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· Legend
161 Posts
Discussion Starter · #1 ·
Just for curiosity's sake:

I've only seen one SL3 (non SWM), one SL3 SWM, and one SWM8. But the temperatures of operation of the three are quite different. I never detected any heat from the SL3 (non SWM), the SL3 SWM runs a little bit warm and the SWM8 is almost, but not quite, hot. Why is the SWM8 so very warm? Doesn't the heat tend to damage the electronics of the SWM8? If an SL3 SWM can operate so cool, why doesn't a SWM8?

· Super Moderator
12,437 Posts
The SWM8 has to not only power the SWM electronics it has internally, but also provide power to the non-SWM LNB to lock the four interconnects to the four voltage/tone combinations that can be provided (so they are all continuously available at the SWM8 inputs).

The SWM LNB has more electronics in it than the non-SWM LNB, which is probably what causes it to be warmer.

Personally, I don't like electronic designs that result in a lot of heat, but more cooling capability means larger devices, more design effort, more (or more costly) components, etc. The existing design obviously works and appears to have satisfactory life, so why spend extra bucks to drop 5 or 10 degrees of operating temperature?

· Mr. FixAnything
27,986 Posts
Because if the SWM8 would be installed outside in CA,AZ,TX for example, the silicon junction would be cooked pretty easy - say current temp is 70 degree Celsius and adding 40-45 degree from environment will bring it close to max value 120 degree.

· Premium Member
41,526 Posts
shaggylive said:
13/18vdc = ka/ku
21vdc = swm3 & swm5
29vdc = swm 8, 16, & (32 i think)

more voltz = more heat :)
Think you might be looking at this backwards.
It's the load that is causing the heat, not the supply voltage.

A SWM8 can be powered with a 21 volt PI, as the load isn't much different than the LNB SWM.

The -16 has twice the load of the SWM8, so gets hotter, as the cooling surface isn't twice as big.

The -32 requires a higher wattage [46w] PI than the -16 [40w] .
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