Norsat LNB on Mini Bud

[Captain Canuck]

Has anyone experimented with these Norsat LNB's on a 1.2m or 1.8m dish? I'd like to get both Ku & C Band on a smaller dish. I'm restricted to dish size because of my location (and more likely Bylaws). I'm a newbie to all this and am looking for a "turn key"/hassle free solution. From what I've read, the Ku Lnb would be the central lnb and the C Band would be off center. Are the Norsats only meant for a prime focus dish? What kind of feed horn thingies and brackets would I need?

 

[Anole]

bigger is always better:

Has anyone experimented with these Norsat LNB's on a 1.2m or 1.8m dish? I'd like to get both Ku & C Band on a smaller dish. I'm restricted to dish size because of my location (and more likely Bylaws). I'm a newbie to all this and am looking for a "turn key"/hassle free solution. From what I've read, the Ku Lnb would be the central lnb and the C Band would be off center. Are the Norsats only meant for a prime focus dish? What kind of feed horn thingies and brackets would I need?

Your post was moved to a thread of its own.
But it had been on a discussion of dual-output LNBFs like the C2 and DMC242, and how to hook them up.
That thread transitioned into conversation about Norsat LNBs on a an Orthomode feedhorn.
Here is a thread specifically discussing the Ortho feeds, and you should find the info helpful:
Thinking about orthomode feedhorns
For me to repeat anything from either thread, would be redundant at this time.

However, dual band reception on small dishes is quite challenging.
I'd only recommend that you begin thinking 1m for Ku, and 1.8m or larger for C-band.
And, if you'll plan ahead and check the signals you -want-, you can find out now if a given dish size will be satisfactory.

 

[coinmaster32]

Just because its a norsat, doesnt mean its gonna pull it in better. There are 2 factors that determine a lnb's power. The L/O stability, and the degree.

A 80 degree lnb is not going to pull in as strong of a signal as a 15 degree lnb.
Also one that is +- 3.0 mhz is going to have a little more trouble then one that is +-50khz.

Unless you can get a norsat dirt cheap, I would stick to finding a calamp lnb.

 

[pendragon]

Just because its a norsat, doesnt mean its gonna pull it in better. There are 2 factors that determine a lnb's power. The L/O stability, and the degree.

A 80 degree lnb is not going to pull in as strong of a signal as a 15 degree lnb.
Also one that is +- 3.0 mhz is going to have a little more trouble then one that is +-50khz.

Unless you can get a norsat dirt cheap, I would stick to finding a calamp lnb.

This is not correct. The LO stability of a LNB has very little to do with FTA-level performance. Only when a small SR approaches the LO stability will you tend to see problems. Most recent DVB tuners will lock higher SR signals within the LO stability range.

The equivalent noise temperature can have some effect on one's ability to lock a signal. However this effect is often exaggerated and many cheap LNBs/LNBFs do not have accurate ratings (ie. their actual noise temperatures are higher than specified). Quality LNBs such as Norsats and Cal Amps, when not cheap clone knock-offs, are far more reliable in this respect. Quite often a quality LNB will outperform a cheap LNB even when the former has a higher noise temperature.

As we move to 8PSK and higher order modulations in DVB-S2, the phase noise of LNBs starts to have a significant effect on the 'lockability' of a weak signal. While I haven't done a careful study, I have a hunch that the problems some people have with cheap LNBFs may be traceable to poor phase noise performance. Cheap LNBs/LNBFs are rarely well specified with respect to phase noise and this is suspicious. Quality LNBs offer excellent phase noise specs and real-world DVB-S2 performance.

For C-band I use Norsat 8115s and for Ku-band I generally prefer Invacoms. I am experimenting with alternatives to the latter, but with C-band I am perfectly content. The Norsat 8115 has a 150 kHz stability which is of no use for most FTA purposes. I like it so all my C-band dishes track closely, and my spectrum analyzer can read accurate frequencies. Otherwise something like a Norsat 8515 (500 kHz stability) would work as well. I've seen these for about $50 new, which represents about as low as can go to get consistent, high level performance.

With respect to the OP's question, I would absolutely recommend a 1.8m for combined C/Ku reception if you can make it work. I run C-band with four dishes ranging from 1.8 to 3.2m. There are very few signals I cannot lock on the 1.8m and we tend to use it the most. The 1.8m is also the only combo C/Ku dish I run and from experience recommend a dual orthomode feed. The cost of this quickly adds up, but it provides a dramatic performance improvement over anything else, other than a single ortho which only does C-band.

 

[Captain Canuck]

This now requires a rethink. I'm also still playing with Dishpointer (see my newbie post in that forum: "Obstacle Height") but so far things look good for a backyard dish. I'll also have to check out prices of this gear (things are more expensive here in Canada).

A larger dish (say 1.8m)- now prime focus - seems a little more intimidating especially for a newbie when you consider proper dish alignment is ESSENTIAL for one of these babies.

