Flipping the servo

[i4tas]

To flip the polarity of a satellite the servo needs to be rotated 90 degrees. Is there a device that can do this via the coax?

Does such a servo exist where it has a "coax from receiver" in and the a "coax out to lnb"?

Or is there a device that I can add in to adapt for this?

 

[truckracer]

An lnbf does this with voltage. Your feedhorn servo won't work like that. You need an analog receiver to run the servo. Or an older Pansat 2500 free to air receiver. Those have servo controls.

I wish DMS international would add a servo feature to the v-box.. This would bridge the gap between old school big dish and moder FTA receivers.

The servo motors are controlled by a +5V Dc feedback pulse. The "pulsewidth" decides how far the probe moves. I saw a website where a guy had built a box that would take 13V or 18V from the coax line and move the servo. He used some type of 555 chip with a crystal and created a pulse generator based on 5v.

I never could get the schematics. If I could have I would have built one and used it here.

 

[i4tas]

well i guess I have to get a lnbf combo insteed of the corotor.

I am unhappy with my 621 so I might get the yuri c / ku as it need no servo.

Having the vbox and a new receiver I want to be able to shedule recordings and have a very automated system and a system where other people in the house can use with one remote. Flipping the polarities is too much of a hassel and won't work for recordings.

I guess they never mass produced this idea, I wonder if that guy was successful in his creation.

 

[Anole]

solutions

I've never seen any specs on how to drive the servo.
Give me some pre-screened links that describe the hardware, and we'll talk.

What is: "yuri c / ku" ?

And what is wrong with a dual LNB C-band feedhorn.?
I just did some research, and found 'em for $65..$75 - Chaparral brand!
That feed, two C- LNBs, a 4x4 multiswitch, and you're good to go.

For those who -must- have both bands:
The dual (quad, actually) C and Ku horns were down in the $350 range for a Chaparral BullsEye II, or $210 for the ADL brand.
I don't know whether the term "orthomode" applies to the C-only, or the C/Ku only, or both, but that's what the Bullseye II is.

So, back to what it takes to drive the servo . . . -

 

[i4tas]

And what is wrong with a dual LNB C-band feedhorn.?

I want ku and c-band, and the bullseye is still a little to pricey right now for me.

What is: "yuri c / ku" ?

http://www.satelliteguys.us/c-band-satellite-discussion/92536-new-yuri-c-ku-lnb.html

 

[voomvoom]

Ok, you sat guys have peaked my interest, just what does orthomode mean? With a Google Search and from Wikipedia, I found this:
Orthomode transducer - Wikipedia, the free encyclopedia

Interesting, to say the least........
Hope it helps.....

 

[Anole]

Okay, I did a little digging on the Yuri.
It was discussed two years ago on the Aussie Vetrun forum!
Was about $95, then. (probably 95 AU $)
Think it was made in China, but the Vetrun guys were all giggly about having one of their own selling it locally.

Since it has only a single output for each band (and you can bypass and disregard it's built-in diseqc switch) it's only claim to fame over a BSC-621 or CK-1, is that the focal plane for both bands is the same (or perhaps individually adjustable).
And of course, you have to move your dish to switch bands on a given bird.

If single output per band and moving the dish are both acceptable, then I think I'd mount this $20 prime focus Ku onto a single or dual output C-band LNB. ($35/40 respectively)

So anyway, find me a description of this servo motor mover, and maybe we can reverse engineer it.
I can't imagine it's too complicated.

 

[i4tas]

Okay, I did a little digging on the Yuri.
It was discussed two years ago on the Aussie Vetrun forum!
Was about $95, then. (probably 95 AU $)
Think it was made in China, but the Vetrun guys were all giggly about having one of their own selling it locally.

Since it has only a single output for each band (and you can bypass and disregard it's built-in diseqc switch) it's only claim to fame over a BSC-621 or CK-1, is that the focal plane for both bands is the same (or perhaps individually adjustable).
And of course, you have to move your dish to switch bands on a given bird.

If single output per band and moving the dish are both acceptable, then I think I'd mount this $20 prime focus Ku onto a single or dual output C-band LNB. ($35/40 respectively)

So anyway, find me a description of this servo motor mover, and maybe we can reverse engineer it.
I can't imagine it's too complicated.

did you see this? this is what truckracer was talking about.

http://www.satelliteguys.us/c-band-...129834-voltage-switched-servo-controller.html

I really don't know much more about this idea, otherthan it should be possible. It wouldn't have to draw the power from the coax, just take the volatage controled pulses and know when to flip the servo.

 

[Anole]

living in a vacuum

Oh, yea. I remember that post by TruckRacer.
Looking inside the unit, it appears to use a microcontroller.
Also, ya only get to see one side of the board, with little idea what's on the back side.

Truck - PM me the link/forum so I can read the supporting discussion, and I'll see if there's enough info to go on.
Problem with a microcontroller, is re-inventing the wheel. That's a little harder.

And the other post in that thread of the servo controller, is nice, but for another purpose.

 

[linuxman]

I hinted to the Sponsors reading this forum a while back that something of this nature could be incorporated into the VBox/GBox pretty easily.

Those boxes already intercept the commands and voltages from the receiver through the coax to move the dish.

I should be easy enough to capture the voltage change to flip the polarity and add a three wire connector to the back side and divert 5V of power to run to the dish.

The problem of skew could be incorporated into the processor and memory of the *Box and set with the remote for the *Box while watching the meter in the receiver, so the receiver wouldn't have to know how to do that. Then the *Box would just have to remember what skew setting at what position.

It would work out better for them sales wise than the voltage controlled LNBFs, and allow the receiver to get a better signal from a tried and true system.

