[Elecraft] Hum coupling?

[Tom Hammond]

Hi Tom:

At 04:13 PM 10/28/04, Tom Althoff wrote:
>Ten-Tec recommended putting the matching speaker/power supply of my old 
>Omni-V on the RIGHT hand side of the radio.  The audio lines ran on the 
>left side and the transformer in the supply caused hum on receive.
>
>I'm experiencing similar AC hum on the K2 audio.   The K2 sits on top of 
>my Titan II and when the HV is set to operate (kicking in the big HV xfmr 
>directly under the K2) I get the hum.  If I pick the K2 up and move it 
>about 3" away from the Titan then all is well.
>
>Has anyone else experienced hum from nearby power transformers?   I plan 
>on using a 10Amp analog supply (not here yet) and anticipate I might have 
>to keep it away from the K2.   I suspect switching supplies do not cause 
>the same effect.

Yup... same scenario!

Supplies with big trnasformers, or even small ones carrying high current, 
can/will often cause hum on the K2.  Best to space them a distance away.

Switchers probably won't induce hum, but might cause in-band birdies by 
virtue of their switching frequency and (for some) lack of adequate filtering.

73,

Tom Hammond    N0SS