Many thanks to Henk, PA0C for helping me out with some troubleshooting ideas.
As it turns out, I seem to have exceeded the dielectric breakdown voltage of D5 on the KXVA3 board during my SO2R operations. This introduced static bursts on both the main antenna and the receive antenna. I ordered a new part from Mouser for less than $1, it is installed and the radio is back to performing as it should.
One non-related item that I did find, was during a thorough inspection of the RF board I found that one half of L37 had never been soldered to the circuit board. The K3 seems to have worked just fine for 10 years without the part being soldered to the board but I soldered it anyways.
Thank you for the troubleshooting ideas.
I have connected the IF output to a second receiver and the noise is still present.
I am currently looking into how to look at the synthesizer output with a SpecAn.
This could be anything, but sounds like an almost broken capacitor.
You need to find out where in the receiver the noise is generated.
A good place to start is the IF output connector.
Connect a second receiver to the IF port and see if the noise is still present when tuned to approx. 8.2 MHz
In case not, it is generated in the IF, DSP chain
If yes, most probably it is the front-end.
This will lead to the next, more detailed steps.
You should also check the syntheser output on a spectrum analyser to see if the oscillator is "clean" or listen to it on a second rx.
Best to see if you can use a TMP connector somewhere to tap into the signal.
-------- Oorspronkelijk bericht --------
Datum: 25-10-2020 01:45 (GMT+01:00)
Onderwerp: [Elecraft-K3] K3 Receiver Noise Troubleshooting
I have a K3 that has worked great for many years but now has a noise source somewhere in the receiver. The radio still hears stations but there is a new source of static bursts on all bands. It sounds like there is a thunderstorm in the local area with bursts on 160M peaking at S-9 +40 and on 10M they peak around S-6. When I disconnect the antenna, stations go away but the static noise remains. I have a video that I can send a video of what I am trying to describe.
I have taken the radio apart and reseated all of the connectors (some are gold and some are tin) and the problem persists.
I do not have a sub receiver installed.
I am looking for suggestions on what to try next.
Thanks and 73