[Elecraft] BFO/PLL Mods Comments

[Tom Hammond NØSS]

Good Morning Everyone...

Yesterday afternoon, I made the BFO/PLL mods to my Field Test K2.

I thought it might be appropriate to make a few comments upon my 
observations, having now actually DONE the mod..

First of all, the mod went well. However I must admit that it went MUCH 
more smoothly as a result of having access to a good solder sucker.

1) Confirming the component removal instructions I wrote in the mod 
document, I did find that it was easier to first remove the component lead 
from the PC board and THEN clean out the hole later.

ONCE THE JOINT HAS BEEN HEATED AND THE SOLDER IS MOLTEN, a slight upward 
pull on the lead should allow it to be removed with little stress or strain 
on either the component OR the PC board itself.

Note that if you pull too hard or if you pull before the joint is ready, 
you CAN lift the PC board land closest to the component.

2) NOTE - THE FOLLOWING IS NOT ELECRAFT-APPROVED... and may NOT BE. However 
it will be tested to see if it is a safer method of attaching the tiny L33 
leads to the PC board. For now, the "OFFICIAL" Elecraft attachment method 
is to solder the leads to the leads of the 5M resistor once it has been 
installed. SO please understand that I am NOT advocating the use of the 
method I used (below). However IF you decide to try the method below, 
PLEASE, for the benefit of others, REPORT back to the reflector on your 
success/failure.

NOTE that Wayne just dropped me a message to say that this method may NOT 
be appropriate for builders of K2s with Rev B (serial numbers 300 and 
above) because he may have made the PC board holes a bit smaller. If so, 
I'll drop a note to confirm/deny this possibility.

I used a slightly different technique for ATTACHing the leads of L33. 
Before I installed the 5 Megohm resistor across L33, I inserted the #35 
wire leads of L33 into the PC board holes (leaving a small bit of 'slack' 
in the length of each lead so as not to put ANY stress on either lead. And 
then I installed the 5M resistor into the SAME holes. My PC board holes 
were well cleaned, so there is NO interference between the two wires in the 
same hole... still an adequate amount of 'wiggle room' available.

Once both wires were installed as described above, I held everything in 
place, and grabbed ONLY the leads of the resistor, pulled slightly, and 
bent them to the side to hold things in place.

I then soldered each connection.

I went back, grabbing (ONLY) the 5M resistor lead(s), exerted a bit of pull 
on it AS I reheated the joint. This allowed me to take up any 'slop' which 
might have crept in during soldering.

At this point I had the resistor securing L33 to the PC board and the L33 
leads remained with a bit of slack so they weren't stressed in any way.

I found that things were getting pretty 'tight' on the TOP of the RF board, 
especially when it came to 'close-clipping' of the 5M resistor and L33 
leads. The very LAST thing I wanted to do was to get in there (ham-handed 
that I am) and wind up clipping the WRONG lead or breaking something in the 
process.

To remove the excess lead length, I grabbed each INDIVIDUAL wire lead with 
a pair of needle-nodes pliers, pulled up on it just a bit and 'worked' the 
lead back and forth until it broke right at the soldered joint, leaving a 
nice, clean 'clipped' side.

3) When all was said and done (there was more said than done, by the way), 
the realignment went without event. I did notice that the 3-digit DAC 
values were quite a bit different than those recorded initially (using 2 
XTALs in the PLL). But the FREQUENCIES recorded early-on in the mod 
procedure appeared to be very close to those subsequently used. It took me 
about 6-7 minutes to complete realignment of all filters using 
Spectrogram... even though I DID record (and use) the original filter 
settings, I still wanted to confirm the final settings with Spectrogram.

I hope these observations my assist you in completing your mods.

73,

Tom Hammond   N0SS