Antenna motors - power consumption

[jamie1992]

When the power consumption figures for a DiSEqC dish motor are quoted, does these figures include the power drawn by the LNB itself?

eg. A Fortec Star HH42 is quoted as drawing:
50mA (Standby Mode)
200mA(Normal)
350mA (Max.)

But a typical LNB can draw 120mA - leading to a possible total consumption of up to 470mA (one of my receivers is rated at just 400mA maximum).

Also, what is meant by the three modes - standby, normal and max?

Thanks,
Jamie.

 

[Lazarus]

When the power consumption figures for a DiSEqC dish motor are quoted, does these figures include the power drawn by the LNB itself?

eg. A Fortec Star HH42 is quoted as drawing:
50mA (Standby Mode)
200mA(Normal)
350mA (Max.)

But a typical LNB can draw 120mA - leading to a possible total consumption of up to 470mA (one of my receivers is rated at just 400mA maximum).

Also, what is meant by the three modes - standby, normal and max?

Thanks,
Jamie.

No, the quoted power consumption is for the Motor alone.

As for the Motor Modes:

Standby = Powered up but not executing a demand to change position (ie Simply the quiescent consumption of the on-board electronics)

Normal = Moving with 13V supply (ie Vertical TP selected)

Max. = Moving with 18V supply (ie Horizontal TP selected)

Inevitably, as 13/18 V is used for LNB Polarity Switching, there is a concomitant effect upon the voltage presented to the Motor; This becomes obvious in practice as the Motor runs faster when you select a Horizontal TP (Neat trick for getting from far West to far East a tad quicker ........) !!

 

[Lazarus]

Don't worry to much about the current sourcing specified for the Receiver: Motor Duty Cycles are relatively short, so any overloading is short lived and I've never heard of any Box failures resulting from this.

 

[jamie1992]

Thanks for the info, Tivù.

One last question:
In addition to my DiSEqC 1.3 digital receiver, I have an analogue fixed-dish-only receiver which shares the same dish via a manual LNB switch.

I figured I could position the dish using the digital receiver, and then switch over to the analogue one. Would this work? Or would the sudden lack of DiSEqC signals make the motor unit malfunction?

 

[Robbo]

No, it would be OK, the motorised dish would stay where it was. The Diseqc commends are only sent when the receiver needs to change something.


When you switched the digital receiver back in, it would just be the same as it was before you switched it out.


Now, two receivers controlling one motor using a manual switch would cause minor problems.

 

[Turok]

i only know about this,that the combination,staab HH 100/120 motor,and invacom lnbs are not good,it happen to times,that the diseqec motor destroy the lnb,and i was wondering,how this can happen!
in the beginning of the first movment of the motor,and the stop,the voltage,seems to be to high for the incacom lnb,and then,it stop working,also long time ago,with a satscan motor ,and a old grundig twin lnb that take 250 ma i recogneized,that the receiver often swtich off,because the power that the lnb takes was to much for the motor!
mostly cheap receivers,espasaly from head the modell 790,i recogneized,that it can happen,that some lnbs,that taking to much power,will not work ,when the output,of some receivers is not enough and the cable to long,i put the same cable on a other stb and it works,i see this only one time,in combination with an older lnb and head 790

 

[Trust]

I've had the same problem with my Nokia 9500 and Moteck diseqc motor .
Turning on a hor. TP (18 V) especially coming from positions far east or west , did reboot the nokia . (error LNB short)
This kills 2 lnbs , probably tried the nokia during turning to "keep-up" the lnb power but at the moment the motor stops , there is an "overshoot" that kills the connected lnb .

Therefor a made a third connector at the motec , powering the Relais contacts with a separate 15 V power supply .

