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P3 - KXV3 Gain Mod Question

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k6dgw

P3 - KXV3 Gain Mod Question

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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Bill W4ZV

Re: P3 - KXV3 Gain Mod Question

<quote author="k6dgw">
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?
<\quote>

http://cliftonlaboratories.com/elecraft_k3_and_panadapters.htm

7r, Bill

Matt Zilmer

Re: P3 - KXV3 Gain Mod Question

You need it. Sorry.

73,
matt W6NIA
K3 #24

On Mon, 12 Sep 2011 17:51:30 -0700 (PDT), you wrote:

>
> 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?
><\quote>
>
>http://cliftonlaboratories.com/elecraft_k3_and_panadapters.htm
>
>7r, Bill

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Greg - AB7R

Re: P3 - KXV3 Gain Mod Question

In reply to this post by k6dgw

Fred. An all important question... what is the see number of your K3?

73
Greg
On Sep 12, 2011 3:17 PM, "Fred Jensen" <[hidden email]> 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

Re: P3 - KXV3 Gain Mod Question

In reply to this post by k6dgw

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: