>
> Apparently there is a rule of thumb that says the third order
> intercept is 10 to 12 dB above the 1dB compression point:
>
> http://www.rfcafe.com/references/electrical/p1db.htm
> http://www.arrl.org/qex/2006/09/qx9letters.pdf
>
>
> Mike
> KL7R
>
This makes nonsense of the claim of 54dBm for 'our' mixer since 42dBm
is 15.8W, or 40v pk into 50 ohms.

This mixer cannot possibly be linear beyond an input voltage of 2.5v
pk, or 62.5mW or 18dBm. Add 12 to this and you get 30dBm as an
absolute maximum for estimated IP3.


The figures for a mixer with 3.5v bias are 1.5dB higher.


It is beginning to look as though an IP3 of 20dBm might be something
to hope for.

Andy G4OEP