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.