Mode of operation? Filters IF or audio tone and notch in use?
My friend reported that the noise came through on my signal and wiped
it out.
Really? This is an interesting fault. I don't think that rig uses any
audio stages that are common to both transmit and receive, so an
oscillating audio stage would not do it. Maybe an oscillation in a power
supply regulator inside the radio. Three terminal regulator ICs often
need bypass capacitors on input an/or output to keep them from becomming
oscillators.
Oscillation in the IF system that has the filter that rejects the
opposite sideband? One of the only stages that is actually used in both
TX and RX.
Multiple tones coming out of a single BFO? If you try opposite sideband
or different mode that would change it or make it go away, if that were
the source.
What band? Any band you operate on or just one? What about into a 50 ohm
terminator instead of an antenna? Do you always operate on the same
frequency? Maybe it is an external source. Try changing frequency. Maybe
a spur from one of the oscillators in the rig (related to idea of
multiple tones from the BFO.)
DE N6KB
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