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I have K3/100 with KAT3, KRX3, KXV3A, KBPF3. Added KDVR3 this weekend along with 1.8 and 6Khz filter to the main receiver.
Was talking with another friend after upgrades installed without issue. He too is a K3 owner. He noticed a faint audible tone on my SSB signal with key down only, i.e. when I stopped talking. Both of us have an SDR-IQ hooked to the IF out and we were both able to confirm the spurious emission. (I disconnected the SDR-IQ from the K3 and used it as a spectrum analyzer).
The spur(s) are present on USB/LSB, all bands. AM and CW transmit spectrum look good. Best as I can figure AFSK RTTY transmitted signal without spurs. Spur IS present on E-SSB which I also checked out (so that is through the 6Khz filter).
The amplitude of the spur is not effected by MIC GAIN, COMPRESSION, or POWER. As soon as K3 goes in to transmit with no audio, the spur(s) show on in the spectrum--even at 0.1W output. I do not need to have a microphone connected to the K3 either. Spur can be seen/h with all other equipment in shack off, i.e. amplifier, computer. Present when computer LINE IN/OUT disconnected.
With the new DVR installed, I believe I can hear the tone being recorded, again with the DVR placed into record and me not talking, when I play back the recorded message, I can hear a faint high pitch tone---mind you it is very subtle but clearly there.
Spur also present when K3 running on battery power. Spur also confirmed with an Icom transceiver in the shack as well.
I posted SpectraVue images to the web at wh7w.blogspot.com
Thanks for having a look.
73 and Aloha to all
Mark WH7W
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