Just Sharing This Modified my CM LNB holder for KU and CBAND

[Terryl]

If that's the case then a dish with a wider horizontal receive beamwidth would work better, here stateside we use dishes with an elliptical receive beamwidth, this gives us the ability to receive 3 or more satellites with one dish, and in most applications 3 LNB's in one package, and in special applications a second LNB located to one side. (dish 1000 package for 110W, 119W and 129W, add on the 118.8W satellite and a second LNB is used)

Trying to get a good signal on a prime focus dish with a round focal point is tough, see if you can get a dish with an elliptical focal point, (an elliptical dish) you will have better luck with satellite signals offset to one side of center.

 

[Trust]

He may have one left at least he had when I last spoke to him a few weeks ago..

Indeed , for one 1.8 CM all the parts are still available , By the lack off new Technirotors I stopped making lnb changers .
Just do small parts

 

[a33]

Why don't you place the lnbs side by side on the horizontal plane?
for a C/Ku satellite you would have two orbital positions on your positioner.
Your antenna follows the polar arc, it will automatically be placed in the correct position on the arc.

Well, of course, the highest point of the arc for the by-rider LNB will not be exactly correct anymore.
But that will be more of a problem, when you are further away from the equator; and hardly a problem when you are near the equator, I think.

A way to level out that effect to both the LNBs, would be to have the highest point of the arc not at the center LNB, but somewhere inbetween between the center LNB and the by-rider LNB.
Or, even better (perfect!) solution: have a rotation device on the pole, to set where the mount sees its 'true south'. But to realise this, is mechanically quite a challenge, I guess.


( By the way: The same 'leveling-out solution' could be chosen for 2 LNBs above each other: not one LNB at the one and only offset angle, and the other LNB off of the proper offset angle; but both LNBs at a compromise position, a little bit off of the proper offset angle of the dish.
And beware of the higher LNB taking some signal away, for the lower LNB.)

Greetz,
A33

 

[Manikm909]

think im gonna use the 12inch jack with my current setup for CBAND and KU
as per original pic...

https://www.satellites.co.uk/forums/attachments/img_5562-jpg.139339/

wont cost me anything except some time.

 

[Trust]

If you use a polarmount at that dish and you want to switch lnb's by putting them above each other and , you must not change the PM elevation but change the declination .
When adjusted the signal on a satelite by changing the elvation of the mount , your dish wont follow the clarckebelt correctly .

 

[dreambox1959]

I have often seen a actuator installed instead of the elevation adjustment, it is a bad way to do it, but it can be easier than modifying the mount.
if you use a positioner like mine, the elevation adjustment is individual to each position, so mounting with superimposed LNB can work.
on the other hand most of the time the mechanical structure means that the race is very short and the precision is not good.
when you want to make a polar mount you have to think of a system where the stroke for the declination is important: the distance between pivot and anchorage of the jack is large enough.

 

[Channel Hopper]

I have installed many small diameter fixed dishes for use on inclined orbit station keeping (Gorizonts), using the actuator to adjust elevation is quite usual and works well enough even though they should be tracking the movement in a figure of eight loop.

If a specific position is marked for the Clarke belt (for example half way out of a two inch travel) then it can always be returned to to keep tracking correct.

 

[zorrin]

Well, of course, the highest point of the arc for the by-rider LNB will not be exactly correct anymore.
But that will be more of a problem, when you are further away from the equator; and hardly a problem when you are near the equator, I think.

A way to level out that effect to both the LNBs, would be to have the highest point of the arc not at the center LNB, but somewhere inbetween between the center LNB and the by-rider LNB.
Or, even better (perfect!) solution: have a rotation device on the pole, to set where the mount sees its 'true south'. But to realise this, is mechanically quite a challenge, I guess.


( By the way: The same 'leveling-out solution' could be chosen for 2 LNBs above each other: not one LNB at the one and only offset angle, and the other LNB off of the proper offset angle; but both LNBs at a compromise position, a little bit off of the proper offset angle of the dish.
And beware of the higher LNB taking some signal away, for the lower LNB.)

