I didn't check your math, Jim, but that all looks about right to me. I know
that Ulrich Rohde has been recommending using such high-level tones for IP3
testing. This may be quite appropriate to test the *ultimate* IP3 of receivers
with AGC-controlled attenuators. Although I am certain ARRL will use the
standard level test tones, we may also do the tests at their specified levels,
especially if there is a sound technical reason offered for doing so.
Depending on the architecture of the receiver, the IP3 could come out right on
the money, or somewhat different, at the ARRL test levels.
The specified IP3 is overall quite impressive. While some radios have
approached +25 dBm at >20 kHz spacing, seeing that hold to +24 dBm at 5 kHz
spacing will be quite a coup for Ten Tec! I can't wait to get one for testing!
Do keep in mind that as we get into true software-defined radio through DSP,
there are apt to be a number of things that need to be tested additionally or
differently. I will do what we have always done and solicit advice from our
advisors and the manufacturers, of course.
73,
Ed Hare, W1RFI
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