[Elecraft] L34 on K2 tuning question?

[Kevin Cozens]

Eddy Avila wrote:
> Changes while tuning L34 on my K2 are very subtle.
> Just barely hear L34 peak with the slug near the top
> of the can....is this normal?
> 
> I'm just trying to determine if the receiver on my K2
> is working as it should.

I recently went through a similar situation where I felt my K2 was not hearing 
as well as it was supposed to be hearing. After checking for construction 
problems, I went back over the alignment including re-adjusting L34. I came up 
with a little tip on how to make adjusting L34 a little bit easier.

As you are probably aware, adjusting L34 is best done with Spectogram. It is 
very difficult to tell when you have the maximum strength on the internal 
signal with the lowest noise just by ear.

Take a look at the screen capture I made (http://www.ve3syb.ca/tmp/K2-L34.jpg) 
while adjusting L34 on my K2. You will notice there are two cross style 
cursors, one in red and the other in black.

Once you have the K2 set up and Spectogram ready to go (ie. you see the 
internally generated signal), move the cursor so the horizontal part of the 
cursor is just at the top of the internal signal (the black cursor) and left 
click with the mouse to mark the level. Next, move the cursor to the top of 
the noise floor (red cursor) but do not click with the mouse.

You can now easily watch for changes in the level of the internal signal while 
watching the noise floor. When adjusting L34, this set up made it easy to see 
when the internal signal was at its peak. You can left click with the mouse 
during the procedure to move the cursor that indicates the level of the 
internal signal as needed (ie. as it starts to get stronger) so you can tell 
when you have hit the peak remembering to move the cursor back to the top of 
the noise floor afterwards.

When adjusting L34 on my machine, I was easily able to see when the internal 
signal was strongest. While adjusting L34 I never saw a change in the level of 
the noise to the left of the signal. After the internal signal peaked, 
adjusting L34 so it went further in to the can meant that the signal to the 
right of the internal signal began to drop off at a sharper angle. On my K2, 
the slug seems to have bottomed out and makes me wonder if a cap needs to be 
changed so the optimum setting of L34 will be with the slug somewhere in the 
middle of its range of travel.

I hope the idea about positioning the cursors to aid in detecting changes in 
levels of the internal signal and the noise floor might be useful either to 
you or to other people.

PS. I have discovered that Spectogram seems to work when run under Linux via Wine.

-- 
Cheers!

Kevin.

http://www.ve3syb.ca/           |"What are we going to do today, Borg?"
Owner of Elecraft K2 #2172      |"Same thing we always do, Pinkutus:
                                 |  Try to assimilate the world!"
#include <disclaimer/favourite> |              -Pinkutus & the Borg