Re: QMX (80-20m) Rev 2 Harmonics
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Hi Bryan
You didn't say how you connected the TinySA to the QMX. QMX would need a 50-ohm dummy load and proper attenuators. Just putting the TinySA nearby doesn't provide good enough measurements. So please check that as you need to find out if this is the problem or if there is an actual problem with your QMX.
73 Hans G0UPL
On Sat, Jan 13, 2024, 8:05?AM ReefKeeper2K23 < bgraf2311@...> wrote: Good evening,
I just finished assembling my QMX (80m-2m) rev 2 kit a couple of days ago and I'm in the process of testing it out. This is my first HF transciever as well as my first kit build so please bear with me. I hooked it up to a dummy load and then to my Tiny SA Ultra spectrum analyzer to see how clean the signal was on the various bands after calibrating the analyzer. I am seeing elevated harmonics on all bands that are suppressed to some extent but if I understand correctly not enough to be in compliance here in the US with FCC rules. Off the top of my head the level of the nearest harmonic was on average 27-32db below the fundamental frequency. Runing the latest firmware (1.00.014) and I've performed the suggested diode modification already.
Here's a screenshot off of the Tiny SA Ultra doing a harmonics test at 14.074Mhz. If I'm reading this correctly the 2nd harmonic is 28.6db below the fundamental frequency. Please correct me if I'm wrong.
Has anyone else tested their QMX and seen simillar results with regards to harmonics? If so how did you address it? I'm wondering if it's something I perhaps did wrong in assembly, configuration or if it's common to this particular kit.?
Suggestions?
Thanks,
-Bryan
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