[Elecraft] Re-visiting The K2

[David Yarnes]

Hi All,

It has been a long time since I built my K2 (#72).  But it still is working 
like a champ!  I started pondering the idea of having a 2nd K2 to leave at 
our summer location so I wouldn't have to haul an extra radio back and 
forth.  Building another one could have been fun, but a friend of mine 
decided to part with his relatively new K2 in order to step up to a K3. 
Since he is an excellent builder, and the price was right, I took it off his 
hands.  This K2 is relatively spartan, but it did have the SSB module and 
the 160 meter option.  He had the ATU kit still in the package, so I bought 
that too.  Adding DSP was very tempting, but I'm so impressed with the 
Datong filters (actually an analog filter, but it works bettter than just 
about any DSP outboard unit I've ever tried) I decided to just use one that 
I have.

As I expected, the K2 works flawlessly, and probably better than my original 
unit, although I haven't put them side by side yet.  I plan to do that 
though.  That could be interesting, and also could determine which one stays 
home!

I had forgotten how involved building the ATU module was.  It's not that it 
is all that difficult, but there is a lot to the process.  It took me a lot 
longer than the bag of parts suggests!  But it all went together smoothly, 
and now it is installed and doing its job well.  Elecraft ATU's are really a 
good add.

I have a small complaint about the ATU installation.  It is necessary to 
remove the K2's back panel, which also partially covers the bottom.  This 
includes having to detach the power transistors, which is something of a 
problem.  Those transistors are installed with thermal pads attached, and 
several small pieces of hardware.  It's not a simple process detaching and 
re-attaching these transistors properly.  The only reason you have to go 
through all of this is to install a 2 pin male connector at P6 on the RF 
board.  I think that connector should be part of the K2's construction 
whether an ATU is definitely planned or not.  It certainly would simplify 
later installation of the ATU, and the cost of the 2 pin connector has to be 
only a nominal amount.  It just doesn't make much sense to me that you would 
not istall this part when you build the K2.

There was only one instance when I thought I had a construction problem. 
That came during the "Preliminary Tests" procedures on P. 13 of the 
instructions.  During the procedure where you check to make sure all the 
relays are functioning, I got a nice, clear clicking sound on everything but 
N1 and N2.  But when I exited the menu, and then cycled between antenna 1 
and antenna 2, the relays were clicking appropriately.  Now they all click 
when I cycle through using the ATU menu setting.  Not sure why this 
occurred, but both antenna positions are working fine now, and I don't see 
any problem around K17 and K18.  Hopefully I haven't overlooked anything.

So, now I will go do some A/B testing between the two K2's.  They sound very 
similar to my ear.  Interestingly, both seem to max out around 12 watts. 
They both are a bit anemic on audio output, but it is adequate.  QSK is 
superb, and I've gotten very nice audio reports.  The K2 was an excellent 
radio in 1999, and it still is today.  Heck, I'm ready for "SO2R" operation!

Dave W7AQK