[Elecraft] [K2] External Fan Hum

[Fred Jensen]

I tried an AC muffin fan on my KPA100 ... while it worked wonders 
keeping the heat sink cool when I was using the K2 for RTTY, it induced 
hum.  I switched to a brushless DC fan from an old computer and it 
solved the problem.  I can't tell you if the K2VCOSHLDKIT would work or 
not since I opted for another solution.  The DC fan was inaudible 
acoustically.  I fastened it down with a little tab of velcro, blowing 
down onto the heat sink.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 11/7/2018 6:24 AM, erusst at att.net wrote:
>    On Wed, Nov 7, 2018 at 7:51 AM, Steve Kavanagh via Elecraft<elecraft at mailman.qth.net> wrote:   I was experimenting with an external 120V AC fan to improve the cooling of the KPA100 during CW Sweepstakes this past weekend.  The cooling worked fine but the fan caused some hum on received signals (and presumably my transmitted signal as well).  Placing the fan towards the right and back (away from the speaker) reduced the hum to a pretty-much unnoticeable level for CW, though through careful checking on a very strong signal I could still detect it by ear.  I haven't tried it yet but I suspect it isn't good enough for FT8.
>
> I assume the K2VCOSHLDKIT would fix this.  But I also noticed, going through the archives that Eric had suggested a DC fan in the same location.  Does anyone know if I might expect less hum from a 12V DC fan?
>
> 73,
> Steve VE3SMA
>