[Elecraft] K3 Hum on Audio...

[Phil Hystad]

When the sun rose today and it seems that my K3 decided to put some hum on my 
audio.  During a quick SSB contact tonight on 80 meters I was told there was 
hum on my audio.  This surprised me because yesterday I was involved in two 
different SSB QSOs where I was particularly interested in audio reports because 
I had just put the KPA500 on the air and wanted to know how it sounds.  The 
audio reports yesterday, two different QSOs, were excellent.  In fact one 
person wanted to know the rig because he said it sounded exceptional.

Well, tonight, I get a report of what sounds like (the other guy reported) 60 
cycle hum on my audio.  Now, absolutely NOTHING is different from yesterday, 
same configuration and all.  So, I am thinking maybe it has something to do 
with the KPA500.  So, I put that in Standby and the hum is still there on the 
audio.  The mic is the MH2 hand mic plugged into the front of the K3.

So, I switch to my Yamaha CM500 headset and mic plugged into the rear of the 
K3.  No hum on that.  So, the hum seems to do with the MH2 or maybe the front 
panel connection or something else.

Does anyone know of what would cause this sudden thing and where I might go to 
scope out the problem?  I would be more suspicious if it were some rig that was 
new to me, or some mic that was new or something.  But, it is not new and until 
now I have always had excellent reports.  Like I said, yesterday the KPA500 was 
put on the air for the first time but the reports were excellent reports on 
audio, this problem appeared today in fact, about 30 minutes ago.  I turned the 
rig on at 6:15 PM and had the first QSO where the hum was reported at 6:25 PM.

73, phil, K7PEH

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Re: [Elecraft] K3 Hum on Audio...

[Ron D'Eau Claire]

Since it goes away when changing mics, it sounds a lot like a broken
connection in the microphone connector. I used to fix those by the dozens on
shipboard VHF radios, equipped with hand-held mics. The complaint would be
transmitting hum, no audio, or no PTT action, depending upon which wire
broke. 

Usually the break was at the connector, but sometimes it's in the mic,
depending upon which end had the best strain relief. Even found a broken
wire inside the cable on rare occasions. 

73,

Ron AC7AC

-Original Message-
Subject: [Elecraft] K3 Hum on Audio...

When the sun rose today and it seems that my K3 decided to put some hum on
my audio.  During a quick SSB contact tonight on 80 meters I was told there
was hum on my audio.  This surprised me because yesterday I was involved in
two different SSB QSOs where I was particularly interested in audio reports
because I had just put the KPA500 on the air and wanted to know how it
sounds.  The audio reports yesterday, two different QSOs, were excellent.
In fact one person wanted to know the rig because he said it sounded
exceptional.

Well, tonight, I get a report of what sounds like (the other guy reported)
60 cycle hum on my audio.  Now, absolutely NOTHING is different from
yesterday, same configuration and all.  So, I am thinking maybe it has
something to do with the KPA500.  So, I put that in Standby and the hum is
still there on the audio.  The mic is the MH2 hand mic plugged into the
front of the K3.

So, I switch to my Yamaha CM500 headset and mic plugged into the rear of the
K3.  No hum on that.  So, the hum seems to do with the MH2 or maybe the
front panel connection or something else.

Does anyone know of what would cause this sudden thing and where I might go
to scope out the problem?  I would be more suspicious if it were some rig
that was new to me, or some mic that was new or something.  But, it is not
new and until now I have always had excellent reports.  Like I said,
yesterday the KPA500 was put on the air for the first time but the reports
were excellent reports on audio, this problem appeared today in fact, about
30 minutes ago.  I turned the rig on at 6:15 PM and had the first QSO where
the hum was reported at 6:25 PM.

73, phil, K7PEH

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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

Ron,

I have been able to do more tests.  Unfortunately, it is in both mics but not 
as strong in the Yamaha CM500 mic as in the MH2 but it is present.