 

[pendragon]

A larger dish (say 1.8m)- now prime focus - seems a little more intimidating especially for a newbie when you consider proper dish alignment is ESSENTIAL for one of these babies.

A larger dish may seem more intimidating and it will require more secure anchoring provisions. However the polar mounts for a 1.8m prime-focus dish are often much simpler to adjust accurately than say a 1.2m offset. For example:

1. Azimuth or true south setting - I can loosen the polar mounts for all my prime-focus dishes without materially affecting the elevation. Rotating the mount on the pole can be done very precisely and I can make scratch marks on the pole as reference points as the adjustment converges. With a motorized offset dish, every time I loosen the motor mount to rotate on the pole, the elevation drops temporarily until I tighten it back up. It's also harder to make reference marks accurately, so a lot of the adjustment is by trial and error.

2. Elevation setting - All of my prime-focus dishes have some sort of threaded rod with nuts to adjust the elevation. This makes fine-tuning child's play as I can make small adjustments by counting fractions of a nut turn. On my motorized offset dish, I have to loosen two bolts, at which point the dish has to be manually suspended because nothing else is preventing it from moving up and down. I have to wrestle the dish to an approximate elevation and tighten the bolts, but it will sag a bit downwards after I let go. If I miss, I get to roll the dice again.

3. Declination adjustment - Most people recommend setting this first and never touching it again. That's good advice because a FTA dish can work reasonably well over a range of declination settings. In fact there is no 'perfect' declination setting, unlike for azimuth and elevation. In this respect it usually doesn't matter how easy or hard this adjustment is because it is normally done just once. Except I'm a perfectionist and I use it sometimes to offset small mechanical errors in the mount, bearings, gravity sag and pole plumbness. Most of my prime-focus dishes also have a threaded rod to adjust this, which makes tweaking simple. My motorized offset also happens to have a threaded rod that accomplishes the same. However this is not the case for many offset dishes, for which adjusting declination is as much fun as elevation.

Because of the above, for me adjusting a prime-focus dish is akin to measuring something accurately with a micrometer, while adjusting a motorized offset is like measuring with a rusted and bent tape measure.

 

[fastscirocco]

With respect to the OP's question, I would absolutely recommend a 1.8m for combined C/Ku reception if you can make it work. I run C-band with four dishes ranging from 1.8 to 3.2m. There are very few signals I cannot lock on the 1.8m and we tend to use it the most. The 1.8m is also the only combo C/Ku dish I run and from experience recommend a dual orthomode feed. The cost of this quickly adds up, but it provides a dramatic performance improvement over anything else, other than a single ortho which only does C-band.

I have a 1.8m (the $69 6 ft special) and have been researching what LNB(s) to use with it;
others have advised using seperate dishes for C and Ku which doesn't make my wife happy.

It sounds like you have had good results using a 1.8m dish; I'd like to learn more.
Where would I acquire a dual orthomode feed, and the proper LNB(s) to use with it?

Thanks
FS

 

[fastscirocco]

Pendragon,

I've done a little research and found this website, I can't recall if we can
post live links so I am not posting them live.

http://www.global-cm.net/feedhorn.html

Manufacturer link here:

http://www.adlfeed.com/

There seems to be a few options, could you provide a little more education/ guidance on which one is best?

Thanks
FS

 

[pendragon]

I've seen dual orthos occasionally below $200, but Nickless-Schirmer (nsccom.com) usually has ADL dual orthos for around $250. Chaparral dual orthos are a bit more but are essentially the same design.

 

[chapelrun]

WOW - that is a great explanation!

This is not correct. The LO stability of a LNB has very little to do with FTA-level performance. Only when a small SR approaches the LO stability will you tend to see problems. Most recent DVB tuners will lock higher SR signals within the LO stability range.

The equivalent noise temperature can have some effect on one's ability to lock a signal. However this effect is often exaggerated and many cheap LNBs/LNBFs do not have accurate ratings (ie. their actual noise temperatures are higher than specified). Quality LNBs such as Norsats and Cal Amps, when not cheap clone knock-offs, are far more reliable in this respect. Quite often a quality LNB will outperform a cheap LNB even when the former has a higher noise temperature.

As we move to 8PSK and higher order modulations in DVB-S2, the phase noise of LNBs starts to have a significant effect on the 'lockability' of a weak signal. While I haven't done a careful study, I have a hunch that the problems some people have with cheap LNBFs may be traceable to poor phase noise performance. Cheap LNBs/LNBFs are rarely well specified with respect to phase noise and this is suspicious. Quality LNBs offer excellent phase noise specs and real-world DVB-S2 performance.

For C-band I use Norsat 8115s and for Ku-band I generally prefer Invacoms. I am experimenting with alternatives to the latter, but with C-band I am perfectly content. The Norsat 8115 has a 150 kHz stability which is of no use for most FTA purposes. I like it so all my C-band dishes track closely, and my spectrum analyzer can read accurate frequencies. Otherwise something like a Norsat 8515 (500 kHz stability) would work as well. I've seen these for about $50 new, which represents about as low as can go to get consistent, high level performance.

