PLL LNBs and power consumption

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Magic Static

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Oct 12, 2010
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In my quest for better equipment I've been considering putting PLL LNBs on my Bullseye II feedhorn. The use of the Bullseye is enabled by using a multiswitch. I'm using the WNC-SWA48 that has been modded to increase voltage to the vertical LNBs. On one setup I have Norsat DRO LNBs, 2x 8115 C-Band and 2x 4106A Ku. The current draw spec on the C-Band LNB is 130ma and the Ku LNB is 120ma for a total draw of 500ma on my switch. The switch has a power supply putting out 1.0amp at 24v DC. The Norsat PLL LNBs consume way more power. C-Band LNB is 330ma and KU is 200ma for a total of 1060ma draw. I'm thinking I might be just over the limit of the switch. The variable is the voltage spec on the LNBs of 15~24 volts. Is the current spec at 15v or 24v? that would change the power consumption in watts quite a bit. Going to PLL LNBs may not be a simple bolt-on operation, ain't it always something?
 
I have that same switch modded for my Norsats. You can replace the power supply to the switch, with a 3.2 amp LAPTOP power supply. Dells are 19.2 volts. You should be able to pick one up just about anywhere. Do NOT get a clone power supply, get an actual DELL branded one. Or a name branded one.

Plus, contact Norsat or your supplier and find out if that high current draw is constant, as I doubt that it is. Either way, the laptop power supply should last a very long time for you.
 
Another thing I have to consider is the amount of heat the switch produces. In the summer time last year I measured a surface temp of 128°F on the switch case. Of course it gets very warm inside the shipping container where the switch is mounted. But I wonder if the switch can take the extra load and survive the heat? More tests and expirementation is needed. :) I love this hobby!!
 
Mount the switch to a heatsink of some sort if you think the heat is an issue. Even a big piece of sheet metal could help draw heat away from the switch.
 
After some shrewd dealing on Ebay I have some PLL LNBs. Measuring the pull on the power supply to the multi-switch I have determined the KU LNBs pull 190ma each and the C-Band 3220 pulls 300ma each. A Total load of 980ma on the 1.0amp rated power supply. Since I only have one 3220 right now the array also has a 5215 DRO on it pulling 150ma. A load of 830ma right now runs the temp up to 113°F on the power supply , 62°F ambient temp. This will be interesting.
 
After some shrewd dealing on Ebay I have some PLL LNBs. Measuring the pull on the power supply to the multi-switch I have determined the KU LNBs pull 190ma each and the C-Band 3220 pulls 300ma each. A Total load of 980ma on the 1.0amp rated power supply. Since I only have one 3220 right now the array also has a 5215 DRO on it pulling 150ma. A load of 830ma right now runs the temp up to 113°F on the power supply , 62°F ambient temp. This will be interesting.

The power supply will fry at those currents, guaranteed. Pick up a laptop power supply, they usually run around 3.2 amps at 19~ volts.

http://www.ebay.com/itm/19-5V-NEW-L...s_Chargers&hash=item4d0957448b#ht_1735wt_1007 $10, brand new and free shipping.

Here's the 90w docking base power supply, for even more current (they are larger) http://www.ebay.com/itm/Power-Suppl...rs_Chargers&hash=item53f7d5b1c4#ht_2201wt_761
 
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I like this one. http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2104225_-1

24Vps.jpg
 
Hi MS :) Just my 2 cents (from an electronics/electrical tech with 30+ year of training & experience) is it isn't good practice to run an electronic device (or any device for that matter) at it's max input voltage for an extended period of time.
You lost me here. Which device were you refering to? Power supply? Switch? The voltage is constant. The amps are the problem. I think the switch will handle the power needs of the LNBs, I just need a bigger power supply(more amps). So it's not running at max output. That said the current PS is running at 83 percent of its rating for the past couple of weeks with no failures noted. But 98 percent is pushing the envelope.
 
You lost me here. Which device were you refering to? Power supply? Switch? The voltage is constant. The amps are the problem. I think the switch will handle the power needs of the LNBs, I just need a bigger power supply(more amps). So it's not running at max output. That said the current PS is running at 83 percent of its rating for the past couple of weeks with no failures noted. But 98 percent is pushing the envelope.

Sorry dumb-ass moment (embarrassed) i thought the power supply was going to be connected to the lnb directly. forgot the switch.
 
OK I understand what you were saying now. Yes you are right, the LNBs wouldn't take running at 25 volts all the time. That is their max voltage rating. But they all have 18 volts to them :)
 
The Heat is On!!

In the voice of Scotty, "She won't take too much more of this Captain" She'll blow any minute now"
Ambient temp 84°F, 830ma load. The switch is at 122°F and the power supply is 151°F.
The final 3220 is on the way :) I've began modifications to the installation to reduce the heat.
 
In the voice of Scotty, "She won't take too much more of this Captain" She'll blow any minute now"
Ambient temp 84°F, 830ma load. The switch is at 122°F and the power supply is 151°F.
The final 3220 is on the way :) I've began modifications to the installation to reduce the heat.

Find a large chunk of metal, and mount the switch on it. Use some heatsink compound between them for good heat transfer. That should help dissipate the heat.
 
Find a large chunk of metal, and mount the switch on it. Use some heatsink compound between them for good heat transfer. That should help dissipate the heat.
Found some aluminum plate. Drilled and tapped some screw holes and mounted it. So far so good.
025.JPG
 
While putting numbers together to determine the power needs of this setup, one thing has become real clear. The power supply that comes with the WNC SWA-48 is a real power hog. Talk about throwin money away! 80+ it isn't for sure. I figured the LNBs to use 19.61 watts, the switch uses 3.91 watts, and the PS uses 11.48 watts Yikes!
 
Added the new power supply today. The old one was keeping up with the four PLL LNBs but was very warm. Everything is cooler now :)
The new PS has a voltage adjustment pot. I was able to adjust the power to 24.00V exactly under load. The temp will be around the upper 80's today, so I'll see how cool it will be.
HTPCmay13 012.JPGNewPS 008.JPG
 
Switch Cover - Project complete

I was looking at an aluminum scrap pile a found a STB cover. It was the pecfect size, I just had to do it. I twas the perfect cover for my multi-switch setup.
:)
 

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