This morning I double checked all connections (most in the back).  This 
includes the key out to the KPA500, the plugs for the cm500, the external 
speaker, my foot PTT switch, and even the svga cable to the KPA500.  Nuts, have 
not tested the serial port yet.  However, absolutely no difference in behavior. 
  I can hear the hum on the speaker when I have the monitor gain cranked up a 
little bit and keying the mic in Test mode.

If I lay my hand on the top of the K3 the hum disappears.  If I lay my hand on 
the P3 sitting next to K3 the hum disappears but not as much.  And, I can do 
the same with other grounded equipment.  I have checked my grounds and they all 
seem to be pretty good.

So, I am at a loss as to what to try next.  This seemed to start on its own 
Wednesday afternoon after my last SSB QSO.  I say that because after that QSO, 
I turned the rigs off and then the next day (Thursday, yesterday) I turned the 
rigs on and the hum was there on my first SSB QSO at 6:30 PM.

It sure seems like a grounding problem but I am not sure where to check next.  
Also, this problem arose mysteriously close to me setting up the KPA500 which I 
put on the air for the first time Wednesday early afternoon, CW first and then 
a few SSB QSOs and I got good audio reports from both of those QSOs.  The hum 
though is definite, if someone were listening to my audio with this hum they 
would hear it.

73, phil, K7PEH


On Jan 13, 2012, at 8:12 AM, Ron D'Eau Claire wrote:

> Since it goes away when changing mics, it sounds a lot like a broken
> connection in the microphone connector. I used to fix those by the dozens on
> shipboard VHF radios, equipped with hand-held mics. The complaint would be
> transmitting hum, no audio, or no PTT action, depending upon which wire
> broke. 
> 
> Usually the break was at the connector, but sometimes it's in the mic,
> depending upon which end had the best strain relief. Even found a broken
> wire inside the cable on rare occasions. 
> 
> 73,
> 
> Ron AC7AC
> 
> -----Original Message-
> Subject: [Elecraft] K3 Hum on Audio...
> 
> When the sun rose today and it seems that my K3 decided to put some hum on
> my audio.  During a quick SSB contact tonight on 80 meters I was told there
> was hum on my audio.  This surprised me because yesterday I was involved in
> two different SSB QSOs where I was particularly interested in audio reports
> because I had just put the KPA500 on the air and wanted to know how it
> sounds.  The audio reports yesterday, two different QSOs, were excellent.
> In fact one person wanted to know the rig because he said it sounded
> exceptional.
> 
> Well, tonight, I get a report of what sounds like (the other guy reported)
> 60 cycle hum on my audio.  Now, absolutely NOTHING is different from
> yesterday, same configuration and all.  So, I am thinking maybe it has
> something to do with the KPA500.  So, I put that in Standby and the hum is
> still there on the audio.  The mic is the MH2 hand mic plugged into the
> front of the K3.
> 
> So, I switch to my Yamaha CM500 headset and mic plugged into the rear of the
> K3.  No hum on that.  So, the hum seems to do with the MH2 or maybe the
> front panel connection or something else.
> 
> Does anyone know of what would cause this sudden thing and where I might go
> to scope out the problem?  I would be more suspicious if it were some rig
> that was new to me, or some mic that was new or something.  But, it is not
> new and until now I have always had excellent reports.  Like I said,
> yesterday the KPA500 was put on the air for the first time but the reports
> were excellent reports on audio, this problem appeared today in fact, about
> 30 minutes ago.  I turned the rig on at 6:15 PM and had the first QSO where
> the hum was reported at 6:25 PM.
> 
> 73, phil, K7PEH
> 
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Re: [Elecraft] K3 Hum on Audio...

[Jim Brown]

On 1/13/2012 9:20 AM, Phil Hystad wrote:
> Unfortunately, it is in both mics but not as strong in the Yamaha CM500 mic 
> as in the MH2 but it is present.

Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly 
harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field 
coupling into the audio, either from a big power transformer (like the 
one in a power amp or a big linear power supply) or from a AC power 
wiring fault called a double-bonded neutral.

The K3 has unshielded audio transformers at all the audio inputs and 
outputs, and an unshielded transformer is a sitting duck for magnetic 
fields.

The good news is that the K3 has excellent audio equalization (TXEQ) 
that allows us to remove that 60 Hz hum by filtering.  The lower audio 
frequencies in the human voice make NO useful contribution to speech 
intelligibility, but they do waste transmit power. So it is ALWAYS a 
good thing to set the TXEQ for maximum cut of the lowest two bands, and 
at least some cut of the third band. This is true with virtually ALL 
mics and ALL voices.  AND it will reduce that hum enough that you may no 
longer hear it.

There are several solutions to magnetic field coupling.  1) Rotate the 
noise source or the victim circuit to put the fields at right angles to 
the victim.  2) Move the noise source further from the victim. 3) If the 
hum field is produced by that AC power wiring error, fix the error to 
eliminate the field.

73, Jim K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

Jim,

Well, I would call it mostly a buzz.  Also, the only near magnetic field of the 
KPA500 power transformer is off, I mean powered off and unplugged, so that does 
not seem to be the problem.

I just ran another test with everything disconnected, including ground and 
coax.  With the K3 in TEST mode, key-down on the mic still produces the hum.  I 
double checked the grounds.  I did this because if I were to touch anything 
metal on the k3, the metal part of the PL259 or the ground strap, the hum is 
damped quite a bit to almost insignificant.  It seems that if my rig were 
already well grounded this would not happen so I am curious if this is 
something I would normally expect.

I will experiment with the TXEQ but this is a real puzzle I would like to 
solve, not merely erase it.  

73, phil


On Jan 13, 2012, at 9:37 AM, Jim Brown wrote:

> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500 mic 
>> as in the MH2 but it is present.
> 
> Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly 
> harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field 
> coupling into the audio, either from a big power transformer (like the 
> one in a power amp or a big linear power supply) or from a AC power 
> wiring fault called a double-bonded neutral.
> 
> The K3 has unshielded audio transformers at all the audio inputs and 
> outputs, and an unshielded transformer is a sitting duck for magnetic 
> fields.
> 
> The good news is that the K3 has excellent audio equalization (TXEQ) 
> that allows us to remove that 60 Hz hum by filtering.  The lower audio 
> frequencies in the human voice make NO useful contribution to speech 
> intelligibility, but they do waste transmit power. So it is ALWAYS a 
> good thing to set the TXEQ for maximum cut of the lowest two bands, and 
> at least some cut of the third band. This is true with virtually ALL 
> mics and ALL voices.  AND it will reduce that hum enough that you may no 
> longer hear it.
> 
> There are several solutions to magnetic field coupling.  1) Rotate the 
> noise source or the victim circuit to put the fields at right angles to 
> the victim.  2) Move the noise source further from the victim. 3) If the 
> hum field is produced by that AC power wiring error, fix the error to 
> eliminate the field.
> 
> 73, Jim K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Barry N1EU]

Jim Brown-10 wrote
> 
> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500
>> mic as in the MH2 but it is present.
> 
> The K3 has unshielded audio transformers at all the audio inputs and 
> outputs, and an unshielded transformer is a sitting duck for magnetic 
> fields.
> 

I'm fairly certain that there are no transformers being used on the mic
inputs, only the line input (mono) and line outputs (stereo).

Barry N1EU


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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

I just did one more test.  I hooked up my little 4-cell Li nano-phosphate 
battery to the input.  Turned on the K3 and did the test again with the K3 in 
TEST mode.  Same hum occurs.  With this experiment, the only thing plugged into 
the K3 is the MH2 microphone itself and all AC in the room is switched off at 
the breaker.  So, K3 on battery and it still has this hum.  This is a bit 
perplexing.  I am writing here on my laptop which is battery powered too.

