used condition (but functional) lnb.

This lnb receives the 10.7-11.7Ghz and 11.7-12.75Ghz bands. Because a dielectric feedhorn is less performant than a metal scalar feedhorn, I was not expecting great results, but I was surprised. The performance penalty is small, this lnb is a good performer!

Note:

Inverto no longer lists this lnb on their website. It appears to have been replaced by a newer but similar item IDLB-SINL24-MULTI-OPP.

Download information about the Inverto MultiConnect system here.
Download the NEC NE3503M04 N-Channel HJ-FET transistor datasheet here.

Inverto Black Ultra IDLB-SINL40-ULTRA-OPP LNBF Review

The Inverto Black Ultra is one of the most popular lnb's on sale. Inverto claims this is a high performance lnb "for superior reception under the edges of the satellite footprint". Results are mixed however, some say it's very good, others say it's not. I bought and tested one and I was not impressed with this lnb.

This lnb has a so called long "neck". This means the lnb has more room for adjustment of the focal plane. This can be useful, because with some dishes or situations the lnbf may need to be placed closer to the dish reflector for a better signal.

The feedhorn is a 4 ring scalar feed instead of the more typical RCA type feed found one most lnbf's.

The first stage amplifier uses the NEC NE3512S02 N-Channel HJ-FET transistor with a typical NF of 0.35dB @ 12Ghz. Voltage regulation, bias, polarization and band switching is done by Li-sion Technology LS7005 IC. Local oscillators are of the DRO type.

I was not impressed with the quality of the soldering and assembly of this lnb. The pcb had visible dust particles. The bottom picture was taken after the pcb was cleaned.

Bottom pcb view. Both probes for vertical and horizontal polarization are visible. The ceramic resonators are glued to the pcb. Note all the scratches and oxidation on the board! This lnb was bought as new and disassembled soon after being tested, so this was very surprising.

As I said, I was not impressed with this Inverto Black Ultra. It costs around 15 Euros, but performance was no better than a good 8 Euro lnb. Performance was best on the higher frequencies and weaker on the lower end of the 10.7-11.7Ghz band. Also, I have never seen a pcb in such bad condition. Since this is a popular lnb model, I wonder if there may be counterfeits of this lnb or maybe Inverto may have outsourced the assembly to some sub-standard company.

Download the Inverto Black Ultra IDLB-SINL40-ULTRA-OPP specification here.

Download NEC NE3512S02 N-Channel HJ-FET transistor datasheet here.

Sharp BS1R6EL100W LNBF Review

This lnb is more than 13 years old but, in my opinion, it's still one of the best commercial universal lnbs ever produced! This lnb receives the Ku bands 10.7-11.7Ghz and 11.7-12.75Ghz.

Like most lnbs, this is an LNBF (lnb+feed) unit, but with one particularity: mechanically it is not a single casting unit like your typical lnbf. Instead, the feedhorn is attached to the lnb by two screws. One of the benefits of this approach is that just by attaching a different feed you can use the lnb with satellite dishes of different f/d ratios without sacrificing performance. And indeed, Sharp sold this lnb with at least to different feedhorns.

The feedhorn is hermetically sealed on the front (with a plastic cap) and in the back (with a thin plastic film). Since the F connector is also sealed, when the feed is attached the electronics are fully protected from the environment.

But, inside the top casing you can also see a pill type humidity absorber.

The lnb uses NEC's NE3210S1 super low noise HJ FET transistor for first stage amplification. This device is identified by the K marking code and has a 0.35 dB typical noise figure at 12Ghz. Sharp spec's this lnb with an 0.4 dB average NF. Despite using DRO oscillators, this lnb has good frequency stability and works well with all but the very lowest symbol rate broadcasts. This lnb has good wideband response and is a good choice for fringe area reception. For example, it would be a good choice for reception of Astra 2 28º E UK beam in fringe footprint areas, where the popular FTA FreeSat service (BBC, ITV, Channel 4, etc) is broadcasted.   

  Bottom pcb view with the two (vertical and horizontal) signal probes.

Lnb housing with sealed F connector output.

Download the Sharp BS1R6EL100W specification sheet here.
Download the NEC NE3210S1 HJ FET transistor datasheet here.

Welcome to LNB Reviews!

Hello and welcome to the LNB Reviews blog!


For many years I have been an avid satellite TV enthusiast and installed many systems for reception of Ku and C band signals. Many of these systems are for reception of weak satellite signals in the edge of reception footprint also called fringe areas. For these fringe area systems the quality of the LNB (low noise block) is specially important. Selection of the best LNB for the job is often difficult given the huge number of products available and the marketing bull$hit going around.


Over time I have bought, tested and inspected many LNB's. Since this may be useful to many, I will be posting reviews of these lnb's. Many are older models not commercially available anymore, but still interesting to peek inside!


I hope you enjoy the LNB Reviews blog!