[Elecraft] K3 Hum on Audio...

[Phil Hystad]

Ron,

Well, I just had a quick SSB chat with Clyde (AA7WC) (pre Noon Time net on 40 meters) and asked specifically for audio report with possible hum.  His report was no hum, clear good sounding audio, with S7 signal.

So I am suspicious of my florescent lights in the garage although they are on right now with no hum.  I am thinking though that maybe there is something intermittent with those lights.  But, then again, the "something loose in the mic cord" maybe be the cause too.  But, I jiggled that cord and connection and so on quite vigorously before when I had the hum and it did not change the hum status.  Then, when the hum disappeared, I did those jiggle the cord and connector on the mic tests again and the hum DID NOT come back.

Wow, I can't believe I have spent the entire morning fooling around with this.  I even called into work and said that I was not coming in today just to work on this problem.  I don't really want to go outside anyway despite that the temperature has now risen to a toasty 36 degrees.

73, phil, K7PEH


On Jan 13, 2012, at 11:23 AM, Ron D'Eau Claire wrote:

> Good luck Phil. That last part really suggests something loose in the mike
> cord as I suggested at first. 
> 
> Ron AC7AC
> 
> -----Original Message-----
> Ron,
> 
> OK, now it appears I was mistaken when I said that that the hum was in both
> mics.  I think I flubbed something up in my previous test due to the way
> that the macros are assigned to keys which led me to thinking that the hum
> occurred in both mics.   But, I learned something in this...
> 
> One, don't try to use one of your macro assigned keys (in my case M2 and M1)
> while in the menu because that merely reassigns the key to the new menu
> entry.  I made this mistake several times this morning.  But, when I
> discovered it and then reset my macro definitions, I rediscovered that the
> HUM occurs in the front panel MH2 hand held mic only.  I did this test
> several times to make sure I was not confusing things.
> 
> I discovered something else that I did not know before.  PTT is actuated by
> any of the methods of PTT.  So, when I thought I had the headphones CM500
> mic enabled I used my foot switch for push to talk and since that worked for
> some dumb reason I was thinking I had successfully switched from front panel
> to rear panel.  But, I had not.  I also discovered that I could use the hand
> mic (front panel) PTT switch even though my rear panel mic was being used.
> Now, after I discovered this, I realize that it is obvious but something
> that lead to my confusion.
> 
> So, the problem occurs on the FRONT PANEL mic only and not the rear panel.
> And, the problem occurs when the K3 is in TOTAL isolation from all AC
> sources except for possibly me.  I mean, I am holding the mic but then I
> don't think that is a cause of the hum because I tried it with a insulated
> hand and it still caused the hum on the front panel mic.
> 
> I doubt that this is caused by wall-outlet type AC because I have erased all
> AC for some of my tests.  And, besides, this problem seemed to occur ....
> 
> OK, while writing that last sentence something occurred to me.  Another
> change I had made on Wednesday after I had my good audio reports on the MH2
> front panel mic was that I set the configuration for the band specific power
> levels to work with the KPA500.  So, I just now went to test the mic and
> change that setting around but the hum is gone.
> 
> I repeat, the hum is gone from the front panel mic.   I now can't test the
> band specific power menu setting because I have no problem.
> 
> But, I have a suspicion as to the cause now and I am going to do some other
> experiments.
> 
> 73, phil
>