 

[Turok]

Hello!
looks like,the old lnbs,are more resistent,against,to high voltage,during motor startup,but the need to much power,and the newer one,are more sensitive of high voltage!
but what would be the reason,that only some lnbs,with some stbs combination make problems,
i dont know!

when the power taking,is exactly the same,on the lnb side itsef

 

[Lazarus]

Hello!
looks like,the old lnbs,are more resistent,against,to high voltage,during motor startup,but the need to much power,and the newer one,are more sensitive of high voltage!
but what would be the reason,that only some lnbs,with some stbs combination make problems,
i dont know!

when the power taking,is exactly the same,on the lnb side itsef

Guesswork only: Does the Motor corrupt the steady DC waveform somehow, as it passes through to the LNB? Even if it did, I can't really see how that would be likely to do anything more than perhaps cause a momentary glitch. Curious, this.

 

[Low Profile]

I've often had receivers temporarily trip when powering a motor, lnb and meter (which probably just takes it over the threshold).

 

[Turok]

Hello!
is there a technical solution avalible,like a power blocker ,that only blocks a little bit,between the cable and the lnb,it should not block the complete voltage,like a protection,for over voltage to the lnb,how you would realeized this?

 

[futumsch]

I've never seen any off the shelf inline overvoltage protection other than for lightning protection, but you would need to open up your LNB and put an 18V zener protection circuit in there. You would need to do this after the bias voltage is split off otherwise you could upset the RF performance of your LNB. Unless one is proficient at electronics, it's not worth it.

 

[Trust]

I've never seen any off the shelf inline overvoltage protection other than for lightning protection, but you would need to open up your LNB and put an 18V zener protection circuit in there. You would need to do this after the bias voltage is split off otherwise you could upset the RF performance of your LNB. Unless one is proficient at electronics, it's not worth it.

Seems to me , its easier and better to do that in the motor !! (for future lnb's)

Tonight I'll search for a topic on Sat4all about a lnb power-booster , i know there was a posting long time ago .

 

[Turok]

how about the waterproof,after openend the motor?

 

[Trust]

I didn't seen any diseqc motor yet with a gasket or whatever , the top-part fits tight over the bottom-part

 

[Trust]

Seems to me , its easier and better to do that in the motor !! (for future lnb's)

Tonight I'll search for a topic on Sat4all about a lnb power-booster , i know there was a posting long time ago .

I found the pics on my own drive , didn't build or test it myself .

 

[A Lancashire Lad]

I found the pics on my own drive , didn't build or test it myself .

I came across your thread I know it's old but I thought I'd add my comments. I've been having problems with rotor drive and it's comes up a lot over various forums. I don't believe the current draw figures that the manufactures quote its a bit like car manufactures quoting fuel mileage figures. also frustrated by the speed at which the Disqc rotors operate. Your circuit looks to inject an additional power source on the LNB motor input feed which means you don't need extra cable to the rotor, image to small to see properly. I've been looking at another possible option it would require extra 2 core cable to the motor. most of the rotors I have seen stripped on the internet use a DC motor (I don't think any use stepper motors) and use two relays to switch the dc polarity to the motor. My idea was to use a separate DC power supply to feed the motor, would have to isolate the LNB voltage feed from the relay contacts. You could use a higher voltage so long as the motor was rated at that voltage. Which would increase the rotation speed of the dish and speed would not be dependent on LNB polarity.
Just to say it's only an idea it should work but I've not tried it, I don't have a spare rotor to play with. If you want to try it you do so at your own risk!

 

[Lazarus]

Always select a Horizontally polarised target TP when shifting a DiSEqC motor ...... they chunter round faster at 18 volts.

 

[A Lancashire Lad]

Always select a Horizontally polarised target TP when shifting a DiSEqC motor ...... they chunter round faster at 18 volts.

Thats was what my idea above would overcome. you would remove the motor supply from the LNB feed and feed the motor from a separate power supply so the voltage feed to the motor would not be dependent on 13v or 18v from the receiver, the receiver would still be controlling the motor, but not powering it. The motor would have it's own supply voltage which could be 18v or higher if the motor can take it. I'm trying to find a cheap used rotor to try out my theory.

 

[Lazarus]

Shame you're not nearer as I have an unused one kicking about on the spares bench.

I look forward to the results of your tinkering.