[mythtv-users] Heat issues with USB ATSC tuners?

[rsh1k]

On Thu, Aug 30, 2012 at 10:12 AM, Devin Heitmueller
<dheitmueller at kernellabs.com> wrote:
> On Thu, Aug 30, 2012 at 2:17 AM, rsh1k <roland.sh1000 at gmail.com> wrote:
>> Can anyone tell me if this high power / high temperature issue is
>> unique to the Hauppauge/Pinnacle designs?   Does anyone have a usb
>> tuner that runs cool?
>
> No, this is common practice.  There is nothing unusual about these
> sticks.  The reality is that it takes a good bit of horsepower, and on
> PCI/PCIe tuners the heat is just as much but it's more dispersed by
> the PCB acting as a heatsink.  Also, it's internal so you're not
> typically handling the device during operation.
>
> Even as the user who modded his 950q pointed out, there was no visible
> difference in performance.  This is just a case of somebody sticking a
> heatsink on something just because they can.
>
> The devices in question draw less than 500ma @ 5V during operation,
> which is the limit set by the USB standard.  In fact, I've taken
> direct power measurements and compared them against the devices under
> Windows as well as other tuner products.
>
> Go to any modern LCD television and grab the F-connector that the coax
> cable is connected to (leave the coax disconnected for a few minutes
> though since it can act as a heatsink).  It will burn your fingers
> just as much.
>
> Devin
> (the guy who did the 950q and 801e Linux driver support)
>
> --
> Devin J. Heitmueller - Kernel Labs
> http://www.kernellabs.com


Thanks Devin.

Even 500ma at 5v (2.5w) is significant to me - I'm trying to build the
lowest power machine possible, and 7.5w for three tuners is almost as
much as the whole rest of the system...

Perhaps you would know - one of the pages I had read said that the
heat was related to the multi-purpose chipsets - chips that include
analog capture, and have hardware MPEG2 video encoding onboard.   I
believe both the 950q and 801e are in this category...

Have you tried any chipsets that are digital-only tuners, without any
of the circuitry for the analog side?

Thanks again
- rsh1k