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K3 IF Mod - Is it needed or not?

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K4SC

K3 IF Mod - Is it needed or not?

I have K3 #3332 which I built in August of last year (I think). I also have P3 #302. I am not sure whether my K3 has the IF output mod already installed or not. I believe the transition was September. Is there anyway to definitively tell whether or not I have it? My P3 seems to "see" signals just fine. As an example, just now on 40 meters noise seems to be centered at approximately -115 dbm with my vertical connected and -125 when I switch to Antenna 2, which is not connected. Does that sound about where it should be. I really do not want to alter the PC board on my K3 for no reason. Your comments would be appreciated. Chuck K4SC.

Bill W4ZV

Re: K3 IF Mod - Is it needed or not?

K4SC wrote

I have K3 #3332 which I built in August of last year (I think). I also have P3 #302. I am not sure whether my K3 has the IF output mod already installed or not. I believe the transition was September. Is there anyway to definitively tell whether or not I have it? My P3 seems to "see" signals just fine. As an example, just now on 40 meters noise seems to be centered at approximately -115 dbm with my vertical connected and -125 when I switch to Antenna 2, which is not connected. Does that sound about where it should be. I really do not want to alter the PC board on my K3 for no reason. Your comments would be appreciated. Chuck K4SC.

Remove the bottom front panel on the K3. Look for R8 as shown in the photos here:

http://www.elecraft.com/K3/mods/IF_Output_Buffer_Gain_Mod_Rev_A.pdf

If you see "133" marked on R8, the value is correct and the mod is not necessary. The mod makes ~10 dB sensitivity improvement which might not be noticeable on 40m with the atmospheric noise we have now.

73, Bill

K4SC

Re: K3 IF Mod - Is it needed or not?

Thanks Bill, I'll do that.

--- On Fri, 9/3/10, Bill W4ZV [via Elecraft] <[hidden email]> wrote:

From: Bill W4ZV [via Elecraft] <[hidden email]>
Subject: Re: K3 IF Mod - Is it needed or not?
To: "K4SC" <[hidden email]>
Date: Friday, September 3, 2010, 11:16 AM

K4SC wrote:

I have K3 #3332 which I built in August of last year (I think). I also have P3 #302. I am not sure whether my K3 has the IF output mod already installed or not. I believe the transition was September. Is there anyway to definitively tell whether or not I have it? My P3 seems to "see" signals just fine. As an example, just now on 40 meters noise seems to be centered at approximately -115 dbm with my vertical connected and -125 when I switch to Antenna 2, which is not connected. Does that sound about where it should be. I really do not want to alter the PC board on my K3 for no reason. Your comments would be appreciated. Chuck K4SC.

Remove the bottom front panel on the K3. Look for R8 as shown in the photos here:

http://www.elecraft.com/K3/mods/IF_Output_Buffer_Gain_Mod_Rev_A.pdf

If you see "133" marked on R8, the value is correct and the mod is not necessary. The mod makes ~10 dB sensitivity improvement which might not be noticeable on 40m with the atmospheric noise we have now.

73, Bill

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