A previous discussion was about the Xiegu X6100’s spurious emissions. At that time I offered to examine the device if someone made an X6100 available to me.
Ben, GW4BML gave me his Xiego on his last visit.
Today I want to keep my promise, although I’m not an expert in it.
My setup was simple. A power attenuator with a total of - 40db and a spectrum analyzer.
The display of 0db means 10W out each.
I measured at 3.5MHz, 28MHz and 51Mhz with 5W and 10W CW respectively and 12.8V supply.
From my point of view, the -50db required in Germany at 3.5-28MHz and -60db at 51Mhz are met. With one slight exception of 2db. Maybe experts can help more.
Tomorrow I will measure the Two-Tone Intermodulation Distortion.
Today I measured the intermodulation in LSB at the frequency 7,100Mhz. The NF signal consists of two tones at 800Hz and 1250Hz.
Theoretically, there should only be two RF signals in the lower sideband.
A signal at 7.100MHz - 800Hz = 7.100MHz - 0.0008MHz = 7.0992MHz
And 7.100MHz - 1250Hz = 7.100MHz - 0.00125MHz = 7.09875MHz
In fact, common TRX produce more mixed products. First, two directly above and below the two signals. And more also away from the sideband. The infamous splatters. The higher the audio level, the more significant this unwanted effect becomes.
This is fine as long as the adjacent secondary emissions are -30db and the others are significantly lower. If the audio level is excessive, the value can increase to -20db. However, this usually does not lead to greater comprehensibility. You can clearly see in the spectrum that the desired two signals do not increase significantly, but the intermodulation clearly.
Here are the spectra at 5W, 10W and 10W with (too) high audio levels. It’s all ok!
