[Amps] TX IMD

Jim Thomson jim.thom at telus.net
Wed Nov 18 12:01:56 EST 2015


The ARRL  uses  db below pep instead of db below one tone  ( of a 2 tone signal) .
Thats fine  with me.   S meters  are  PEAK reading devices.  So if ur IMD is say  30 db below pep,
that’s like  30db below the fellows S meter reading.   IE:  say station A is  30 db over S9. 
His splatter  will then be  S9.   That’s nothing to write home about.  If he is 40 db over S9,
then his splatter will be  10 db over S9.   Are you folks starting to get the point ? 
Lousy IMD is  semi ok on bands with lots of noise, but when noise is low... IMD rears its ugly
head. 

Most S meters  are NOT  6 db per s unit.... below  S9.   Even with an S9 signal.... u will easily hear
splatter 30 db below that..or typ S1- S2.  ( in the case of lousy TX IMD, like  -30db pep. ).

It’s the higher order IMD  u gotta worry about....like the IMD 7-13 products. 

Jim  VE7RF



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