[Elecraft] P3 - KXV3 Gain Mod Question

[Don Wilhelm]

Fred,

Look at that mod on the Elecraft website - click on the K3 Mods + 
Application Notes.
There you will find that the mod has been included on all new K3s since 
about 9/01/2009.
If your K3 is older than that, the mod is needed - if it is quite near 
that date, then you should do the test indicated with the mod 
instructions to see if it is installed or not.  If it is significantly 
later than 9/01/2009, then the mod is already installed.

You only need to remove the front bottom cover to check or install the mod.

Yes, you need it for proper (calibrated) operation with the P3, and it 
is shipped with every P3, so some obtain the part even though it may not 
be needed.
If your K3 does not have the change, by all means make it - it is not 
difficult - alternately heat the ends of the installed resistor until it 
comes free - wick away the left-over solder from one solder pad - hold 
the resistor on place gently with tweezers or other suitable tool and 
heat first the end where you did not remove the old solder, then apply 
solder to the other end - check for continuity from both ends of the new 
resistor to the associated solder pad - if zero ohms, job is done - if 
not, resolder the offending end.

73,
Don W3FPR

On 9/12/2011 6:17 PM, Fred Jensen wrote:
> Had a nice QSO with Dwayne, KE5EFY this AM and got quite a bit of my new
> P3 set up.  It appears to me that everything is working as it should, I
> got S-units to appear on the ordinate [they mean more to me than dBm on
> HF], got a few Fn switches set, and he walked me through the PEAK/NOT
> PEAK toggle.
>
> When I started building, I installed the KXV3 first, and had the K3 back
> on the air before I started the P3.  In the P3 stuff, there was an "IF
> Gain Mod," change one resistor on the K3 RF board.  I had already
> re-installed the countable infinity of chassis screws into the K3, and
> screwing around with an SMD the size of a grain of pepper didn't really
> "light my fire," so I put it aside.  Now, with everything working just
> fine, I'm wondering what that mod really does?  Do I need it?
>
> Incidentally, while installing the KXV3, I needed to cut jumpers W1 and
> W2.  This is easier said than done.  They are right up against a board
> that I wasn't told to remove.  I did finally get them cut with the very
> end of a small pair of scissors.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2011 Cal QSO Party 1-2 Oct 2011
> - www.cqp.org
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