[Elecraft] K1 continued... sidetone

[David L DuPuy]

Don and Mike,

1)  the LCD does indeed show FL1, FL2, FL3 in sequence as the XFIL button
is held down in sequence.

2)  I could not see a significant change in voltage on FP U2 pin 1 (OUTA)
as the XFIL is held.  It was not very stable, but fluctuated from 0.18 to
0.22, regardless of the filter width selection.

3)  I pulled the front panel and checked the resistance from FP U2 pin 1 to
ground, and it measures 3.7 megohms.  I checked the ground on pin 7, and
that's a good ground.  And I checked RF P1 pin 5 to ground (RF board) and
that measures around 3.5 megohms.

4)  Finally, I checked the continuity from FP U2 pin 1 to the input side of
RF C72 in the audio section, and that read 0.1 ohms.

I assume a new MCU is more than just a couple of bucks?  But maybe that's
the next step.  I don't know anyone with a K1, and I live in a small town
in the western part of Virginia, so finding an MCU to try out is tough.
 Cheaper to order a new one, I guess.

Since the same control lines (SDA and SCL) run to both U2 and U3, and we
see no evidence that U3 is misbehaving (and POWER setting on U2 works
fine), does that argue that the MCU is okay?  I assume that settings, such
as frequency calibration, are stored in the EEPROM?  I've never seen that
change, except today when I reset to factory defaults and then
recalibrated.  Other settings such as STP have always stored correctly.
 Many thanks for your help,  David