[Elecraft] K2 Alignment & Test Part 1

[Joe - aa4nn]

My follow-up with Michael's suggestions.
73, Joe, aa4nn

Michael:  So, what do you have at pin 1 of U8?
Me:  Pin 1 shows 5.1 volts with st l 255,  2.5 volts with st l 128

Michael:   The voltage on the drain of Q5 will show about half
that if Q5 gate is driven with a square wave signal from U8 pin 4.
Me:  At RP7 pin 6 (drain?) is zero volts.

Michael:  The signal from U8 pin 4 should be about 2.5 VRMS AC.
Me:  zero volts

Michael:  Toggle side tone source if this is not true.
Me:  Toggle has no effect.  I left it at U8-4.

Michael:  If U8 pin 1 is 0 Volts DC, and U8 pin 4 does not AC on it, and =
you have
met all of the menu conditions to get a side tone, start looking for bad
connections around about U8.

Me:  I inspected all around U8.  Some solder did not flow around some =
pins on the component side of the board.  I added solder to ensure flow =
through.  I will continue looking for bad connections.

Michael:  Note that if you inject a little DC current into the drain of =
Q5, you
should hear a pop in the speaker as you connect it.  A 47 K Ohm resistor
from the drain to the 5 volt supply should do it.  If you hear side tone
at that point, the problem is with the volume control out of pin 1 on =
U8.

Me:  U8-1 seems to be okay. =20

73, de Michael, AB9GV

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