[Elecraft] Mic Gain, K2/100

[Geoffrey Mackenzie-Kennedy]

Ron AC7AC wrote:


There were some mods that changed the gain distribution within the K2 RF and
audio paths that some suggested could increase the IMD. I suspect that's
where the comments about not doing them on a KPA100 came from, although it's
hard to see how an S-9 signal running 5 watts is any less sensitive to IMD
issues than an S-9 signal running 100 watts <G>.

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Perhaps the comments about not doing them when a KPA100 is used were based 
on the fact that the level of IMD products at the output from the cascade of 
a K2 and KPA100 could increase quite 'rapidly' as the level of IMD products 
from the K2 increased. Two reasons being that the KPA100 exhibits gain and 
is itself not perfectly linear. So the level of the IMD products around a 
S-9 signal from the K2/100 could be greater than those around the S-9 signal 
from the K2.

A similar situation occurs in a receiver where a 'weak' IF or IF branch 
amplifier can ruin the performance of the overall receiver even if it has a 
'strong' front end.

73,

Geoff
GM4ESD