[Elecraft] K3 Hum on Audio...

[riese-k3djc at juno.com]

so you unplug the mike input to K3 the hum goes away
when you plug into the K3 mike input the hum is there ?
I would think you have a bad mike/cord/connecter

Bob K3DJC

On Fri, 13 Jan 2012 11:31:38 -0800 Phil Hystad <phystad at mac.com> writes:
> 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
> > 
> 
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