[Elecraft] Re: Debate K2 Pro Align and Test Data Issue

[Wayne Burdick]

> The problem occurs if you follow the alignment instructions, and DON'T have
> a good radio. How do you know if the K2 you have built is "good" or
> "mediocre"?
> 
> Where is the problem?  Unless you have ac voltages, dc voltages, rf voltages
> or power levels specified at many PCB pads, you have no way of comparing
> what you observe in your radio, with what should be there.


I agree that additional data, for those who have access to professional test
equipment, could be compiled and added to our manuals or to application notes.
However, much of this data *is* already present in the manual. We believe that
what is supplied is sufficient to determine whether a K2 is working as specified.

For example:

Appendix E of the K2 manual lists all DC voltages on diodes, transistors, and
ICs, in both RX and TX mode where relevant, which covers about 90% of the tie
points in the radio. The option manuals provide similar data. This data was not
cross-listed on schematics. We found the tabled data easy to use and easier to maintain.

Appendix E also includes an extensive receive and transmit signal tracing
procedure that includes RMS voltages at all significant points in the signal
path. This is similar to what one finds in service manuals, which are generally
not supplied with commercial gear.

Further, the revision B K2 (shipping for months now) includes all of the parts
needed to assemble an RF probe with which to do signal tracing. The RMS voltages
listed are typical, based on use of the RF probe, rather than an oscilloscope.
(There is some difference between the two at low signal levels.) One can even
use the K2's built-in DMM along with the RF probe to measure all but the lowest
voltages. This is why we provided a DMM input connector on the Control board.

To make use of additional alignment data, one would need at minimum a very
well-calibrated microvolt-level signal generator, which is rare in a ham shack.
We've considered offering a simple crystal oscillator kit that would put out 1
microvolt and 100 microvolts RMS (+/- 10%) at a specific frequency. Further
suggestions for low-cost test gear are always welcome.

In the vast majority of cases where a component is defective, unsoldered, or the
wrong value, performance degradation will be obvious, especially if one follows
the signal tracing procedure.

We certainly welcome third-party efforts to characterize the K2 and publish the
resulting data.

73,
Wayne
N6KR