New Lnb changer

[RimaNTSS]

For CM 1,8m I wish to use this retro SMW (big and heavy) LNB, therefore I plan quiet big diameter of circle of centers of LNBs, something about 21cm. But that, of course will be adjustable when needed. One of the important points here, IMHO, is to get lower feedarm at a certain degree to main axis of the antenna or to the surface of the dish. That will help in the future to precisely tune antenna to satellites (if we place digital protractor on the bottom feedarm than we will know exact elevation of the dish). On my drawing I have make this angle 75*.

 

[RimaNTSS]

Made couple of holders adjustable in height. Yes, construction becomes more complex and each LNB should be adjusted individually.

 

[RimaNTSS]

This is my, purely theoretical, drawing of CM 1,8m with lower feedarm and motor behind the dish. As a reference I took biggest LNB I have in stock, if I can manage to place it, than any LNB will be OK for this construction. I think that any Diseqc 1.2 motor 9even the cheapest one) will be able to turn LNBs, as it was originally designed to turn ~1m dish. As I have said before, lower feedarm better to be at certain angle to surface of the dish (in my case it is 75*)., that will greatly help to tune antenna and its polar-mount to the arc. Of course, depending on the used motor it can be placed normal way or upside-down. Thoughts, other opinions, critics are welcome.

 

[Trust]

I made for testing a conicle adaptor with a separation angle of ± 38º and attached the BEST lnb/ Hirschmann feedhorn and a X-1 C lnb with conicle feedhorn to it .
Both lnb's are in optimum receiving position .
Since the construction with the changer motor under the dish and the angled sectors for the lnb's , they pointing together at the backside .
Not a problem yet with those setup but if someone want to use a AV-COM polarizer in combination with other long lnb's , it wont fit .
Also the Inverto KAKUO lnb and the SL3K lnb need a lot of space .
Longer treaded rods aka bigger lnb holder radius could give them more space , but less stable I think .
So maybe we go back to the motor at the end of the feedarm ?
I found a Jaeger DG120 diseqc rotor from them I know they have 360º gear .
Overruled the end switches and driven it by a old Maxdigital SD receiver , it turns and it turns endless , so with modified endswitch , almost 360º mus be possible .
The SG2100 with the modded (360º) gear , turned only 270º with that receiver , so the there is some difference between the motor brands .
The angle between the dish and bottum beam is 73.5º because of the already made conicle adaptor , but if we decide to go on with this system , I can make a new adapter and lower the beam .
Friday tested sevaral lnb / feedhorn combinations at 4.8º E 11.766H .
The big SMW unit with the funny feedhorn 17.7 dB , with the Raven feedhorn 17.0 dB
The BEST twin with the funny horn 16.5 dB with the Raven 17.6 dB and with the Hirschmann feedhorn 17.8 dB
The flanged BlackUltra single with the Raven 15.5 dB
The BEST / Hirschmann comby is now my favorit .

 

[RimaNTSS]

Perhaps we are not so perfect in theoretical (easy algebra, geometry, drawing ... etc.), so slight adjustments for LNB's leaning angle/height are still advisable. And also adjustment closer/further from the dish is needed. Bigger LNB radius might be a problem, but, again, motor was designed to turn the dish and it would be able to turn several LNBs without any play and difficulty, that is IMHO.

The big SMW unit with the funny feedhorn 17.7 dB

That means funny is not always worse!

 

[RimaNTSS]

For this project we need Diseqc 1.2 motor , and I think we should speak here about new motor. Perhaps we can approach this question from 2 directions:
- which motor is better suited?
- what is cheapest motor can be adopted for the mission?
I think that second option is better, as I have said before that any motor would be able to turn LNBs instead of antenna. So there are some options I throw to be considered:
- 41,90
- 28,99
- 35,00
- other chepo

 

[RimaNTSS]

So maybe we go back to the motor at the end of the feedarm ?

Motor in front of the dish makes system more compact and allows to adjust LNBs much easier. But weight weight.... And this weight problem can appear when polar-mount is turned to the end positions. So, perhaps experiment is needed to prove that or to say that everything is fine.

 

[John]

Motor in front of the dish makes system more compact and allows to adjust LNBs much easier. But weight weight.... And this weight problem can appear when polar-mount is turned to the end positions. So, perhaps experiment is needed to prove that or to say that everything is fine.

.. I feel the same about the total boom end weight issue and will definately try and use a counter balance off the rear of the dish and also make sure that the side arms and fixings are really substantial. I'm not too far off fitting the new boom / side arms into place , iv'e already stripped the previous proto-type arrangement off and can soon attach my two C-band units at each side position on the plate to give an indication of the space they take up using a 160mm dia changer plate.

 

[Trust]

For this project we need Diseqc 1.2 motor , and I think we should speak here about new motor. Perhaps we can approach this question from 2 directions:
- which motor is better suited?
- what is cheapest motor can be adopted for the mission?
I think that second option is better, as I have said before that any motor would be able to turn LNBs instead of antenna. So there are some options I throw to be considered:
- 41,90
- 28,99
- 35,00
- other chepo

I prefere a motor with the F conn. downside when the motor is fitted vertical .
But when the motor is at the end of the feedarm , the motor is tilted forward and those connectors are sheltered .
To me , to attach as much as possible lnb's , it should have a 360º gear inside .
Weight issue , a SG2100 - DarkMotor types has a weight of 3.1 kg (incl clamps)
The Technisat ( 28,99 ) claims 1.3 kg , I wonder whats inside , can't find more info (arc reach ?)
Maybe I just order one .

