Re: Intermodulation Performance

ajparent1/kb1gmx
 

Warren,

The -30dbc for IMD of third order is good.  Whats no so good is only 2W.

It was actually hard to find that data for a lot of the QRP/low power radios.
For many it doesn't exist.  

I never got as far as to measure that for uBitx.  I did it for the old bitx20
(2006 version) and it was not at all good at 4W and -20dbc.  Reworking
the amp  for better stability as that design oscillated when bias hit 60ma
improved matters to -25dbc at 5W. 

A lot of the newer 100W radios out there are barely -26dbc.
Nominally its measured at max stated output power or 10W for ubitx,
and anything better than -26dbc is as good as a lot of radios.

I suspect on 20M and up that will be limited by available power without
hitting 1DB compression point.  Once you hit compression all bets are off.

Allison

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