"Cecil Moore" wrote ... > Richard Crowley wrote: >> So is there anything at 9 KHz that could be an intermittent >> source of CW? > > 9 KHz is in the audio spectrum so it is probably > the product of mixing. What frequency is the > receiver tuned to? What are the IF frequencies? > What are the intermod possibilities? It is being picked up directly by two Royer ribbon microphones which contain an active impedance- matching circuit implemented with a tube ("valve"). No IF involved there. On his AM BCB receiver, he was complaining about 790KHz. We likely have no way of discovering his IF frequency.