[K3] 1.0 Milliwatt Calibration

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[K3] 1.0 Milliwatt Calibration

Tony Scesny
Julian,

  I think you are using the wrong formula.   The DL1 formula posted is
not correct.  I'm kinda jumping in here for Don.  He posted the
correction on May 9 2009 see [Elecraft] L1 vs W1 Power Reading.  The
correct formula is (Vdmm + Vdiode) ^2 /25.  You can assume the diode
drop is 0.3 volts.  I don't think this has been corrected in the DL1
manual.  However, the graph shown appears to be correct.

    As a side note regarding  Power Calibration.   The use of the DL1 is
a very valuable tool to use in adjusting the WMTR  LP/HP   settings.  
The part that MAY be responsible for Power settings not being what they
should be is,  they vary from band to band depending upon the impedance
of the Dummy Load used,  and you may want to interpolate between the
high and low readings for a general calibration.  Also,  I found that
when adjusting  LP and HP  to get the voltage reading on the DL1, the
voltage change is not linear.  Sometimes it takes two or three units of
change to have any affect on the voltage reading.  After changing these
settings, be advised to RE-RUN the 5 and/or 50 watt calibration so
that,  the new settings will be used to reset the power.  Once this is
done,  you might want to RE-CHECK the voltages readings on the DL1.  For
LP I use 10 watts  and  HP use 20 watts to stay within the ratings of
the DL1.  The LAST  of my notes,  I use a barrel connector to connect
the DL1  DIRECTLY to the back of the K3.  NO COAX  involved.

73 ,
Tony Scesny  K2ZLS
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