Receiver active mixers (nothing else than low level amplitude modulators)
are generally designed to work with relatively high level signals to limit
their inherent distortion. The mixer distortion is well present, in spite of
opposite opinions, expecially when that device is biased to have more gain
along its linear curve.
This fact leads to design high level mixers (mostly passive) that finally
show a worse NF and a lower gain, if not a loss, than a dedicated amplifier
module could do. Ultra linear devices, with no other purpose than
amplifiying with low distortion meanwhile keeping a better noise figure, and
not one of the mixer's input, are infact more easily and succesfully placed
behind the antenna input of good receivers and spectrum analyzers.
73,
Mauri I4JMY
-----Messaggio Originale-----
Da: Lamb <k7fm@teleport.com>
A: measures <measures@vcnet.com>; AMPS <amps@contesting.com>
Data invio: sabato 1 gennaio 2000 6.23
Oggetto: Re: [AMPS] The 3/2 Power Law
Of course there are bad mixed designs which do cause
> distortion.
> 73, Colin K7FM
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