Antenna motors - power consumption

Out of hundreds of motorized installs I have never had an LNB fail due to a motor being in-line, this useing all sorts of different manufactures of motors and LNB combo's.

A properly installed system should not have problems with any standard Diseqc motor with a single LNB attached, I have a motorized setup with the Invacom LNB, and have used it for many years, the only problem I had was when a woodpecker took out the LNB's eye cover looking to stash acorns.(Invacom sent a new LNB at no charge)

If you going to use a motor your receiver must be/should be rated for 500 mA MAX (or more) at the LNB input, one rated for 400 mA could cause long term damage to the internal DC power regulator circuitry used to power the LNB.

Also useing cheap coax with a copper clad center conductor could cause an excessive DC voltage drop at the motor, I always use good quality RG-6 quad coax with a pure copper center conductor, and on some long runs of coax (200 feet or 60 meters) I also use a #12 gauge copper wire as a secondary DC ground return, (the whole system is bonded with this) as with some coax the shield is not that good of a DC path for the return.
 
A Lancashire Lad said:
I've been looking at another possible option it would require extra 2 core cable 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.
Click to expand...

Isn't that exactly what @Trust1 did?
Trust1 said:
Therefor a made a third connector at the motec , powering the Relais contacts with a separate 15 V power supply .
Click to expand...

I guess that way you can use any high voltage you like.

If you don't want to go much higher than 18 volts I've seen two other solutions too in some forum (don't know which; was one of those postings also yours, Trust?)

1. Changing the motor circuit in diseqc-signals-circuit and power circuit; and use external power for the power circuit (so not just the relay contacts, as above, but the whole internal 'power' circuit). Motor modification needed.

2. Splitting (outside of the motor) the receiver signal in 22kHz diseqc signals and 'other'; 'other' going to the LNB, and the 22kHz signals going to motor; with a power inserter on the other motor connection (or mixed with the 22kHz line; no real diofference). No motor modification needed that way. However I've seen that a power inserters sometimes cause trouble, by reasons not yet totally cleared....

greetz,
A33
 
Last edited:
I have found that some FTA receiver's do not like the DC power inserter module in-line with them, I have found in bench testing that some (but not all) DC powered switches with a DC power inserter cause the over all impedance at the tuner to act up, some of the switches used by Dish Network will cause a big problem with FTA receivers, the DP44 switches power inserter will cause the receiver to act up.

The big problem with using a power inserter is with LNB's that use the +18 and +13 volt switching to go between transponders, some DC power inserters supply too much DC voltage (19 to 22 volts DC) this will cause the LNB to be stuck on one set of transponders.

The impedance problems I mentioned caused switching problems between channels due to loss of transponders, some have even caused overheating problems in the tuners DC power supply to the LNB.

Theoretically a two way splitter with a DC power path on one side used in reverse could be tried, the DC power side goes out to the LNB, the power isolated side could go to a DC power inserter to run the motor, this way Diseqc commands to move the motor will go to the motor and any DC voltage switching commands would go to the LNB.

I have never tested this setup and do not have the lab equipment anymore to do so, so it's a try at your own risk.
 
a33 said:
Isn't that exactly what @Trust1 did?


I guess that way you can use any high voltage you like.

If you don't want to go much higher than 18 volts I've seen two other solutions too in some forum (don't know which; was one of those postings also yours, Trust?)

1. Changing the motor circuit in diseqc-signals-circuit and power circuit; and use external power for the power circuit (so not just the relay contacts, as above, but the whole internal 'power' circuit). Motor modification needed.

2. Splitting (outside of the motor) the receiver signal in 22kHz diseqc signals and 'other'; 'other' going to the LNB, and the 22kHz signals going to motor; with a power inserter on the other motor connection (or mixed with the 22kHz line; no real diofference). No motor modification needed that way. However I've seen that a power inserters sometimes cause trouble, by reasons not yet totally cleared....

greetz,
A33
Click to expand...
Have found a circuit diagram which shows the concept.
The left side of the is the motor electronics which is still fed from the Tuner LNB supply.
The right side shows the relays that switch power to the motor this power would normally come from the LNB feed. This circuit has isolated the relay contacts from the LNB feed, the motor is now driven from an interdependent DC power supply. Using an independent power source could allow you to increase the motor voltage which = increased rotational speed how ever it depends on what voltage the motor has been designed to run on.
I cant see how you could inject power into the LNB feed as you still require it to to switch between 13v / 18v.
images
 
A Lancashire Lad said:
I cant see how you could inject power into the LNB feed as you still require it to to switch between 13v / 18v.
Click to expand...

Well, you don't!
You insert power only in the 22kHz line for the motor, after splitting. See my option 2, above.

Greetz,
A33
 
a33 said:
Isn't that exactly what @Trust1 did?
A33
Click to expand...

I dont think so i
a33 said:
Well, you don't!
You insert power only in the 22kHz line for the motor, after splitting. See my option 2, above.

Greetz,
A33
Click to expand...
Sorry which one are we talking about is it this one "Wiring the impossible"?
 
The external power only to the relay contacts, what you wrote in #25, is I believe what @Trust1 did, as mentioned in his post #7.
Why don't you think so?

The extra power inserting in the LNB-line, what you wrote in #25, would be relevant only in (extra) option 2 of my post #22;
however power inserting is NOT in the LNB-line but only in the 22kHz motor-line.

Is this clearing things up?

Greetz,
A33
 
a33 said:
The external power only to the relay contacts, what you wrote in #25, is I believe what @Trust1 did, as mentioned in his post #7.
Why don't you think so?

The extra power inserting in the LNB-line, what you wrote in #25, would be relevant only in (extra) option 2 of my post #22;
however power inserting is NOT in the LNB-line but only in the 22kHz motor-line.

Is this clearing things up?

Greetz,
A33
Click to expand...
DOH! I missed Trust1 first comments was more focused on trying to read his little circuit diagram
Apologizes to Trust1 and A33
 
Back
Top