Sam - If you are running the K3 on battery power, then obviously power supply hum isn't the problem. Some possibilities:
Try changing the orientation of ANY AC operated device near the K3. If possible, remove the item temporarily as a test. If it is not possible to move the external device, then at least try rotating it 90 degrees in at least 2 planes (one at a time) and test again. I have experienced instances where a external magnetic field was "modulating" a VCO inside a radio, and causing the sort of problem you are experiencing. The problem may be coming from something other than a power supply. I had an instance where the magnetic field from a TV set's horizontal oscillator was affecting the VCO in a Kenwood 9800 VHF set, and causing it to transmit spurs up and down the band at 15.75 kHz intervals. That computer power supply could be a possible culprit. Try turning it off (remove the power cord to insure a complete shutdown) just to see for sure. If you have not already tried this, try running the K3 with no external connections at all - other than perhaps the battery source. That means no antenna, no microphone or key paddle, nothing at all. It goes without saying that any other connections should be removed for this test - no computer interface, no external speaker, no nothing except for the K3 by itself. I believe you should be able to key up the K3 from the front panel using either a "test" mode or manually operated transmit. Set the power to as low as it will go before making this test. 1 watt or less of RF will not damage the radio even if the antenna is completely disconnected. Listen on another receiver to see if you still hear the hum. If you do, and if you have eliminated any possibility of influence by an external AC field, then the problem is internal to the K3, and it needs repair. If not, then try attaching external connections one at a time until the hum comes back, and you have found the basic problem. It is possible that a "ground loop" from one or more external connections is causing the problem. Let us know what you find after making these tests. - Jim, KL7CC Sam Morgan wrote: > <snip> > > I just went to battery power and hear the same hum > > I have turned on a radio shack swl receiver sitting across the room > and am using 0.10w output > > <snip> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
