You're a genius.  I replaced the diodes and the K2 is now working correctly.  I 
had to use a NTE part that was compatible.  I used the NTE583, but I think I'll 
need to recalibrate, because when I set it to 5 watts and turn it to tune mode 
the manual tuner says its 10W, and when I set the power to 20 watts, the manual 
tuner say its 45 watts.
 
I hooked it up to my KAT100 Autotuner, and it doesn't seem to be working 
correctly.  When I put it in tune mode, I can hear all the relays popping, and 
when it stops, it always says its 1:1.  I also do not see all the leds light up 
showing the SWR like it use to.  The only leds that light up are the Antenna, 
and Power Range lights.  I set it to daylight, and dark modes and the lights 
for Antenna and Power Range brighten and dim like they should.  They also seem 
to function correctly, when I change antenna, the light follows the setting.  
The Power Range also seems to function correctly, as when the power is set 
below 10 W the low one is on, and above 10W the high one comes on.  I'm not 
sure if the K2 is not measuring the SWR correctly or if the ATU is not 
communicating it correctly back to the K2.  What are your thoughts?

--- On Fri, 7/2/10, Don Wilhelm <w3...@embarqmail.com> wrote:


From: Don Wilhelm <w3...@embarqmail.com>
Subject: Re: [Elecraft] Fw: k2
To: "Scott McBain" <ke5...@yahoo.com>
Cc: elecraft@mailman.qth.net
Date: Friday, July 2, 2010, 7:29 AM


Scott,

The KPA100 wattmeter is not communicating the power level back to the K2 
microprocessor and that means the drive is increased to maximum - yes, that 
will create splatter on SSB.

The most likely problem is that diodes D16 and D17 in the KPA100 wattmeter have 
been damaged.
Get yourself 2 new 1N5711 diodes and replace those diodes and it is likely that 
you will be back in business.  You can use 1N4148 (or 1N914) diodes if you do 
not care so much about the accuracy at low power levels.

As a preventive measure, remove the antenna from the K2 when not in use.  An 
antenna switch makes that an easy task.  Those diodes are easily damaged by 
static discharges caused by wind, rain, snow or lightning on your antenna.  You 
might want to consider creating a DC discharge path from the antenna as well - 
a 100 uHy choke across the feedline will create that DC path and not interfere 
with RF, even at 160 meters.


Scott McBain wrote:
> 
> 
> 
> I have a K2 with SSB, 100W PA deck, and 100W antenna tuner.  I sent this in a 
> while ago, and ya'll got it working great.   During the Rookie Roundup, it 
> developed a major problem.  I was on SSB and splattering all over the place.  
> I disable the pa deck, and set the power to 1W and I'm transmitting between 
> 20 and 30 watts, depending on the band.  All bands are 20 except for 40m 
> which is 30 watts.  I've made a few measuments of resistance and voltage, but 
> so far everything seems fine.  It receives fine, and works correctly in every 
> other way.  I also tried it in tune mode, and with a CW key, and I get the 
> same results.  I did purchase some coax a while back, that gave me fits for 
> quite some time, I finally figured out, the center pin was shorted out to the 
> shield.  I replaced the ends, and everything was working great.  I haven't 
> used it much between then and now, so it may be a contributing factor. Will 
> you recommend what I can do to narrow
>  down the problem?
> 
> 
> 
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