Very Quiet LNBF's

[dish_in_the_sky]

I don't see them here in the USA, but 0.2 dB typ NF LNBFs are relatively easy to get in Europe (at least based on Google,) and there are two (maybe 3 0.1 dB LNBFs advertised as 0.1 dB NF.

As the LNBF NF and dish size determine the system NF the most, optimizing them yields the best results.


Are these NF's real or are they inflated?

You'll pay dearly to get them here in the US. But if anyone has one, try comparing it with a 0.3 dB Invacom or Xtreme II and post the results here.

For now, my TechSAT 0.3 dB unit will do.

 

[Mr Tony]

Unless it truly has been tested, I question any "low noise" LNB

I tried a .3 a while back and my old ExpressVu .6 worked better

 

[Tron]

I don't see them here in the USA, but 0.2 dB typ NF LNBFs are relatively easy to get in Europe (at least based on Google,) and there are two (maybe 3 0.1 dB LNBFs advertised as 0.1 dB NF.

As the LNBF NF and dish size determine the system NF the most, optimizing them yields the best results.


Are these NF's real or are they inflated?

You'll pay dearly to get them here in the US. But if anyone has one, try comparing it with a 0.3 dB Invacom or Xtreme II and post the results here.

For now, my TechSAT 0.3 dB unit will do.

LNBF noise figures aren't the only factor in determining an LNBF's ability to pull in a strong signal. LNBF L.O. stability is another very important factor that is all too often overlooked. For example, I have a .9 noise factor LNB eek that gives me the same performance for G-10R as my Invacom .3 LNBF. The reason for this is that it features an extremely stable local oscillator. It's a Norsat 11009LA...

 

[dish_in_the_sky]

Good points, all.

I did notice a lack of specs on the 0.1 dB LNBFs, and didn't 1ook hard at the 0.2 dB units.

The Invacom, TechSAT Tracker and Xtreme II LNBF's all apear to have similar LO stability of +/- 1 MHz short-term, +/- 3 MHz over temperature.

The best LO stability I've seen is +/- 500 kHz short-term, +/- 1 MHz over temperature.


Here is a suggestion for improving LO stability: Enclose the LNBF electronics and the feedhorn (except the entrance) in an insulated white plastic housing, then use a small heater (say, a 100W resistor) and thermostat to hold it at 80 deg F. It would regulate the temperature except on hot summer days (like a big "crystal oven.")

A Peltier cooler would be even better, run it at ~ 33 deg F (to minimize thermal noise and not allow freezing) but then special care will be required to prevent condensation, which is not good for electronics or for Ku band reception. A sealed enclosure and regenerateable dessicant are required.
If you have the condensation issue handled well, you could run at -30 deg F for even lower thermal noise by running a 2-stage Peltier cooler.

See the Audine/Genesis 16 CCD astronomical camera websites for some info on handling condensation/freezing on electronics.

 

[Tron]

I think the Norsat 11009LA is rated at +/- 100khz, not the absolute lowest out there but still considerably better than most of the LNBFs floating around the market. The L.O. stability is definitely a factor, as much as noise. I was very surprised, since I was ready to ditch that .9 LNB

 

[crawfrdb]

Has anyone any luck with Extreme IIs? My experience with them has been disappointing. My Invacom has proven much better.

I would like to try those 0.1 and 0.2dB NF feeds but avoid buying universal LNBFs as I don't want to deal with inadvertant LO switching on any configuration I might try in the future.

 

[Mr Tony]

I use an Xtreme II with no issues. thing to remember on these is skew is not stright up and down, Its 90 degrees off (there is a little notch on the LNB and that is 0)

http://www.dmsiusa.com/install.htm

 

[crawfrdb]

Thanks for the feedback.

How do the skew settings in the receiver setup work when adjusting a LNBF manually/mechanically? Is this field best set to zero? My receiver seems to default to 45 everywhere. Should I leave it alone or generally set to zero?

Thanks.

 

[Mr Tony]

the receiver skew in the menus is for a polorotor (the 3 wire way of skewing old C-band LNB's). If you aren't using one that skew is not needed

 

[dish_in_the_sky]

Has anyone seen a 0.3 dB Ku LNBF with +/- 100 kHz LO stability?

I see Norsat 0.7 dB LNB's down to +/- 5 kHz LO stability but nothing better than +/- 1 MHz LO stability at 0.3 dB NF.

LO stability will reduce BER just as low NF will, and low phase noise also helps.

The TechSAT Tracker excels in all but LO stability, where it matches the Invacom units.

An LNBF with identical NF, phase noise to the Invacom and +/- 100 kHz LO stability would probably be an outstanding performer, beating even the Invacom units.

This along with a big dish would be a boon for fringe area satellite reception.

BTW, assume a max LNBF gain of 65 dB and a phase noise of -65dBc. dBc refers to "dB referred to carrier." The carrier is the LO output signal. Assume the LO injection level is -10 dBm. Now the phase noise at the IF output is -75 dBm (assuming 0 dB conversion loss,) and assuming a minimum receiver input of -65 dBm with a satellite signal large enough to get an IF output of -65 dBm, the phase noise is now only 10 dB below the IF signal.

So low phase noise is important too.

 

[PSB]

Invacom are still the BEST LNB's I have used as well as being GOLD SPONSORS here! I also have Norsat LNB's