Best C-band lnbs for offset dishes?
- Thread starter kippysat
- Start date
There are two structural types of LNB(F) for offset dishes.
1. LNBF which has the feed waveguide as part of the barrel, these are generally dual probe for both polarities (simple, easy to use).
2. WR229 flange LNB which has no feed waveguide and attaches to a separate waveguide. These are single probe LNBs for single polarity. Dual polarity is achieved by attaching a pair of them to an OMT.
These are not for dreamers or tyre kickers, some of the higher spec models such as Norsat with 5G filtering can be expensive but they are top of the line.
For testing and a basic introduction, my recommendation would be to buy an LNBF such as a Titanium C138 with 1 cable output or Titanium C238 with 2 cable outputs.
In addition, for an LNBF on an offset dish you will need a hooded scalar. These can be bought separately or sometimes as a kit with the LNBF. The flat scalars used on prime focus dishes are no good for offset dishes.
Lastly, if you are using circularly polarised satellites you will need to use either a dielectric plate in the waveguide feed or use a polo pipe as waveguide feed.
The circular polarity signals need to be converted to linear polarity for the LNB(F) to receive them or there will be signal level reduction. The dielectric plate or polo pipe performs the circular to linear conversion.
1. LNBF which has the feed waveguide as part of the barrel, these are generally dual probe for both polarities (simple, easy to use).
2. WR229 flange LNB which has no feed waveguide and attaches to a separate waveguide. These are single probe LNBs for single polarity. Dual polarity is achieved by attaching a pair of them to an OMT.
These are not for dreamers or tyre kickers, some of the higher spec models such as Norsat with 5G filtering can be expensive but they are top of the line.
For testing and a basic introduction, my recommendation would be to buy an LNBF such as a Titanium C138 with 1 cable output or Titanium C238 with 2 cable outputs.
In addition, for an LNBF on an offset dish you will need a hooded scalar. These can be bought separately or sometimes as a kit with the LNBF. The flat scalars used on prime focus dishes are no good for offset dishes.
Lastly, if you are using circularly polarised satellites you will need to use either a dielectric plate in the waveguide feed or use a polo pipe as waveguide feed.
The circular polarity signals need to be converted to linear polarity for the LNB(F) to receive them or there will be signal level reduction. The dielectric plate or polo pipe performs the circular to linear conversion.
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Hello @moonbase,
Thank you for this information. I've decided to buy an entry level one to start my testing. Seems a sensible
option just in case the signal reception is not what I hoped it would be. I am literally dipping my toes in
the water with C-band.
If the entry level goes well, then I will defo upgrade to the Titanium C138 for improved signal reception.
As soon as it arrives I will be moving the dish to 8W and then 40.5W to see what transponders actually
appear. Will update this thread with my testing results.
Exciting stuff...
Hello All,
This is what arrived in my c-band lnb package. From what little I know, the blue conical ring is designed for an offset dish like mine,
as opposed to the light brownish ring which is designed for a prime focus dish.
There is a small rectangular piece of "tile". I believe this is the dielectric plate and has to be inserted into the lnb if I want to convert
signals to circular left and right and improve the strength of the signals.
I have been reading lots of old threads from @amdade, @empb, @RimaNTSS, @moonbase , @ArloG and others regarding C-band
escapades from 2013 onwards.
Someone referred to another website that has c-band set up information. It said that when setting up the lnb, it is critical that
I insert the dielectric plate at a 45 degree angle to the probes inside the lnb to maximise signal reception.
I know I have a lot of initial work to do to get the lnb to fit on my offset lnb arm, but that is DIY stuff and I am not afraid to do that
work.
May I kindly ask those of you with C-band experience and who have done this before, if I have understood what I read correctly or
should I be doing something else?
Any advice and/or comments on how to do this properly is appreciated? Thank you in advance.
This is what arrived in my c-band lnb package. From what little I know, the blue conical ring is designed for an offset dish like mine,
as opposed to the light brownish ring which is designed for a prime focus dish.
There is a small rectangular piece of "tile". I believe this is the dielectric plate and has to be inserted into the lnb if I want to convert
signals to circular left and right and improve the strength of the signals.
I have been reading lots of old threads from @amdade, @empb, @RimaNTSS, @moonbase , @ArloG and others regarding C-band
escapades from 2013 onwards.
Someone referred to another website that has c-band set up information. It said that when setting up the lnb, it is critical that
I insert the dielectric plate at a 45 degree angle to the probes inside the lnb to maximise signal reception.
I know I have a lot of initial work to do to get the lnb to fit on my offset lnb arm, but that is DIY stuff and I am not afraid to do that
work.
May I kindly ask those of you with C-band experience and who have done this before, if I have understood what I read correctly or
should I be doing something else?
Any advice and/or comments on how to do this properly is appreciated? Thank you in advance.
@kippysat
Yes, you have understood things correctly.
1. Blue hooded scalar for your offset dish.
2. Green rectangular slab is the dielectric plate.
If you look into the barrel of the LNBF you will see the two detector probes, one for horizontal polarity, one for vertical polarity. These probes are at 90 degrees to each other.
