On 1/13/2012 10:30 AM, Phil Hystad wrote: > I disconnected EVERYTHING. Nothing on the back panel of the K3 at all except > for a Li-nano-phosphate battery as my power source.
Was your antenna connected? If so, where is the coax shield connected to ANYTHING -- the earth, other gear, at a tower, etc.? These are all paths for AC leakage current, and your K3 can be in that path. > All AC off at the breaker panel for this room. The only electrical > equipment on was my K3 via the battery and my Macbook Pro laptop via its > battery. > > Given those conditions, the hum was still there. > > Jim Brown suggested that I consider TXEQ to cut off the low frequencies, I > did max cut for all frequencies up to 400 Hz. The hum did not start being > attenuated until 400 Hz cut. But, max cut on 400 Hz did not attenuate it > completely. I did not do higher frequencies. Then what you have is BUZZ, NOT HUM. HUM would be affected ONLY by the 60 Hz frequency band. The coupling mechanisms are entirely different. That's why it was my first question! BUZZ is leakage current from the AC mains power, OR, as Ron suggested, a flaky shield connection of the mic. BUZZ is almost never due to magnetic coupling, so magnetic shielding doesn't matter. What DOES matter is ELECTRIC shielding, which is what the cable shield provides. And MAIN thing that matters is BONDING -- CHASSIS TO CHASSIS, and from the combination of those chassis to the station ground, AND to the power system ground. Study http://audiosystemsgroup.com/HamInterfacing.pdf 73, Jim Brown K9YC ______________________________________________________________ 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
