New K2 builders (ONLY SN 00101 - 00260):
We recommend that capacitor C182 on the RF board be changed to 180 pF. (270 pF was supplied with your kit, and will work, but is not the optimal value.) This component change improves the receiver signal-to-noise ratio by a noticeable amount, particularly for medium to narrow bandwidth settings of the CW filter. Our apologies for this late change.
(NOTE: THIS ONLY APPLIES TO NEW K2 BUILDERS. FIELD-TEST K2'S ALREADY HAVE 180 PF AT C182.)
We will begin supplying a 180 pF cap with the kit starting next week. If you have already received your K2, you can use any type of 180 pF capacitor that you may have on hand, or we can send you one. The value is not critical; a 10% tolerance cap can be used.
Once you change C182 to 180 pF, you'll need to re-align L34, the I.F. amp's peaking control. Please do this as follows:
1. Disconnect the antenna.
2. Switch to 40 m, CW mode.
3. Select a moderate filter bandwidth (0.60-0.80) using XFIL.
4. Turn the RF GAIN control all the way up (clockwise).
5. Plug in a pair of headphones and adjust the AF GAIN control until you can hear some background audio noise or "hiss."
6. Using the VFO, find the very weak internally-generated "birdie" at 7000 kHz. (This signal normally can't be heard when an antenna is connected.) If you can't hear this signal, try switching to 80 m and looking for another weak birdie at 3589 kHz.
7. Using the wide end of the plastic tuning tool, adjust L34 for the strongest signal and minimum noise. This is best done by ear. Typically, the slug will end up about 1.5 to 2 turns below the top of the can.