73, phil


On Jan 13, 2012, at 9:37 AM, Jim Brown wrote:

> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500 mic 
>> as in the MH2 but it is present.
> 
> Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly 
> harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field 
> coupling into the audio, either from a big power transformer (like the 
> one in a power amp or a big linear power supply) or from a AC power 
> wiring fault called a double-bonded neutral.
> 
> The K3 has unshielded audio transformers at all the audio inputs and 
> outputs, and an unshielded transformer is a sitting duck for magnetic 
> fields.
> 
> The good news is that the K3 has excellent audio equalization (TXEQ) 
> that allows us to remove that 60 Hz hum by filtering.  The lower audio 
> frequencies in the human voice make NO useful contribution to speech 
> intelligibility, but they do waste transmit power. So it is ALWAYS a 
> good thing to set the TXEQ for maximum cut of the lowest two bands, and 
> at least some cut of the third band. This is true with virtually ALL 
> mics and ALL voices.  AND it will reduce that hum enough that you may no 
> longer hear it.
> 
> There are several solutions to magnetic field coupling.  1) Rotate the 
> noise source or the victim circuit to put the fields at right angles to 
> the victim.  2) Move the noise source further from the victim. 3) If the 
> hum field is produced by that AC power wiring error, fix the error to 
> eliminate the field.
> 
> 73, Jim K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Geoffrey Mackenzie-Kennedy]

When the KPA500 is in standby, I assume that its AC mains is still 
connected.  Have you tried pulling the KPA500's mains plug to narrow
the search?

Is your P3 sitting between the KPA500 and the K3?

73,
Geoff
LX2AO

On January 13, 2012, at 18:20 +0100, "Phil Hystad"  wrote:



> If I lay my hand on the top of the K3 the hum disappears.  If I lay my 
> hand on the P3 sitting next to K3 the hum disappears but not as much. 
> And, I can do the same with other grounded equipment.  I have checked my 
> grounds and they all seem to be pretty good.

and earlier

>> So, I am thinking maybe it has
>> something to do with the KPA500.  So, I put that in Standby and the hum 
>> is
>> still there on the audio.  The mic is the MH2 hand mic plugged into the
>> front of the K3.

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Re: [Elecraft] K3 Hum on Audio...

[george fritkin]

I would short all audio inputs to the K3 right at the connector input with 
everything disconnected except antenna.  Key up radio in SSB and see if audio 
buzz is still there.

This test pretty much isolates the K3

George, W6GF

Love my two K3s and awaiting my KX3



 From: Barry N1EU 
To:
Sent: Friday, January 13, 2012 9:58 AM
Subject: Re: [Elecraft] K3 Hum on Audio...
 

Jim Brown-10 wrote
> 
> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500
>> mic as in the MH2 but it is present.
> 
> The K3 has unshielded audio transformers at all the audio inputs and 
> outputs, and an unshielded transformer is a sitting duck for magnetic 
> fields.
> 

I'm fairly certain that there are no transformers being used on the mic
inputs, only the line input (mono) and line outputs (stereo).

Barry N1EU


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Re: [Elecraft] K3 Hum on Audio...

[goldtr8]

Hi Phil,

I am no expert by any stretch of imagination if you follow my posts from 
my previous problems.

So please take what I have to say as only a suggestion.   Are all your 
external equipment grounds to a single point, this was major improvement 
in my shack.  What I mean by single ground is the grounding lugs for 
every piece of equipment in my shack goes to one grounding point so 
everything should be at the same potential.

Others who understand this more than I do will correct the 
implementation I am suggesting if I don't have it quite right.