If you think of the two probes aligned to a clock face and they are at approximately 10 o'clock and two o'clock respectively, the dielectric plate needs to run vertically between them at 12 0'clock and 6 o'clock.
In other words, the dielectric plate bisects the 90 degree angle between the probes.
Get strapped up and aim for 40.5W or 40.0E, they are both strong satellites with circular polarity, you should easily lock a good few channels.
Once you have bimmed in a few channels check their parameters with Lynsat to be sure you are on the correct satellite.
Use the signal level to peak the dish setup including the position of the hooded scalar along the LNBF barrel. The signal level should change as you move the hooded scalar along the barrel.
You can probably lock channels without the hooded scalar from these two satellites as they have strong signals, then place the scalar on the LNBF and watch the signal level increase by a couple of dB.
Yes, you have understood things correctly.
1. Blue hooded scalar for your offset dish.
2. Green rectangular slab is the dielectric plate.
If you look into the barrel of the LNBF you will see the two detector probes, one for horizontal polarity, one for vertical polarity. These probes are at 90 degrees to each other.
If you think of the two probes aligned to a clock face and they are at approximately 10 o'clock and two o'clock respectively, the dielectric plate needs to run vertically between them at 12 0'clock and 6 o'clock.
In other words, the dielectric plate bisects the 90 degree angle between the probes.
Get strapped up and aim for 40.5W or 40.0E, they are both strong satellites with circular polarity, you should easily lock a good few channels.
Once you have bimmed in a few channels check their parameters with Lynsat to be sure you are on the correct satellite.
Use the signal level to peak the dish setup including the position of the hooded scalar along the LNBF barrel. The signal level should change as you move the hooded scalar along the barrel.
You can probably lock channels without the hooded scalar from these two satellites as they have strong signals, then place the scalar on the LNBF and watch the signal level increase by a couple of dB.
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Thank you @moonbase for the detailed description of the dielectric positioning.
I am going to position it as I have understood the description and then post my picture.
manic01
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Sounds great project, look forward to following your progress.
Here is a pic with the dielectric plate in a 12 o'clock to 6 o'clock position vertically dissecting
the 2 thin probes. It seems to sit roughly 45 degrees between each probe.
One question though....
Do I have to insert the dielectric plate as far as it will go into the lnb or leave it half-way or
very near to the top?
the 2 thin probes. It seems to sit roughly 45 degrees between each probe.
One question though....
Do I have to insert the dielectric plate as far as it will go into the lnb or leave it half-way or
very near to the top?
The dielectric plate is positioned correctly at 45 degrees angle to each probe.
Let the plate go in as deep as it is allowed by the internal side grooves, there should be some type of stop such as the barrel narrowing
If you gonna do it, go in deep, if its deep it must be good.
Don't overthink this, it is simple, it aint rocket science or a gas plant.
Thanks @moonbase. I got it to fit as deep as possible with some effort.
Now, if the weather would just give me a full weekend day without rain, then I
can make some more progress.
To All,
So I tried to get started yesterday evening, however I hit a snag.
On my meter I have to find a way of inputting the transponders to recognise the "L" and "R" polarities.
My issue is that the meter does not provide these polarity options, only "V" and "H".
Now I read somewhere that the meter will still pick up the C-band signal as long as I have input the
correct transponder. However, my issue is....How will I be able to know what "V" or "H" polarity to set for either
the "L" or the "R"?
In other words, does "L" circular left correspond to "H" horizontal or "V" vertical, OR
does "R" circular right correspond to "H" horizontal or "V" vertical?
Once I know what relates to what, then I can set the meter up with a list of transponders and polarities knowing
that I have the correct relationships.
I have tried to describe this as best as I can, so I hope this makes sense?
manic01
Super VIP
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@kippysat
L = H
R = V
It depends on the tuning device if it will display circular polarities as L and R, some receivers only have H and V options but they detect the L/R signals and display them as H/V
Just work on the assumption that L frequencies are detected/displayed as H and R frequencies are detected/displayed as V
Enigma 2 receivers and EBS Pro have the option to display Left/Right polarity wording for the polarities.
Arnoldsat
Registered
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Just to expand on this, if I may, perhaps also for others reading this thread.
The LNB is linear, you can see that by looking at the straight antennas inside it.
The dielectric plate converts circular signals to linear, for the LNB antennas.
Without the dielectric plate the LNB would be set up linear.
That's why it does not really matter if your receiver or meter is indicating H/V and not L/R. The LNB is linear anyway.
This is what a circular antenna looks like:
And you need two of those if you want to receive LHCP and RHCP.
A big satellite dish has more gain. These are two reasons why we work with dish/LNB/dielectric plate
The LNB is linear, you can see that by looking at the straight antennas inside it.
The dielectric plate converts circular signals to linear, for the LNB antennas.
Without the dielectric plate the LNB would be set up linear.
That's why it does not really matter if your receiver or meter is indicating H/V and not L/R. The LNB is linear anyway.
This is what a circular antenna looks like:
And you need two of those if you want to receive LHCP and RHCP.
