LA3ZA Unofficial Guide to Elecraft K2 Modifications

Modifications to the Elecraft K2 that took place for various serial numbers prior to 3000.

Reference

Description

Comment

Complexity

K2 Status

Source

Basic K2 Improved Performance

Changed turns ratio on T7 on RF board Changed from 11:3 to 20:5 from rev B to rev C manual. Changes termination of X-tal filter for more gain esp. at low bandwidths In Rev C manual (19 April 2000). Elecraft
Reduced no of turns on T3 (RF board) Changed from 10 turns bifilar to 5 Better efficiency of PA In Rev C manual W6EMD
R18/19 in audio mute circuit (ctrl board) replaced by jumpers Short out two resistors

More audio gain

All K2s after May 1999

Elecraft

¤Frequency shift on transmit due to walking VFO

Caused by cycling of power for optical encoder combined with a position close to the border between counts.

Important, but only required for firmware prior to 2.02E.

Simple, just an installation of a strap.

Recommended for firmware prior to 2.02E. Fixed in all K2s with serial numbers 2696 and above.

Elecraft

×More accurate current metering

Some RF gets into current sense circuit on 160/80 m

Simple to do (control board)

Make C42 0.1 µF (100 nF)

Included with K2s with S/N 2856 and higher  

Elecraft

RF Detector Improvement

More accurate indication of RF output at higher frequencies

Replace a diode and a resistor

In all K2s some time before Aug. 2001

Elecraft

Improved current measurement accuracy

Change control board R7 from 1.96k to 1.78k

 

 

In all K2s some time before Aug. 2001

Elecraft

SSB Option KSB2

Increased ALC delay time

Improve intermodulation distortion in PSK31 transmission

Important improvement of PSK31 performance with no side effect on SSB performance

Change 3 resistors and a capacitor

Changed in all KSB2 kits shipped after Sept 5, 2001

KI6WX


Items marked with × are implemented in my K2, while ¤ denotes modifications that I have tried, and then removed.


First version 8 Nov 2001, last update 16 May 2005.


73, Sverre Holm, LA3ZA