I have a theory and question....

[TheHamNerd]

OK...now this might be out there, but here it goes.

My GeoSat Pro MicroHD power input on the receiver is 12VDC @ 2000 mA which is 2 Amps. I am not sure, but I think most satellite receivers are 12 VDC power input. So it is basically a 120VAC transformer, to rectify and regulate a steady down to 12VDC output at a given current output.

My theory is this: I have various regulated Ham Radio power supplies, or a couple. I am pretty sure that disect switches, and obviously LNBF's get their power from this same wall transformer through the receiver. So why couldn't I make an adapter, and do away with my factory transformer and adapt the power over to one of my regulated power supplies? It is basically the same thing as the plug-in transformer, but I would have more output current at my fingertips. That way, I don't have to worry about how many birds with LNB's I connect, or switches that are current hungry. Never the less you add a motor to the mix to move a dish. If motors and LNB's are different voltages, then this conversion has to be done inside the receiver through its circuitry, and the input is a constant value @ 12VDC.

I am just trying to think outside the box here. And it makes since to me if it can be done this way.

Any thoughts, or am I off base? Does this make since?

 

[TheHamNerd]

DISEQC switch...errr

 

[Bongu]

Some people power their MicroHD from a vehicle battery or a 12V source such as a solar system. As long as your supply can handle 12VDC 2A for the MicroHD, you are fine.

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[TheHamNerd]

Some people power their MicroHD from a vehicle battery or a 12V source such as a solar system. As long as your supply can handle 12VDC 2A for the MicroHD, you are fine.

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Oh yeah!! I don't think that would be a problem. One power supply is a 35 Amp Astron Linear supply, the other is a Radio Shack 20 Amp Switching supply. I was curious if anyone has ever thought of doing this. I was reading somewhere on a forum...it could have been here...I honestly don't remember, but they were having problems with not being able to supply enough power to their motor, switch, and LNBF's. Someone referred them to a larger wall transformer. Shoot, I was thinking for me this would be a better route if I ever had an issue with not being able to supply enough current from the wall-wort supply.

 

[TheHamNerd]

I also have two 100 amp switching supplies wired in parallel for some radio gear. That is 200 amps total, so there is no shortage of current I was just curious if anyone has done it this way.

 

[Bongu]

Just remember that if you supply more than 2A to the MicroHD, it doesn't mean that the MicroHD will use more. There should be current limiting devices in the MicroHD to prevent damage and protect everything else. I believe the output of the MicroHD is limited to less than 500mA. If I am off, I am sure someone will provide the true spec.

There are advanced options for powering switches and motors separately, and if you are a ham, I don't doubt you are able to do this.

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[TheHamNerd]

The back of the receiver which is the power input specs 12 volt DC @ 2000mA which is 2 Amps. It leads me to believe that the factory supplied transformer is that of a 2 Amp max output. Which is no big deal...I never meant to imply that anything was going to need 35 to 200 amps of power....LOL Gosh! I was just implying that if the need was there for it to draw more and it would exceed the factory 2 Amp supplied transformer, then I would be able to give it more juice as needed. I know the power supplies do NOT force more power than the device needs. That is a reference of max output of the transformer @ 2 Amp = 2000mA supplied by the factory at 12VDC input to the receiver....

 

[TheHamNerd]

I am new to the FTA hobby, and sometimes my thinking gets out of control. LOL I think that some of these LNB's draw around 150 mA, then of you throw a motor in the mix that pulls around 500 mA then your at 650 mA....and if you have more than one dish, or more than one LNB....it just all adds up. I am not to this point yet of adding all this, but just trying to have a plan.

 

[bobsav2001]

If you can get a 5 to 10 amp power supply you will do just great....
This is what i would try.
Good luck

73's Bob VE2 FCZ

 

[Cham]

The uHD would require much less than 2a @ 12vdc, the extra current requirement comes from operating a diseqc motor and LNBFs. Diseqc switches take very little power, maybe 1-2mA. When using a diseqc or 22KHz switch, power is only routed to the used port, so only one LNB(F) is being used at any time.

Also LNBF units require two voltages, 13v for vertical and 18v for horizontal polarities. This has to be supplied by the receiver, but can also be supplied through a powered switch taking the amperage load instead of the receiver. The receiver voltage is only then required for the switch signal to determine polarity.

You can supply 12-18v to a diseqc motor directly to take the load off the receiver either by using a power pass splitter or modifying the motor circuitry. Some of us have done this so the motor runs faster when tuning to vertical transponders. Also more than 18v can be supplied to further speed up the motor but I wouldn't go much higher, could damage the motor.

Otherwise any linear or switching power supply that supplies 10-15vdc will power the uHD. Switching supplies are more efficient and create less heat; I think the power supply supplied is a switching supply but I may be wrong..

 

[Titanium]

Current is like water. It doesn't matter if the reservoir is small or large, water will flow through the pipe at the same rate.

Increasing the available amperage above the amount that the STB draws under a full load will not provide additional output current.

The simplest way to provide additional current is to use a powered switch or a voltage inserter. Example: if you what your motor to move quickly between satellites, use a 18Vdc power inserter inline and do not loop out to power the LNBF(s).

Edit: Posted at same time as Cham. Good explanation!

 

[lost_mesa]

The microHD undoubtedly has some internal circuitry to step up the 12 V DC input to 13/18 volts for the output that runs the LNBs, motor, and switches. It would also add an additional 1/2 volt or so, switched at 22 kHz, for 22 kHz and DiSEqC switches, when needed.

Connecting something like a 5 amp external supply to the receiver isn't going to make this internal voltage step up circuitry handle any more current than it was designed for.

 

[radio]

Agreed on most if not all of the above. Given failure of the original power supply I had on my microHD, and experiencing "less than reliable" results using anything less than a 2-amp supply, yes, you must use minimum 2 amp supply.

The 12-volt receiver unit has to step up that voltage to go to LNB's for reliable switching to work! The previous post is correct, it won't make the switching handle any MORE current than designed-for, but it will ensure there's ENOUGH current for the job. I was sent (free of charge, THANK YOU) a 1.5 amp supply from the new operators of the company selling the microHD, but I'm not even going to attempt it's use. Maybe the "newer" run of them takes 1.5 amps, I don't know, but this is not at all like the original supply I had by appearance or by capacity. I'll wait to find a 2 amp unit at some hamfest, then see if my older microHD operates it's switching normally again. It's okay to provide more, current capacity, the unit will only draw what it needs, but don't "under" power it. When I was testing my unit, we used a bench power supply capable of 5 amps and it worked better than on any under-"amped" wall wart. I have since replaced the microHD for daily use with another receiver but will be updating firmware (I had original) and trying to make it switch properly when I get a 2 amp supply.

 

[jorgek]

I too am a ham and have all kinds of 12 volt power supplies. There is no harm in using a PS rated more than 2 amps but as all have stated the STB is designed to only supply 500ma of current to all the peripherals and thats it no matter how large the PS is rated at. Bonus is the larger rated PS will run cool and be happy.