[Elecraft] Ailing K2

[Don Wilhelm]

There is another mechanism in the MCU that helps do that, but it is not 
always effective - that is the CAL CUR setting.
It must be set to 3.50 Amps for a K2 with a KPA100, and often the K2 
will show HiCurr when the wattmeter diodes fail.
The problem I see with that is many users continue to operate in spite 
of that warning.  The situation gets worse if the user turns the power 
knob to maximum.  I recommend that the power knob be set to no more than 
10 watts for the base K2 and no more than 100 watts with the KPA100.  
Your signal will be cleaner on the bands and the power control will be 
smoother.
If you "do the math", you will find only a miniscule difference between 
100 watts and 120 watts at the receiving end.  So why stress your 
equipment by squeezing that last ounce of power out if it.  I know, 
historically hams have tried to get all they can out of a device, and 
may not think of the stresses involved in that process.

There is another thing to watch to keep your Elecraft K2 or K3 or KX3 
transceiver running with less stress, and that is to keep the power 
supply voltage up.  There is less stress on the components when using a 
14.4 volt power source than when running at 12 volts. Your signal IMD 
will be better with the increased voltage as well. The reason is that 
the K2, K3, and KX3 attempt to maintain the requested power - for any 
given power level, if the voltage is increased, the current will be 
reduced.  It is typically current that kills solid state devices in any 
proper design.

73,
Don W3FPR

On 4/18/2013 8:42 AM, Greg Troxel wrote:
> Don Wilhelm <w3fpr at embarqmail.com> writes:
>
>> What normally happens with a static surge on the antennas is that the
>> wattmeter diodes fail, and that causes the K2 to not sense the power
>> output - the MCU in the base K2, thinking there is no power output,
>> cranks up the drive to maximum possible, and that stresses the PA in
>> the base K2.
> Maybe this is too complicated, but perhaps the MCU could check for there
> being a reasonable partial derivative from drive to perceived output,
> and if not decline to increase drive, so that the secondary finals
> damage could be avoided?
>