Cheers
Don



~73
Don
KD8NNU


On Fri, Jan 13, 2012 at 12:20 PM, Phil Hystad wrote:

> Ron,
>
> I have been able to do more tests.  Unfortunately, it is in both mics 
> but not as strong in the Yamaha CM500 mic as in the MH2 but it is 
> present.
>
> This morning I double checked all connections (most in the back). 
> This includes the key out to the KPA500, the plugs for the cm500, the 
> external speaker, my foot PTT switch, and even the svga cable to the 
> KPA500.  Nuts, have not tested the serial port yet.  However, 
> absolutely no difference in behavior.   I can hear the hum on the 
> speaker when I have the monitor gain cranked up a little bit and 
> keying the mic in Test mode.
>
> If I lay my hand on the top of the K3 the hum disappears.  If I lay my 
> hand on the P3 sitting next to K3 the hum disappears but not as much. 
> And, I can do the same with other grounded equipment.  I have checked 
> my grounds and they all seem to be pretty good.
>
> So, I am at a loss as to what to try next.  This seemed to start on 
> its own Wednesday afternoon after my last SSB QSO.  I say that because 
> after that QSO, I turned the rigs off and then the next day (Thursday, 
> yesterday) I turned the rigs on and the hum was there on my first SSB 
> QSO at 6:30 PM.
>
> It sure seems like a grounding problem but I am not sure where to 
> check next.  Also, this problem arose mysteriously close to me setting 
> up the KPA500 which I put on the air for the first time Wednesday 
> early afternoon, CW first and then a few SSB QSOs and I got good audio 
> reports from both of those QSOs.  The hum though is definite, if 
> someone were listening to my audio with this hum they would hear it.
>
> 73, phil, K7PEH
>
>
> On Jan 13, 2012, at 8:12 AM, Ron D'Eau Claire wrote:
>
>> Since it goes away when changing mics, it sounds a lot like a broken
>> connection in the microphone connector. I used to fix those by the 
>> dozens on
>> shipboard VHF radios, equipped with hand-held mics. The complaint 
>> would be
>> transmitting hum, no audio, or no PTT action, depending upon which 
>> wire
>> broke.
>> Usually the break was at the connector, but sometimes it's in the 
>> mic,
>> depending upon which end had the best strain relief. Even found a 
>> broken
>> wire inside the cable on rare occasions.
>> 73,
>>
>> Ron AC7AC
>>
>> -Original Message-
>> Subject: [Elecraft] K3 Hum on Audio...
>>
>> When the sun rose today and it seems that my K3 decided to put some 
>> hum on
>> my audio.  During a quick SSB contact tonight on 80 meters I was told 
>> there
>> was hum on my audio.  This surprised me because yesterday I was 
>> involved in
>> two different SSB QSOs where I was particularly interested in audio 
>> reports
>> because I had just put the KPA500 on the air and wanted to know how 
>> it
>> sounds.  The audio reports yesterday, two different QSOs, were 
>> excellent.
>> In fact one person wanted to know the rig because he said it sounded
>> exceptional.
>>
>> Well, tonight, I get a report of what sounds like (the other guy 
>> reported)
>> 60 cycle hum on my audio.  Now, absolutely NOTHING is different from
>> yesterday, same configuration and all.  So, I am thinking maybe it 
>> has
>> something to do with the KPA500.  So, I put that in Standby and the 
>> hum is
>> still there on the audio.  The mic is the MH2 hand mic plugged into 
>> the
>> front of the K3.
>>
>> So, I switch to my Yamaha CM500 headset and mic plugged into the rear 
>> of the
>> K3.  No hum on that.  So, the hum seems to do with the MH2 or maybe 
>> the
>> front panel connection or something else.
>>
>> Does anyone know of what would cause this sudden thing and where I 
>> might go
>> to scope out the problem?  I would be more suspicious if it were some 
>> rig
>> that was new to me, or some mic that was new or something.  But, it 
>> is not
>> new and until now I have always had excellent reports.  Like I said,
>> 

Re: [Elecraft] K3 Hum on Audio...

