[Elecraft] K2 5233 alignment problems

[Don Wilhelm]

Dan,

Whoa!!
One thing at a time please.
You apparently are having multiple problems.  That is not unusual for a 
new build.
BUT - take things one at a time, the anomalies are not likely to be 
related.  The K2 breaks down into neat functional units.  If you have 
trouble believing that, just look at the block diagram.  Start with the 
first block of the block diagram and verify its proper operation.  
Resist the temptation to go on to other items before that functional 
block is verified.  If you give in to that temptation, you will 
overwhelm and confuse those who are trying to help with extraneous 
information, and you will have a tendency to jump to conclusions that 
are not necessarily correct.

Lets take the first item - the loss of sidetone.  You likely have 
firmware level 2.04P which allows a selection of the sidetone source 
between U6-25 and U8-4 to support older K2s.  For your K2, the source 
must be U8-4.  Enter the menu for ST-L and edit the parameter - set the 
level somewhere between 25 and 40, then tap DISPLAY to toggle the 
sidetone source.  When you hear sidetone, stop and exit the menu.

You may have to perform the steps listed in the Transmit Signal Tracing 
section of Appendix E in the K2 manual to determine the failing stage.  
Stop at the first one which does not fall into the expected range - all 
the measurements which follow that failing point will also be incorrect, 
so the first failing point is the one to concentrate on until resolved.

Please explain "improper voltages or double voltages" - especially the 
double voltages part.  I cannot understand what you mean by 'double 
voltages' - your measured voltages are your measured voltages, and there 
should be no ambiguity in that.  Please specify whether the voltages are 
DC measurements (made with your DMM) or RF voltages (measured with an RF 
Probe).

73,
Don W3FPR

kf4pob at aol.com wrote:
> I hear that a third time is a charm. This is the third time trying to post and I hope it works.
> I am at the alignment section of phase III and everything seems to have gone hay-wire. Phases I and II went well with only a couple of glitches that were corrected with your help. I checked and repaired a few solder joints, looked for solder bridges and correct parts in the correct locations and fired up the unit. No smoke and no overheating. I set the power out at 2 watts, unit at 7100 and hit the button to adjust L1 and L2. I had .2-.3 watts indicated but they did not fluctuate when adjusting the pots. I checked the diode and resisters that they said were easily reversed and they were all ok. Using the rf probe I had no voltage at either side of r50. Further checks of components in the transmitter section found most of the U chips had improper voltages or double voltages at the appropriate pinsl I then went back to phase I and started running checks again. All was ok until I got to the tone generator and pitch. I now had neither!. The display showed the values I had after t
>  he construction of that phase but now they are gone. When I hit the button to turn the tone on the audio went away. I did notice a very low click when I adjusted the vfo. I also went back to check the birdy at 7000 and found it to be very weak and totally disappeared when I moved the vfo dial. It came back when I hit the edit button but very shaky. 
> Logic dictates the problem is in the construction phase of part III. The above is a short synopsis of the checks I did but I did not take the time to give the actual values of the U pin voltages at this time. I have tried to post twice before and want to verify this message goes thru before taking the time to enter the values. This leads to two questions
>
> 1)? Where do you suggest I start from here?
> 2)? Is there anywhere I can get a picture of the rf board before any parts are installed. That would be great for helping me locate any solder bridges on those small pads. 
>
> Thanks in advance for your help.
> Dan 
> af4lb
>   
>