Same effect can be seen in the output transformers since none of the K3's transformers are magnetically shielded.
I found 20 to 25 dB difference in induced hum by rotating the K3 in three dimensions. Whether the hum minimization orientation puts the K3 in a usable position is another question. Another alternative is to replace the transformers with shielded versions, assuming space on the PCB is available and a shielded transformer with the same electrical specifications and footprint is available. In my case, the hum field is only (so far) in the basement area of my workbench. Jack Gerard Jendraszkiewicz wrote: > Hello, > > I wonder if anyone else experienced this type of problem and has a > possible solution ? > > Independent of any connectiions I found out a 50Hz hum on my Line-In > audio. After a long investigation I figured out > it was a coupling with other transformers external to the K3. The > transformer of my ampliflier ( 10" away from my K3 ) couples an audible > 50hz hum into the Line-In input. It seems the small isolation > transformer in the Line-In line is prone to pickup of > 50Hz/60Hz magnetic field. Always I'm able to simulate it with other > transformers. > > Increasing the distance from the K3 to the amplifier is not an option as > my shack space is limited. Any sugestions to prevent it? > > 73 Harry DM5TI > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
