K2 #4150 lives!

[DaveL G3TJP]

After building my K2 #5551, a very busy friend allowed me to build his, #4150.

This had started life as a much earlier K2 for which he'd obtained upgrades, a new serial number and a set of pre-wound toroids to bring it up to the latest specification but unfortunately, due to time constraints, he'd had little opportunity to organise and get down to its construction.

Problems encountered were:
1. No BFO signal at TP2 caused by fitting a  2N7000 instead of a J310 at Q24. (Doh!)
2.  The BFO range didn't go down low enough to achieve the recommended CAL FIL settings.  Gary advised fitting a 1 to 4pF capacitor between ground (X3/X4 grounding points and junction of X3/X4 and L33.  With the K2 upside down, front panel towards you, it's the lead at the right hand side of L33).  A 1.8pF capacitor reduced the BFO's lowest frequency while not affecting its upper frequency.
3. The frequency counter probe came apart and when it was repaired the series 10pF capacitor was forgotten, leading to some crazy, unstable readings (thanks for the reminder, Gary).
4. Excess current (<3A) being drawn on 40m tuneup.  L1 adjustment having little effect.  All other bands tuned up just fine.  This was traced to L25/L26 having been supplied with 16 turns each, rather than the specified 14 and 12, respectively.  Everything tuned perfectly after correcting the number of turns.  Moral - double-check others' work as well as your own!

All in all, another super little rig, the building of which has given me enormous pleasure.  Thanks Elecraft for a truly superb kit (that even an eejit like me can get right - twice!), thanks to my friend for trusting me to build it for him and a very special thanks to Gary AB7MY for super support.

Now, how to get another K2 to build?  Unfortunately, it's impossible to put one over on the "domestic supervisor" HI!

DaveL  (G3TJP)
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[PE1E]

Great fun to work at this moment US on 14 MHz with only 10 W bare K2 SSB
from PA-country ( Netherlands ) with only a 7 mtr vertical wire without
radials ( KAT2 obviously tunes great ).
I wonder how my bare K2 could be heard in US between all those big EU >1KW
S9+20/40 canons but it does work for me !
My K2 Rx performs great in this contest mess..just miss the IF shift...and
tweaking the K2 filters against bfo to mimic IF shift is kinda tedious.

Peter, PE1E


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