 

[rv1pop]

Any commercial downlinkers out there that have solutions to this question? I have been out of the loop for 3+ years and all the engineers I used work with were older than me by at least a year or two so they have retired, too. The last time I was at a station and they moved a big dish (8 meter, I think, they were using a digital box. The skew and polarity circuts might be adaptable. So what brand / model is in use for that?

 

[truckracer]

I thought about using one of those "servo tester" tools for RC car servo testing.
Same 5V pulse i think. You just turn the knob and it varies the pulse width moving the servo.

There is a servo tester called Esky. It is digital. about 15.00 dollars I think plus shipping.
It would be a manual way to flip the servo from vertical to horizontal.

 

[Anole]

There is a servo tester called Esky. It is digital. about 15.00 dollars I think plus shipping.
It would be a manual way to flip the servo from vertical to horizontal.

That's a good idea. Give it a try and let us know.

I had a phone conversation with my old TV Engineer buddy.
He's got a 3+ meter dish, a reasonable sized one, and a bunch of other satellite stuff at his new house.
His input was that the pulse train was documented in the manual to a Chaparral RECEIVER from days gone by.

He described it as being very much like the RC model servo pulse train.
Which is to say, you vary the pulse width to move the position of the servo.
I didn't find the specs, but typically the pulse may be every 3..10 ms, and around 1ms wide.
It may vary from around 0.5ms duration to 1.5ms duration, but those numbers are not to be trusted.
Those are just the best I remember from RC models, of several decades ago.

Knowing the actual pulse polarity and range of pulse widths, you could easily make the flipper as described.
Anyone with an Analog, 4DTV, or any of several Pansat models with co-rotor output AND an oscilloscope, could take a few readings and put the question to rest.
Alternately, it may be in one of the manuals in our Manual and Documents section here on the forum.

 

[truckracer]

That would be a good idea to check the pulse width.

I think that ESky digital has an input and will readout the pulsewidth it is receiving from its input terminals

You could connect it to a 4dtv receiver and check the pulse output by adjusting the skew manually and record the readings.

I am sure some of the tech guys here could build the circuit to replicate the pulses for V and H using line voltage from the coax to trigger the proper polarity.

I wish DMS international would have incorporated this feature in the V box. They created 1/2 the solution to running a big dish with diseqc commands. They need to build a skew control function in the v box.

 

[ACRadio]

Folks I know that in my stack of old STV magazines from the 1980's I saw a schematic for a servo controller. Almost all of them used a 555 timer but I can't remember the rest. I went to my moms today and took a quick look but I can't find it. I will keep looking through them and see what I can find. If anyone is interested and is feeling nostalgic I thought it might be neat to scan a couple of the old magazines and make a PDF file for download Iif anyone is interested. I have probably 30 or 40 STV's as well as one Satellite TV magazine from 1983. I also have some Home Satellite TV's and a few Satellite TV Videoworld's.

 

[Anole]

design strategy

ACradio -

I'm sure some scans would be well received.

As for the 555, that was one way I was thinking of making such a device.
Possibly with two knobs, one to set each polarity.
Once it was dialed in , you'd leave the knobs alone.
But, if you had some strange bird that was tilted, you could still manually tune it.
Just remember to return the knobs to their preset/premarked position when done.
The V/H would be taken care of automatically, though.

The other was with a tiny/cheap off the shelf microcontroller.
I'd have two buttons.
One would be to adjust to the right (clockwise), and one would be to adjust to the left (counterclockwise)
In this case, we don't really care which is vertical and which is horizontal.

So then, command a horizontal transponder, and the micro senses 18 volts.
Then, when you press the clockwise/counterclockwise buttons, the pulse width changes and is remembered for whenever you again select horizontal.
This calibrates the horizontal pulse width.

Now, select a vertical transponder.
The micro senses 12 volts on the line, and the right/left buttons work the same as above, with the controller remembering where to set the pulse width any time it senses 12v on the line.
This calibrates the vertical pulse width.


Neither way sounds too difficult - I am far more concerned about tapping the voltage off the coax without interfering with the LNB signal or diseqc commands.
But then, I haven't give the whole project too much thought. -

 

[trinity13]

20+ years ago there used to be a stand alone controller for polarotors.
A wallwart supplied power to the unit (which looked something like the
old Atari 2600 paddle controller).
It had a toggle switch to flip from vert. to horz. and a big wheel/knob for
fine adjustment of the probe.
I had one (long gone).
Just an fyi.

 

[truckracer]

Sounds like we need to resurect some old technology!! LOL

 

[linuxman]

20+ years ago there used to be a stand alone controller for polarotors.
A wallwart supplied power to the unit (which looked something like the
old Atari 2600 paddle controller).
It had a toggle switch to flip from vert. to horz. and a big wheel/knob for
fine adjustment of the probe.
I had one (long gone).
Just an fyi.

Hi Trinity13,

I happened to get my hands on some of the units you described when I bought out an installer in KC a week ago.

I have the instructions on two of the units because they were in the original boxes.

Are these what you are describing?



I would sacrifice one of these babies to one of our manufacturers if they would take the technology and incorporate it into the GBox V3000 EDIT: (Hear that Sadoun!!!!! and SatelliteAV!!!!)

The receiver would not need to know anything about what is going on. The GBox has all the information coming into it.

The new apparatus would need to extract the voltage whether 13 or 18 and flip the servo accordingly, have the remote on the GBox with a function for adjusting the skew with logic to remember the position number which the GBox already knows, and set the polarity and skew (both horizontal and vertical) for the position every time the receiver returns to that position.

A lot of guys would buy such a positioner/servo controller and use tried and true technology already in the field.

 

[truckracer]

Sweet, I wish they would incorporate that feature in the V-box or G-box. It would just complete the bridge from old school big dish to new diseqc/FTA boxes.