[Skimmertalk] QS1R (Rev C) over heating?

[Dave]

Thanks for the feedback Alex

I’m glad it’s not just mine! My second option is either a switching
regulator based on an LM2596,  or a big heatsink on the LM317, with a large
hole in the case and a cooling fan. I prefer the switching regulator
option, subject to it not generating QRM.

73 Dave, G4AON

On Fri, 17 Jul 2020 at 13:22, Alexander Ranaldi <alexranaldi at gmail.com>
wrote:

> I placed some enormous copper heatsinks on my regulators and put the QS1R
> board itself in a new enclosure with a built-in linear power supply and two
> 80mm fans running at ~2k RPM.  Seems pretty stable in that configuration. I
> haven't checked the heatsink temperatures though.
> Alex w2axr
>
> On Fri, Jul 17, 2020 at 7:49 AM Dave <dave.g4aon at gmail.com> wrote:
>
>> My QS1R failed recently. The fault was the 1.2V supply, which is fed from
>> an L1117 1.2 regulator.
>>
>> Running the 1.2V rail from an external supply showed a current draw
>> around 300mA when listening to a broadcast station with SDRMAX V software,
>> but around double that current when running 7 slices with CW Skimmer.
>>
>> The original regulator, which uses the PCB as a heatsink, seems
>> inadequate for the current needed by the Cyclone III FPGA. I tried an LM317
>> (TO220) regulator with a small heatsink, however the heatsink reaches over
>> 90C running 7 x slices with Skimmer.
>>
>> Before I bolt the regulator to the case, has anyone  checked their QS1R
>> for boiling hot regulators, modified theirs, or has mine an overheating
>> fault? By the way, Skimmer works with multiple slices, as does the QS1R
>> when used to listen “single channel” as in broadcast station listening.
>>
>> Thanks
>> Dave G4AON
>>
> --
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