40m birdie only on ham sub band 6500 2.12

Charlie N5WE · March 15

Today I first noticed a birdie appear in the 40 m band. It appears to only be present slightly out of the ham portion of the band, but only when the radio has switched into the band pass filters for the 40 m ham band. As soon as you slide the pan adapter away from the ham sub band and you hear the relays click, the birdie will go away. As soon as you slide the ham portion of the band back into view and hear the relay, it will reappear first as a swipe, and then slow down to a steady warbly birdie. It appears to only be present when the ham sub band is in the display.

It’s present, whether the antenna is hooked up or not, and I’ve gone through the usual, turning off everything in the shack as well as using a different computer with smart SDR. I’ve disabled the router, the switch, and every other electronic device in the shack. Attached is a video of it. Is this hardware? Normal?

https://imgur.com/a/RcnRvk9

John KB4DU · March 15

That seems really strange. Only one more test I can think of to isolate it. Can the rig operate on a backup power source if the main house breaker is turned off?

Charlie N5WE · March 16

Thanks John, I can certainly try it. It is on a switching power supply, and I did swap it to a different switching power supply (disabling the first). Just don't understand how its not there when the "WIDE" (note in the top right corner) bandpass filters are engaged, and returns when the ham bandpass filters are engaged. I just happened to be tuning above the 40m band and noticed it. Then I realized there was no antenna plugged into the radio, not even a jumper. Also noted is that it starts as a sweep and slows to a steady signal, but it is reset each time you switch the bandpass filters in and back out.

It really isn't a big deal, because it appears to be present only in that one small span, which is out of the 40m ham band.

40m birdie only on ham sub band 6500 2.12

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