[Elecraft] K2 RF Board Test II

[Don Wilhelm]

John,

The VCO frequency of 8903 kHz is not correct for the 40 meter band.

I would be willing to wager that you have installed the 'Rework Eliminators'
which includes the changes to the RF Board for the K60XV.

The K2 manual clearly states that one should NOT install the K60XV
components until the K2 has been properly tested, but it seems the
instructions from the Rework Eliminator guys ignore that and just say to 'do
it anyway'.

Since you have already installed the 120 pf cap for C71 and installed D19
and D20, you will have to operate it as if the K60XV is installed, so set
the D19 parameter in the menu to ON and then re-run CAL PLL and CAL FIL as
instructed in the K2 manual.

You are not able to properly check the VCO range (voltage at R30) at the
critical points until you actually install the K60XV, so just check all band
edges to be certain they are within range and make a mental note to re-check
those VCO ranges after installing the K60XV option.

Don't be overly concerned about the voltages at those pins of U6, U7 and
U8 - these are digital signals and if the K2 display and front panel buttons
are working properly, those signal paths are likely just fine - there is
confusion over whether the high or low state should be listed in the DC
Voltage Chart, because the conditions to produce each reading are not always
present.
73,
Don W3FPR


  -----Original Message-----


  Hi, Don, and tnx for the reply.

  Here are the values that I got:

  PLL            12098.74
                     12086.09
  range                 12.65

  VCO           8903.42

  BFO           4913.61

                     4917.06
                     4912.72
  difference          4.34

  I have done the PLL/VCO/BFO process three times now. They were consistent
each time.

  Since you mentioned the EEPROM, the trouble shooting section pointed to U7
on the Control Board. All voltages were correct except pin6 which was 5
volts instead to zero. Going forward and backward, U8 pin 6 on the RF Board,
and U8 pin10 on the Control Board, are both 5 volts instead of zero. I don't
know where to go from there.

  I truly appreciate your help and have observed on the list that you are
most knowledgeable. Elecraft said to do the CAL PLL and CAL FIL processes. I
have done them both multiple times, with no change in result.