[Elecraft] K2/100 Amp problems

Carter W. Craigie [email protected]
Mon May 12 19:11:00 2003


Hi Elecrafters!

After about two months of perfect operation, my K2/100 100-watt option
is acting strangely.  Here's what happens.

In the morning, for instance, I turn on the K2. AT TURN-ON, the fan
IMMEDIATELY comes on (on HIGH!). If I tap the paddles I see a PA HOT
message on the display screen. If I do nothing, it might just stay
there, but more often than not, after about 10-15 minutes, the fan
stops, and all is well.

At other times, if I tap the paddles a SECOND time, I see a HI REFL PWR
message on the display screen; the CW tone is VERY distorted, and I
decide not to touch the paddles again.  At this point I have turned off
the rig, waited a minute or two, and then re-started the rig.  Sometimes
the fan still comes on running at the high speed.

Something else happens too!  My receive audio seems to fade away!  And
it will come back (and I am thankful!) but then it fades out again.  And
if I am SENDING CW, my side tone sometimes goes so far down I can barely
hear it at all! I wonder if I'm putting out ANYTHING AT ALL!

Something else: if I try to tune the K2 in the first few minutes after
start-up, and my power level is set at 50-90 watts, the tuner will give
me a reading up in the 1.7 to 2.0 level!!! But if I reduce my power
setting to under 9 watts, the SWR drops IMMEDIATELY to 1.0 or 1.2.
Hmmm...

What have I done so far to correct this situation?

1. I switched rig top lids, going back to my original K2 lid which holds
the battery and automatic antenna tuner for LOW power (Up to 10 watts).
Everything worked perfectly!  So I believe the basic rig is working just
fine; it must be a problem in the 100-watt option.

2. I examined the amp and discovered that the lead of that big black
capacitor in the back right corner had come separated from the center
pin of the SO-239 50-Ohm antenna connector. Very carefully, I reheated
the connection and am now sure I do not have a cold solder joint there.

3. I remembered that during my original assembling I had nearly stripped
the delicate screw threads of one side of Q1, one of those big flat
transistors; well, sure enough, that screw WAS loose!  I removed it,
took off its lock washer, and replaced it. THIS time the screw found a
tightness, and I quickly let good enough be good enough!

4. I re-assembled the metal plate, and switched in the K2/100 cover. And
the rig WORKED!  I thought I had fixed my problem.

But the next morning I turned on the rig to find the exact same
conditions I had before my "repair!" RATZ!!

I wonder what I should do now...  I am off to Dayton on Thursday, so
don't know if I can do much of anything between now and then, but I sure
want my good operating rig to work again--as it had for a month or two
after completing the option!

73,
Carter Craigie N3AO
K2/100 S/N 678
K1 S/N 159

Carter W. Craigie
5 Faggs Manor Lane
Paoli, PA 19301-1905
(610)993-9623
[email protected]
or
[email protected]