Noise Spikes on 40 meters

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  • Updated 2 weeks ago
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I am having a noise spike issue only on 40 meters with my new 6400M. When I first tune it on from a cold start, the receiver is good, no noise spikes. I can be in listen mode for several hours and the noise spikes do not appear. However as soon as I transmit, the noise spikes appear and do not go away. A reboot does not eliminate the noise spikes, Only when the 6400M is power off for several hours and then powered on are the noise spikes gone. Then when I transmit they immediately reappear. I tried different power supplies, (Astron 35 amp and MJF25 amp) and even a deep cycle 12V 100 amp battery. Same issue. Also when I disconnect my antenna from the 6400M , the noise spikes disappear, then reappear when the antenna is reconnected. It appears the noise is coming into the receiver via the antenna. It seams like there is some front end oscillation occurring right after transmitting. I opened support ticket number 22739.
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Thomas NE7X

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Posted 3 weeks ago

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Photo of Gerald - K5SDR

Gerald - K5SDR, Official Rep

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Official Response
Thomas,

If the noise spikes are not present on a dummy load but are present on an antenna, you can be certain that they are generated outside the radio.  Depending on the time of day and which neighbors are home, I see almost those same signatures from time to time.  It may be in your hours or a neighbor's house.  I can almost assure you it is not the radio itself.

Gerald