With respect to the OP's question, I would absolutely recommend a 1.8m for combined C/Ku reception if you can make it work. I run C-band with four dishes ranging from 1.8 to 3.2m. There are very few signals I cannot lock on the 1.8m and we tend to use it the most. The 1.8m is also the only combo C/Ku dish I run and from experience recommend a dual orthomode feed. The cost of this quickly adds up, but it provides a dramatic performance improvement over anything else, other than a single ortho which only does C-band.

pendragon - - - thanks for the great explanation! Not to get too far off topic but I ordered two Norsat 8700 with a stability of plus or minus 750 kHz - - - both to be installed on a Chaparral Dual Ortho. Should I worry about this stablity number? I do hope to get S2 signals on my 10 foot solid Channel Master.

 

[updatelee]

the lower the SR the more important freq stability is, the higher the order of modulation the more important lower noise is.

If the SR is 30000 then any consumer grade lnb will be just fine. if your looking at an SR of 1000 then ya, freq stability will come more into play.

If your looking at QPSK then a lnb with a noise figure of 0.7db will prob be fine. if your looking at 8psk then you going to want something better, if your looking at 16psk then you might want to look into a higher quality low noise lnb.

 

[pendragon]

Again, if you're concerned about DVB-S2 and particularly being future-proof, look first and compare phase noise specs. These should be specified at several frequency offsets, not just one. The noise figure and/or noise temperature are generally not that important. While they depend on a number of factors, antenna noise temperatures can easily be much larger than those of the LNBs. In such cases LNB noise temperatures and NFs are irrelevant. Frequency stability is usually the least important performance factor, unless you're concerned with very low SRs.

 

[chapelrun]

Specs on the Norsat 8700

Thanks for the answer - - - here are the specs on the Norsat 8700 - - - but I don't know if these are good or bad.

Local Oscillator Phase Noise (Typical) for Norsat 8700

-60 dBc/Hz @ 1 kHz
-80 dBc/Hz @ 10 kHz
-100 dBc/Hz @ 100 kHz


Local Oscillator Phase Noise (Typical) for Norsat 8115

-65 dBc/Hz @ 1 kHz
-80 dBc/Hz @ 10 kHz
-95 dBc/Hz @ 100 kHz

How does this compare with other high quality LNB's?

 

[ACRadio]

For the California Amplifier Extended Professional II 500 Khz stability model 140105-1

-73 dBc/Hz @ 1 KHz
-95 dBc/Hz @ 10 KHz
-110 dBc/Hz @ 100 KHz

 

[pendragon]

All are fine LNBs. You can make a choice mostly on price and availability. I've not found a reliable source for Cal Amps in the year or so - perhaps other can chime in.

 

[Captain Canuck]

So a dual orthomode feedhorn - simply - is a "lens" that you attach both lnb's to & it separates the appropriate wave lengths & directs them to the appropriate lnb's?? I've only seen a picture of the chaparral one ..... is the Bullseye 2 that much better to be 4x more expensive??

 

[ACRadio]

The Bullseye II is made by Chaparral. It is a C/KU dual orthomode using 4 separate LNB's. You must be thinking of seeing the single orthomode C band only Chaparral. The addition of KU is what makes the Bullseye II more expensive.

 

[ParaclipseCKu]

I've seen dual orthos occasionally below $200, but Nickless-Schirmer (nsccom.com) usually has ADL dual orthos for around $250. Chaparral dual orthos are a bit more but are essentially the same design.

Currently $295 for the Chaparral dual ortho from Nickless-Schirmer. Of course that is the Bullseye II!

 

[chapelrun]

I think the Dual Ortho are $65

I may have misunderstood what you stated but that site has the Chaparral Dual Feed feedhorn for $65.

Dual Feed

 

[pendragon]

The $65 feed is a single ortho for C-band only (2 LNBs required). The Chap dual orthos cost $295 and the ADL dual orthos $245 at Nickless Schirmer. These receive both C and Ku band and require two C-band LNBs and two Ku-band LNBs. Both dual orthos perform about the same. The single ortho does a hair better, but of course one loses Ku-band.

One alternative would be to get a prime-focus Ku LNBF or something like an Invacom quad (Linear/Circular or Universal) and couple one of the latter with a feed like Invacom's ADF-120. Sidecar this next to a C-band only, single ortho feed, or better yet, cut out a hole in the C-band scalar through which to mount the Ku feed. This will save some money and might give just a little better C-band performance than a dual ortho. There will be some loss for Ku-band as the feed will be off-axis, but a considerably shorter waveguide will mitigate this effect to some extent. Alignment will be touchy. The dual ortho is a cleaner solution, but will not necessarily perform better.