 

[John]

>>> Maybe I just order one .<<<
They are cheap enough, could be worth a punt to satisfy curiousity ;)

 

[Trust]

.. I feel the same about the total boom end weight issue and will definately try and use a counter balance off the rear of the dish and also make sure that the side arms and fixings are really substantial. I'm not too far off fitting the new boom / side arms into place , iv'e already stripped the previous proto-type arrangement off and can soon attach my two C-band units at each side position on the plate to give an indication of the space they take up using a 160mm dia changer plate.

Even with the original feedarms there was a gap of 3 mm between the cross wires (vertical line for horizontal line)
With the changer motor at the front , it was 4 mm , so i used the second groundstand to hold the beam at motor side , loosen the nuts from the sidearms adjuster at dish side so they could move freely for and backwarts . Also loosen the 2 screws at the bottom of the dish were the beam was attached .
Than I straited the dish with the 2 horizontal rods till the gap was gone .
Putting everything back I noticed that the vertical rope was pressing against the horizontal rope , switched there position and shows a gap of 1 mm (vert. behind hor.)
The same phenomenon appeard at my Fibo some time ago and I solved it by making a vertical strut (treaded rod) from the mount to the beam attachment .
Have to make that on this CM too .

 

[Trust]

>>> Maybe I just order one .<<<
They are cheap enough, could be worth a punt to satisfy curiousity ;)

First I gonna mail to Technisat and ask for more info .

 

[RimaNTSS]

I think that lower feedarm should not be connected the bottom of the dish but to the antenna's back plate, something similar how it is done on @Chris1979 antenna. I painted pink piece of metal on the drawing. And also motor can go as much as possible back, again, to work like counterweight.

 

[Trust]

I think that lower feedarm should not be connected the bottom of the dish but to the antenna's back plate, something similar how it is done on @Chris1979 antenna. I painted pink piece of metal on the drawing. And also motor can go as much as possible back, again, to work like counterweight.

For that you will need a solid constuction at the back of the dish meaning more weight at the AZ rotor / mount .

 

[RimaNTSS]

More weight at the mount- make stronger mount (means heavier!)
Speaking about separation between LNBs: If radius of centers on LNBs is about 21 cm than LNBs can be placed with 30* between. Consequently, any motor can be used, even one with only 160* turning.

 

[John]

.. I feel the same about the total boom end weight issue and will definately try and use a counter balance off the rear of the dish and also make sure that the side arms and fixings are really substantial. I'm not too far off fitting the new boom / side arms into place , iv'e already stripped the previous proto-type arrangement off and can soon attach my two C-band units at each side position on the plate to give an indication of the space they take up using a 160mm dia changer plate.

... A bit of a miserable day here with on-off rain periods so not got a lot done.
As i am trying to do this mod using as much of the original CM bits, i'm quite surprised how easy it has been to make the side arms fit without damaging or altering them, although i would prefer to use 8mm rod instead of 6mm adjusters at the dish edge end and then slide some heat shrink over the rod once all adjustments have been made..... this might be altered yet by having it butt jointed to the new inox dish edge bracket and moving the bottom fixing point ... ???.... we will see.

 

[RimaNTSS]

Worked little bit more on plate and made a new struts. 150* turning can easily accommodate 5 LNBs (including C-band)

 

[Trust]

>>> Maybe I just order one .<<<
They are cheap enough, could be worth a punt to satisfy curiousity ;)

Just did ! did not mailed Technisat .
Other issue , how to control the motor ?
Right now I just programmed on a separate receiver 6 channels with different sat positions and select them by hand .
Juras made long time ago the DiSEqC-Converter - Converts DiSEqC 1.0 into DiSEqC 1.2 to control a motor via DiSEqC 1.0
Because Diseqc 1.0 can only handle 4 commands , there will 4 positions , enough for some of us .
With this unit parallel to the lnb switch , the changer could turn automatically .

 

[John]

... A bit of a miserable day here with on-off rain periods so not got a lot done.
As i am trying to do this mod using as much of the original CM bits, i'm quite surprised how easy it has been to make the side arms fit without damaging or altering them, although i would prefer to use 8mm rod instead of 6mm adjusters at the dish edge end and then slide some heat shrink over the rod once all adjustments have been made..... this might be altered yet by having it butt jointed to the new inox dish edge bracket and moving the bottom fixing point ... ???.... we will see.

Decided to go with this configuration in the end .... direct contact of arm with sturdy inox bracket and moved fixing point at lower end up the boom a bit. A lot more sturdy. Everything is just loosely bolted together to ensure good fit of everything , a few nuts and bolts to change for inox etc, excess bolt lengths to cut down ... you get the drift. It's coming on slowly but surely.

 

[John]

Just did ! did not mailed Technisat .
Other issue , how to control the motor ?
Right now I just programmed on a separate receiver 6 channels with different sat positions and select them by hand .
Juras made long time ago the DiSEqC-Converter - Converts DiSEqC 1.0 into DiSEqC 1.2 to control a motor via DiSEqC 1.0
Because Diseqc 1.0 can only handle 4 commands , there will 4 positions , enough for some of us .
With this unit parallel to the lnb switch , the changer could turn automatically .

Scopus Chris put me onto a mini diseqc controller the same as what he uses ..... i might go the same route ?

http://www.juras-projects.org/images/hvusing.png