A big satellite dish has more gain. These are two reasons why we work with dish/LNB/dielectric plate
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- 19
Hi kippysat, i'm usually found on another Uk forum where we have had chats and known as 'john' - nice to see you taking an interest in C band reception and what's involved in setting up etc. I don't want to pittle on yer strawberries & I don't think it's been mentioned yet, but there is a big evil out there that's very important to bare in mind before you start spending time and money. they transmit on the C band frequencies from around 3.6GHz upwards to 3.8Ghz at the moment and they lurk on a cell tower or mini mast possibly very close to your location - they are breeding like rabbits and they go under the name of 5G cell transmissions . For us hobbyist's looking at some fairly weak Cband programming or whatever around the 3.4 to 3.81 GHz area these 5G cell transmissions can be ten to fifteen times greater in strength compared to your weaker Cband channel your trying to watch, and depending on how close you are to a tower etc will and can obliterate your reception even higher up the frequency band way past 3.9~4.0GHz area-they are very destructive to our hobby. If you have a signal meter with a basic spectrum display that can power up your new Cband lnbf that's coming with 18volts there is a simple way to hook the two together with a metre or so of coax and go 5G cell tower hunting. The 5G tx/rx bays on the towers or mini masts are usually the smaller in height ones when compared to the lower frequency 4G tx/rx bays. If you have a 5G tower within 1 mile of you and you are not using any kind of either External 5G filter or a 5G lnbf then you have a battle on your hands. Ideally living out in the sticks see's less of the 5G interference problems. Anyway, good luck with your journey
.
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Thank you for the warning @jaes.Hi kippysat, i'm usually found on another Uk forum where we have had chats and known as 'john' - nice to see you taking an interest in C band reception and what's involved in setting up etc. I don't want to pittle on yer strawberries & I don't think it's been mentioned yet, but there is a big evil out there that's very important to bare in mind before you start spending time and money. they transmit on the C band frequencies from around 3.6GHz upwards to 3.8Ghz at the moment and they lurk on a cell tower or mini mast possibly very close to your location - they are breeding like rabbits and they go under the name of 5G cell transmissions . For us hobbyist's looking at some fairly weak Cband programming or whatever around the 3.4 to 3.81 GHz area these 5G cell transmissions can be ten to fifteen times greater in strength compared to your weaker Cband channel your trying to watch, and depending on how close you are to a tower etc will and can obliterate your reception even higher up the frequency band way past 3.9~4.0GHz area-they are very destructive to our hobby. If you have a signal meter with a basic spectrum display that can power up your new Cband lnbf that's coming with 18volts there is a simple way to hook the two together with a metre or so of coax and go 5G cell tower hunting. The 5G tx/rx bays on the towers or mini masts are usually the smaller in height ones when compared to the lower frequency 4G tx/rx bays. If you have a 5G tower within 1 mile of you and you are not using any kind of either External 5G filter or a 5G lnbf then you have a battle on your hands. Ideally living out in the sticks see's less of the 5G interference problems. Anyway, good luck with your journey
Well, there must be a way of fitting or adapting my LNB to have a 5G filter?
Wouldn't that resolve any interference issues I might face?
PS: How can I tell if my LNB is a 5G lnbf type or possibly already has a 5G filter?
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>> "Well, there must be a way of fitting or adapting my LNB to have a 5G filter?"<< , - to make it easier to give an accurate answer can you post a pic or a link to the exact C band lnb / lnbf you have ordered.
>>"Wouldn't that resolve any interference issues I might face?"<< , - Depends how close you are to the offending tower or in my case, offending 3 or 4 towers. ** That's assuming you have got some 5G towers near you in the first place... hence my suggestion of the signal meter / coax lead / lnbf tip.
>>"PS: How can I tell if my LNB is a 5G lnbf type or possibly already has a 5G filter?"<< , It will usually say so on the box or in it's specs.... post a pic of the unit purchased.
Iv'e spent around two years testing various cheap to high end 5G lnb's and also cheap to high end external 5G add on filters since the evil 5G interference started with me in my area, luckily when 5G started in my area it was way down the frequency range towards the bottom 3.5/3.6GHz area and was from a tower about a mile & a half away , far enough away and down the bottom end of Cband it still gave me reception problems around the 3.5/3.6GHz area but enabled me to still do DX chasing around 3.65GHz upwards. Fast forward up to today, and as mentioned before the towers have multiplied - the nearest one is just under 300mtrs away from me, due South of my 2.2m dish, with one of it's tx/rx panels looking straight at me and has become a major problem.
Hi @jaes,
Please see posts #4 and #8 in this thread for full and clear pictures of my C band LNB and the accessories that came with it.
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Thanks, there is no external design 5G filter as far as i'm aware that fits the circular wave guide tube of a Cband lnbf - internal pcb modification of a Non 5G lnbf is a non starter. Post #5 & 8 pics offer no clue as to whether your purchase has internal 5G filtering.
Please take onboard the seriousness of possible 5G interference within the range of 3.8GHz and down at the moment and risk access prior to progressing .... it has the potential to stop you dead in your tracks