uBITX v5 TX IMD measurements #ubitx #two-tone #v5

Doug Hall


I just finished measuring the two-tone TX IMD on my v5 uBITX. These are 3rd order products, and I measured relative to either tone. Since the ARRL states their measurements relative to PEP I have included that as well, for those who sleep better at night secure in the belief that their radio is clean :-)

This is at 10W PEP using 700 and 1900 Hz tones. My radio puts out 10W from 80 through 20 meters, and falls off to 5W on 10M:

80m -25.5 dBc (-31.5 dB PEP)
60m -22.5 dBc (-28.5 dB PEP)
40m -22.0 dBc (-28.0 dB PEP)
20m -24.5 dBc (-30.5 dB PEP)
17m -21.0 dBc (-27.0 dB PEP)
12m -25.5 dBc (-31.5 dB PEP)
10m -22.0 dBc (-28.0 dB PEP)

As my flight instructor used to say after one of my landings, "I've seen worse, but I've seen a lot better." This is probably not atypical of IRF510s.

Now I'm going to hook up the 'scope and look at the CW waveform.

Doug K4DSP

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