[Elecraft] K2 question/new owner

[Don Wilhelm]

Don,

Welcome to the Elecraft list.  You must be posting properly, your post 
made it to the list.

When you hold the TUNE button, there is only a brief 'beep' not a tone.

During a TUNE, the basic K2 (no KAT2) displays the power output as 
measured with a simple diode RF detector.  That power level will only be 
correct if the K2 is operating into a load impedance of 50 ohms pure 
resistive.  The variation as you move across the band is due to 
variation in the actual impedance of your antenna as seen at the shack 
end of your transmission line.

But OTOH, the K2 will attempt to control power at whatever level is set 
on the Power 'requested' knob, so if you are set to 10 watts, the K2 
will try to adjust the drive until the RF voltage from the RF detector 
is equal to that power level driven into a 50 ohm pure resistive load.  
SWR into your feedline will affect the actual power developed by the 
K2.  An 80 meter antenna will have a significant change in SWR over the 
band.  You may have to retune the Z100 frequently when moving across the 
band to allow the K2 to properly control the power.

For tuning your Z100, holding the TUNE button will transmit at whatever 
power level is set on the power knob, so the maximum power that your 
Z100 tuner should have during a tuning cycle sets the limit.  Set that 
power level with the Power knob.  After tuning, set the power to your 
desired operating power.  During the time the Z100 is tuning, the power 
out indication may vary all over the board as the SWR is constantly 
changing while the tuner seeks a low SWR.

The addition of a KAT2, KPA100 or KAT100 will provide better power 
control with your K2 because those options contain wattmeters (as 
opposed to a simple RF voltage detector) which remove the SWR dependency 
from the power control operation.

The bottom line of all this is that the K2 controls power differently 
than your prior transceivers.  The K2 tries to measure the actual RF 
output and computes what it 'thinks' is the power into a 50 ohm 
resistive load, then adjusts the drive to bring the output up to what 
you have requested.  Most other transceivers simply adjust the drive to 
the PA and let it go at that.

With the antenna that you have, you should consider the addition of the 
KAT2 (or if you are considering a future addition of the KPA100, use the 
KAT100),  The built-in wattmeter make tuning antennas much easier.

73,
Don W3FPR


On 3/10/2013 8:20 AM, bukar wrote:
> I hope that I am posting this properly, if not please correct me. :-)
>
> I am the new owner of K2/10 #5001. I am more used to tuning up the hybrid Kenwoods so while I am looking forward to moving to this more modern radio I have some questions.
>
> I think that I must have toggled something off as I no longer can get a tone when I push the "tune" switch on and off. It was working but I was in the menus and fear I have done something to cause this.  I can't find the page in the manual to correct this. Any suggestions?
>
> Also, when I tune the radio with my LDG z100 tuner  should I dial back the power on the rig to 3-2 watts before tuning, get a match and then go back to 10 watts?
>
> I don't understand the read out I get on the display.  The Po number that is displayed after the tune up, is that the recommended max power to use at that particular match? I am trying to keep my power out to 10 watts but some matches even a few kelos apart will display a Po reading from 15 to >5 as I tune across the band.
>
> I am using the rig SSB into a 80 meter dilpole at 40 feet.
> 73
> Don Bukar
> KJ4RQV
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