Transmitted CW bandwidth comparison between Flex 6700 and Elecraft K3 transceivers using latest versions of software/firmware in both transceivers.
Agilent N1996A Spectrum Analyzer; 10 Hz RBW
40m, CW mode, swept from 7040 kHz to 7060 kHz, 2 kHz per horizontal division
External CW keyer used and set to 60 wpm for all measurements
Internal oscillators used for both TRX (not external Ref. input)
RF sampled from Bird variable RF coupler
Output power: 50W into Bird TermaLine load
Flex 6700 60 wpm slider setting (YELLOW TRACE)
Flex 6700 10 wpm slider setting (LAVENDER TRACE)
Elecraft K3 QRQ Mode (BLUE TRACE)
At +/- 1 kHz spacing from Fc, occupied bandwidth is very similar at approximately -70 dBc.
At the moment, I have nothing from JA in the shack. However, I just measured the Expert Electronics SunSDR2 using the same test conditions but with two different CW rise/fall settings.
The GREEN trace is with the CW waveform rise/fall set to 5 ms in software. The YELLOW trace is with rise/fall set to 2 ms. With the faster ramp time, there's more than a 20 dB difference at +/- 1 kHz from Fc.
A true apples-to-apples comparison requires knowing the ARRL's analyzer test parameters, including preamp, RBW and VBW settings. Optimizing would probably drop the noise floor by 10 dB although the occupied CW bandwidth at 1 kHz would be unaffected and that's what I was most interested in.
use your settings. My spectrum analyzer can easily handle that. Only glitch could
be that I have no Bird equipment, I'll use the RF coupler I built last year. Will write about the results here. 73, Alex DH2ID
It would really help if you could overlap the plot images, or else plot their dB difference vs frequency. Offhand, these look so similar to each other that it is difficult to see any conclusion between the FRS 6K and the K3. I'm very interested in these results.
Also, what exactly do you mean by K3 QRQ mode? What keying speed? It would be interesting to compare real-world speeds from 20 to 30 wpm. This has mostly to do with keying envelope shaping and rise / fall times. It would be nice to compare apples to apples here.
Assuming both rigs use reasonable rise / fall times, around 6-8 ms, and both use raised-cosine shaping, then the only difference should be in the phase noise of their LO's, eh?
73 de Dave, N7AIG
Also when we did our testing, I found that there is no free lunch. When you go from nothing to full power in 5ms, you get a "fixed amount of noise" generated. You can place all of this right next to the carrier or you can spray it all around the band. I could (if I wanted) design a ramp that will do the latter and will make the ARRL plot look better than any others. The result will be that low-level noise is sprayed all over the band. So be careful what you measure ...