Quote:
Originally Posted by Whatswrongnow?
If anyone here has tested or can test, and is willing to divulge the results, it will be a big thumbs up from many of us!
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Well, here goes. But you can skip the thumbs -- I only deal in Thanks, Reps, and Starbucks coupons (two cream, no sugar)..... hehehehehe
First,
my setup. I have the "garden-variety" rooftop here -- one D500 with DPPlus on 119/110, and a separate dish with DP Dual on 91, feeding the DPP's LNB IN connector. No motor, no discrete switches. I currently have two downleads running straight to the two tuners on the Elite (separator to come later). Everything is grounded.
And the first disclaimer: electronic devices commonly have a wide variation in current consumption, and I would expect that to be true for LNB's. These numbers are for my specific devices -- your mileage may vary.
For all tests, I measured the current supplied from the STB Tuner 1 connector.
First test I did was with just T1 connected, T2 disconnected. My first surprise was that signal Q was very little affected -- could still get a picture with no trouble. Current was 580 ma for pretty much any combination of settings I could set up. This should be considered typical for a 3-LNB, 1-wire connection. Note that the consumption is 83% of the specified max for the tuner -- a little on the high side, IMO.
For the
second test, I replaced the removed T2 downlead. I hoped that there would be some sharing of the load between the two tuners, and I was not disappointed. The current was either 450 ma or 320, depending on the channel selections. I had really hoped that the current would be halved (which would have been 290 ma) but it was not. And 450 ma puts us at 64% of rated, a much more comfortable number. But here's where the fun begins.
I have reported in other threads that I have noted interaction between the two tuners. Sometimes changing the channel on T2 kills the signal on T1, for example. For the first time tonight, with the current meter hooked up I was not only able to validate this observation, but to define it much more closely. The two different current levels only occur when selecting Port 3 (91W) and represent the two different voltage levels required for selecting the polarization directions on legacy LNB's (which I do not have). This is apparently happening because I needed to select an LNB type of "Single" on Port 3 in my setup because the setting which I thought was most appropriate ("OCS-DP") did not give me Q values on both tuners, even though it is working correctly for 119 and 110 (Ports 1 and 2) on both tuners.
But the thing that blew me away completely while doing tonight's testing was that changing channels on T2 would cause the current (and voltage) levels to change on T1. Now that's not right, no matter what the settings are. I will continue this investigation and report it in a separate thread so as not to clutter this one up too much.
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So far, the best information to come out of this experiment is that the LNB's consume more power than I had thought. My three-LNB setup, if powered from one tuner connector, is just about as much load as the box can realistically handle with a small margin for safety (Premier folks, take special note!!) That's one more reason why adding a fourth LNB (for 82W, for example) is best done with a DPP44 and a power injector. My rooftop stuff consumes about 11-17 watts, which is a big contributor to heat generation in the STB.
The two-tuner power sharing actually works, and I would like to do some more measurements with a separator installed to see if it still happens. (I went to my local dealer today to buy a separator, and he kept telling me that what I really wanted was called a switch -- he had never heard of a separator. Oh well.....)
I sure hope it does, that would mean 3 LNBS (at about 200mA each) could be run by each tuner...let's see, a superdish 121 or 1000.2 on tuner 1 and a dish 500 on tuner 2...YEEH***! 
All my previous experience with electronics and labels has been "accuracy is the law" But these things are not made here in the USA.
if there's a better way, let me in on it.
Re: How many horns can this cow wear? Tuner 1 (700mA) Tuner 2 (700mA)
If I find a 300, I may tangle it up with the 500 (DPP) that I have and go the route you suggested jayjay. Still, I would like to see how many LNBS, could be strapped to that box, witout it choking (Testing the envelope is one of my character flaws).
Linear Mode
