u-Tune equivalent for the K3?

[Bill W4ZV]

         For the record, I made a mistake in calculating
IMDDR3 for u-Tune.  It's actually identical with/without
u-Tune at 69 dB.  The +11 dB improvement in IP3
could just as easily have been achieved by adding
11 dB of attenuation.  Which is why IP3 can be very
misleading.  The base data set is below for those
interested.

                         73,  Bill  W4ZV

Two-Tone IMD Testing** Measured Calculated
Band/Preamp Spacing Input level IMD level IP3

14 MHz/Off 2 kHz –53 dBm –122 dBm –19 dBm
–43 dBm –97 dBm –16 dBm
0 dBm –29 dBm +15 dBm

So, IMDDR3 = -53 dBm - (-122 dBm) = 69 dB
(as shown in graphic on front page)


With u-Tune (preamp off): Measured Calculated
Band Spacing Input level IMD level IP3

14 MHz 2 kHz –43 dBm –112 dBm –8 dBm
–33 dBm –97 dBm –1 dBm
0 dBm –44 dBm +22 dBm

So, IMDDR3 = -43 dBm - (-112 dBm) = 69 dB


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