Greetz,
A33

Yes it is a compromise story anyway.
I used this system in Mauritius, therefore closer to the equator indeed.
For Europe it may be less perfect but its antenna is 1m80.
In my opinion the simplicity of the system would compensate for the losses especially in Ku (I say that and I am the first to want 12 jacks...)
I believe that @Manikm909 should consider the @dreambox1959 positioner if he wants to play with two jacks or more, it is in my opinion the perfect unexpected toy for our antennas.

 

[zorrin]

think im gonna use the 12inch jack with my current setup for CBAND and KU
as per original pic...

https://www.satellites.co.uk/forums/attachments/img_5562-jpg.139339/

wont cost me anything except some time.

Do you have two DiSEqC positioners?
By doubling the positions of the main positioner for the C/Ku satellites, the second positioner would actually only have 2 positions, one centered on LNB C and one centered on LNB Ku.
I don't know if I'm clear enough...

 

[Manikm909]

Do you have two DiSEqC positioners?
By doubling the positions of the main positioner for the C/Ku satellites, the second positioner would actually only have 2 positions, one centered on LNB C and one centered on LNB Ku.
I don't know if I'm clear enough...

yes that makes perfect sense, and yes i do, i have 2 in use, and 2 spare.
I think im going to go for it - it wont be difficult to put back the PM elevation to keep the arc tracking.

 

[zorrin]

yes that makes perfect sense, and yes i do, i have 2 in use, and 2 spare.
I think im going to go for it - it wont be difficult to put back the PM elevation to keep the arc tracking.

As @dreambox1959 points out, the problem is the very short travel with a normal mount.
It's free so why not !

But I continued to think that the LNB C should be at the best focal place instead of the Ku.

 

[suedschwede]

2 V boxes must be used, one controls elevation and the other controls azimuth.
All satellite positions must be saved under the same number on both V-Boxes in order to be able to approach the position of AZ/EL appropriately when selecting via receiver.
On my old system I had up to 4 V boxes in operation at the same time, one for azimuth, one for elevation, one for the LNB rotor and one for the KU band LNB skew
The 4 V boxes are now history, everything on the new system is controlled with a JPC-Positioner, which is a great relief

 

[zorrin]

2 V boxes must be used, one controls elevation and the other controls azimuth.
All satellite positions must be saved under the same number on both V-Boxes in order to be able to approach the position of AZ/EL appropriately when selecting via receiver.
On my old system I had up to 4 V boxes in operation at the same time, one for azimuth, one for elevation, one for the LNB rotor and one for the KU band LNB skew
The 4 V boxes are now history, everything on the new system is controlled with a JPC-Positioner, which is a great relief

I thought about doing this in 2015.
I had even done in schema



But I said to myself at the time that the losses in each positioner and DiSEqC motor were not great.

 

[RimaNTSS]

I had even done in schema

I've done something like that as well. 2 positioners connected in series, one actuator and one motor from Fibo dish (working as LNB-changer). VIDEO

 

[cardiff]

I have the JPC positioner for 3 years,(first version built by myself) : a single box, a single remote control and more. If you have a problem, it will only come from your Polar mount installation or other H-H motors, and since the firmware has constantly evolved for the better. (as well as update and settings software).

If technically you don't have the possibility to put a super-jack actuator for the declination (which is the most judicious compared to the elevation which goes against the primary settings of a polar-mount.) do it for elevation as a last resort

Cardiff

 

[dreambox1959]

Thank you, friends, for promoting my device.
it occupies my mind when the work on the farm gives me time!!!

 

[Chr0nik]

I'm tempted to do this on my 1.2m CM... would it work?

 

[suedschwede]

I thought about doing this in 2015.
I had even done in schema

View attachment 143753

But I said to myself at the time that the losses in each positioner and DiSEqC motor were not great.

Here is my old Setup from last Year

 

[moonbase]

I'm tempted to do this on my 1.2m CM... would it work?

It should work within the limitation of a 1.2m dish for C-Band.
Some satellites will have frequencies that can be received on a 1.2m dish but you will be missing quite a lot of stuff.

 

[Manikm909]

elevation jack now fitted, and working, its been tedious!!
couldnt get the jack to raise the dish - have had to use counter weights.
i can now raise my dish by 61 counts, from KU band to receive CBAND
tested tonight on 8w - getting 55% signal on TVE Africa - i havent even fine tuned the CBAND lnb / scalar hood yet
then i can go back to KU for 16.2db on KU band on 1w Al Jazeera.
will test 40.5 later.....