Igor says:
>Its 3rd order intercept point is +30dbm,
>for a $1500 dollar receiver is very good.
A 10 dB noise figure on SSB with a +30dBm 3rd order intercept point is
really good - except that you need -164dBc/Hz of phase noise averaged across
the SSB bandwidth to make any use of it. Generally speaking, observation
suggests that a +20dBm intercept point is good enough, if used with
attenuation to move the dynamic range starting point. Anything less than a
+20dBm intercept point with 10dB noise figure puts it in the second class:
but a 15dB noise figure and 25dBm TOIP with the RF amp off and 20dB NF with
30dB TOIP with attenuation is OK. This is because it's very rare to be
really digging for sensitivity with -20dBm signals on the same band. Even
then, there is their phase noise to consider.
See my paper at RF Expo, Anaheim, 1986.
73
Peter G3RZP
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