Tune Output Comparison 6600 and K3s

kenb

I had a complaint today regarding my FT8 signal while using a KPA500 amp. This is a very unscientific look—I used an SDR with a short wire antenna to look at the output of the 6600 when transmitting FT8 and it looked a bit rough to me. I looked again with just the Tune control on SmartSDR and saw that the signal was a bit asymmetrical. So what does my K3s look like?

Actually, different. I've attached the screen shots. Both were running into a dummy load with both rigs set to transmit a 100 watt tune signal.

Is this meaningful? The spurs are down 30db on the Flex, but look rougher. The spurs on the K3s are not quite 30db down, but look cleaner to me.

I sometimes use my KPA500 amp at ~200W output with the Flex on FT8.

Is this something I need to go deeper into? I use the Mac version of SmartSDR and the latest firmware for the 6600.

Thanks!

6600 above.

K3.

Ken Wells

What is the LEVEL meter PEAK indicator showing when you transmit FT8 from the FlexRadio?

It should be about 2 dB below the 0 (red) indicator for FT8.

kenb

Thanks, Ken…

The gain is set to ~2 db below the red. Doing more digging this weekend, it appears that the 6600 is transmitting some hum when transmitting just a tune signal. Doing the same with the K3 fed with the same power supply, there is no hum. So, I need to narrow this down some more.

73…