[Tim]

Hi,

Equipment with non-ferrous enclosures are vulnerable to picking up magnetic 
fields from linear power supplies.  I found this out with my TT Corsair II, 
and the solution was to put the power supply on the other side of the radio, 
away from the audio circuitry.
The steel cabinets of the other manufacturers have some advantages.
73

Tim
GM4LMH 

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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

As noted in a previous post, I disconnected EVERYTHING.  Nothing on the back 
panel of the K3 at all except for a Li-nano-phosphate battery as my power 
source.  All AC off at the breaker panel for this room.  The only electrical 
equipment on was my K3 via the battery and my Macbook Pro laptop via its 
battery.

Given those conditions, the hum was still there.

Jim Brown suggested that I consider TXEQ to cut off the low frequencies,  I did 
max cut for all frequencies up to 400 Hz.  The hum did not start being 
attenuated until 400 Hz cut.  But, max cut on 400 Hz did not attenuate it 
completely.  I did not do higher frequencies.

So, anyone who might help -- where does this hum or buzz come from if nothing 
is connected to the K3 and there is no AC flowing anywhere in the room.  It is 
28 degrees outside, which is freezing cold plus for the northwest and I am not 
used to that but my next step is to go outside and check my grounding to ground 
points.

phil



On Jan 13, 2012, at 10:03 AM, Geoffrey Mackenzie-Kennedy wrote:

> When the KPA500 is in standby, I assume that its AC mains is still connected. 
>  Have you tried pulling the KPA500's mains plug to narrow
> the search?
> 
> Is your P3 sitting between the KPA500 and the K3?
> 
> 73,
> Geoff
> LX2AO
> 
> On January 13, 2012, at 18:20 +0100, "Phil Hystad"  wrote:
> 
> 
> 
>> If I lay my hand on the top of the K3 the hum disappears.  If I lay my hand 
>> on the P3 sitting next to K3 the hum disappears but not as much. And, I can 
>> do the same with other grounded equipment.  I have checked my grounds and 
>> they all seem to be pretty good.
> 
> and earlier
> 
>>> So, I am thinking maybe it has
>>> something to do with the KPA500.  So, I put that in Standby and the hum is
>>> still there on the audio.  The mic is the MH2 hand mic plugged into the
>>> front of the K3.
> 

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Re: [Elecraft] K3 Hum on Audio...

[Guy Olinger K2AV]

I've been ignoring this thread, but your last post piqued my interest.

Several questions require answers before I can go on.  Just note that while
we tend to concentrate on the last new thing, the "workbench" and
instruments and their connections have far too often been the entire
problem.  You would CERTAINLY NOT be the first, nor the last, to suffer
from this as some issues are ghastly subtle.

1) What frequency is the hum.
2) By what means are you detecting the hum?  Speaker?  Line out to spectral
audio program or some such on the Macbook?  Other means?  Other means,
describe the method and connections in boring detail. It is critically
important to precisely understand the means of measurement.
3) If detecting the hum on the Macbook, what level is the hum?
4) If detecting the hum on the Macbook, describe the connection between the
K3 and the Macbook in boring detail.

73, Guy.

On Fri, Jan 13, 2012 at 1:30 PM, Phil Hystad  wrote:

> As noted in a previous post, I disconnected EVERYTHING.  Nothing on the
> back panel of the K3 at all except for a Li-nano-phosphate battery as my
> power source.  All AC off at the breaker panel for this room.  The only
> electrical equipment on was my K3 via the battery and my Macbook Pro laptop
> via its battery.
>
> Given those conditions, the hum was still there.
>
> Jim Brown suggested that I consider TXEQ to cut off the low frequencies,
>  I did max cut for all frequencies up to 400 Hz.  The hum did not start
> being attenuated until 400 Hz cut.  But, max cut on 400 Hz did not
> attenuate it completely.  I did not do higher frequencies.
>
> So, anyone who might help -- where does this hum or buzz come from if
> nothing is connected to the K3 and there is no AC flowing anywhere in the
> room.  It is 28 degrees outside, which is freezing cold plus for the
> northwest and I am not used to that but my next step is to go outside and
> check my grounding to ground points.
>
> phil
>
>
>
> On Jan 13, 2012, at 10:03 AM, Geoffrey Mackenzie-Kennedy wrote:
>
> > When the KPA500 is in standby, I assume that its AC mains is still
> connected.  Have you tried pulling the KPA500's mains plug to narrow
> > the search?
> >
> > Is your P3 sitting between the KPA500 and the K3?
> >
> > 73,
> > Geoff
> > LX2AO
> >
> > On January 13, 2012, at 18:20 +0100, "Phil Hystad" 
> wrote:
> >
> > 
> >
> >> If I lay my hand on the top of the K3 the hum disappears.  If I lay my
> hand on the P3 sitting next to K3 the hum disappears but not as much. And,
> I can do the same with other grounded equipment.  I have checked my grounds
> and they all seem to be pretty good.
> >
> > and earlier
> >
> >>> So, I am thinking maybe it has
> >>> something to do with the KPA500.  So, I put that in Standby and the
> hum is
> >>> still there on the audio.  The mic is the MH2 hand mic plugged into the
> >>> front of the K3.
> >
>
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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

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


On Jan 13, 2012, at 10:15 AM, Ron D'Eau Claire wrote:

> Yeah, Phil, two mics doing it eliminates the easy idea of a bad wire in one
> of them. 
> 
> When switching mics, be sure to physically disconnect the one you are not
> using. An ungrounded mic hot lead might introduce hum, even if you have the
> other mic enabled.  
> 
> Hand effects suggest a ground loop- either AC or RF. Being in TEST mode
> eliminates RF, since you aren't making any. 
> 
> I'd start disconnecting things one at a time. If the hum is still there with
> everything but the mic and power supply connected, you can be sure it's not
> in the external gear. 
> 
> Do you have another power supply you can substitute? All it needs to do is
> provide enough current for receive, since you are "transmitting" in TEST
> mode. One possibility is that you'd lost filtering in the power supply. That
> can produce different levels of hum from different mics, depending upon the
> gain settings, etc. 
> 
> If it's clean on the alternate power supply, that leaves ONLY the K3, of
> course.
> 
> 73,  
> 
> Ron AC7AC
> 
> -Original Message-
> From: Phil Hystad [mailto:phys...@mac.com] 
> Sent: Friday, January 13, 2012 9:21 AM
> To: Ron D'Eau Claire
> Cc: 'Elecraft List'
> Subject: Re: [Elecraft] K3 Hum on Audio...
> 
> Ron,
> 
> I have been able to do more tests.  Unfortunately, it is in both mics but
> not as strong in the Yamaha CM500 mic as in the MH2 but it is present.
> 
> This morning I double checked all connections (most in the back).  This
> includes the key out to the KPA500, the plugs for the cm500, the external
> speaker, my foot PTT switch, and even the svga cable to the KPA500.  Nuts,
> have not tested the serial port yet.  However, absolutely no difference in
> behavior.   I can hear the hum on the speaker when I have the monitor gain
> cranked up a little bit and keying the mic in Test mode.
> 
> If I lay my hand on the top of the K3 the hum disappears.  If I lay my hand
> on the P3 sitting next to K3 the hum disappears but not as much.  And, I can
> do the same with other grounded equipment.  I have checked my grounds and
> they all seem to be pretty good.
> 
> So, I am at a loss as to what to try next.  This seemed to start on its own
> Wednesday afternoon after my last SSB QSO.  I say that because after that
> QSO, I turned the rigs off and then the next day (T

Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

Guy, 

Thanks for not ignoring my problem any more and lending a hand :-)

Answers to your 1) 2) 3) 4) questions below...
On Jan 13, 2012, at 11:09 AM, Guy Olinger K2AV wrote:

> I've been ignoring this thread, but your last post piqued my interest.  
> 
> Several questions require answers before I can go on.  Just note that while 
> we tend to concentrate on the last new thing, the "workbench" and instruments 
> and their connections have far too often been the entire problem.  You would 
> CERTAINLY NOT be the first, nor the last, to suffer from this as some issues 
> are ghastly subtle.  
> 
> 1) What frequency is the hum.

Well, I am not good at guessing the frequency but it does sound like AC power 
type hum, maybe a little higher but I am just guessing.

> 2) By what means are you detecting the hum?  Speaker?  Line out to spectral 
> audio program or some such on the Macbook?  Other means?  Other means, 
> describe the method and connections in boring detail. It is critically 
> important to precisely understand the means of measurement.  

Hum is detected in all (I repeat ALL) audio outputs.   These include my West 
Mountain COMspkr, and it includes the internal K3 speaker when the COMspkr is 
unplugged, and it includes my Yamaha CM500 headphones.

It does not include my Macbook though -- I do not use my computers with the 
computer in any fashion (no DATA, no Audio, no speaker use, no application 
programs except for the K3, P3, and KPA500 utility programs).


> 3) If detecting the hum on the Macbook, what level is the hum?

Not detected on Macbook -- Macbook is 8 feet away and not connected to rigs in 
any way.


> 4) If detecting the hum on the Macbook, describe the connection between the 
> K3 and the Macbook in boring detail.  


See above.



> 
> 73, Guy.
> 
> On Fri, Jan 13, 2012 at 1:30 PM, Phil Hystad  wrote:
> As noted in a previous post, I disconnected EVERYTHING.  Nothing on the back 
> panel of the K3 at all except for a Li-nano-phosphate battery as my power 
> source.  All AC off at the breaker panel for this room.  The only electrical 
> equipment on was my K3 via the battery and my Macbook Pro laptop via its 
> battery.
> 
> Given those conditions, the hum was still there.
> 
> Jim Brown suggested that I consider TXEQ to cut off the low frequencies,  I 
> did max cut for all frequencies up to 400 Hz.  The hum did not start being 
> attenuated until 400 Hz cut.  But, max cut on 400 Hz did not attenuate it 
> completely.  I did not do higher frequencies.
> 
> So, anyone who might help -- where does this hum or buzz come from if nothing 
> is connected to the K3 and there is no AC flowing anywhere in the room.  It 
> is 28 degrees outside, which is freezing cold plus for the northwest and I am 
> not used to that but my next step is to go outside and check my grounding to 
> ground points.
> 
> phil
> 
> 
> 
> On Jan 13, 2012, at 10:03 AM, Geoffrey Mackenzie-Kennedy wrote:
> 
> > When the KPA500 is in standby, I assume that its AC mains is still 
> > connected.  Have you tried pulling the KPA500's mains plug to narrow
> > the search?
> >
> > Is your P3 sitting between the KPA500 and the K3?
> >
> > 73,
> > Geoff
> > LX2AO
> >
> > On January 13, 2012, at 18:20 +0100, "Phil Hystad"  wrote:
> >
> > 
> >
> >> If I lay my hand on the top of the K3 the hum disappears.  If I lay my 
> >> hand on the P3 sitting next to K3 the hum disappears but not as much. And, 
> >> I can do the same with other grounded equipment.  I have checked my 
> >> grounds and they all seem to be pretty good.
> >
> > and earlier
> >
> >>> So, I am thinking maybe it has
> >>> something to do with the KPA500.  So, I put that in Standby and the hum is
> >>> still there on the audio.  The mic is the MH2 hand mic plugged into the
> >>> front of the K3.
> >
> 
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Re: [Elecraft] K3 Hum on Audio...

[Ron D'Eau Claire]

Wow - this is strange! 

1) Are all the K3's enclosure screws tight? Have you tried tapping or
lifting the K3 while listening to the hum (looking for an intermittent
connection)? 

2) