[Elecraft] [K3]PSK31 & DM780

[Ron D'Eau Claire]

Jim K9YC, wrote:

Older versions of the K3 produce 
a LOT of audio distortion at the Line Out for settings of Line Out 
gain greater than about 10. Distortion starts showing up weakly 
with a setting around 5, and is bonkers up around 50. I've heard 
that's been fixed in recent production, but don't know what serial 
number. I think it's also fixed with the audio mod that you can 
buy.

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Wayne's comments:

While the K3's speaker and line outputs meet the original K3 distortion
specifications at their intended levels of operation, we've found that
further improvement is possible, especially at higher volume levels, with
minor component changes. Low level distortion products can be further
reduced at both outputs. These changes are being incorporated into new K3s.

The K3AFMDKT modification kit contains the parts to make both speaker
amplifier and line-out audio output modifications, but you can choose to do
either or both, as they are independent.

Note: The headphone output of the K3, which uses a separate amplifier,
already has a very low distortion output and is not impacted by these
changes.

For details on making the modification, see:

http://www.elecraft.com/K3/mods/K3_AF_Stage_Upgrade_Instructions_Rev_B.pdf

These changes were incorporated in K3s starting at about S/N 1830 for the
speaker amp and at about S/N 1900 for the Line Out. 

Ron AC7AC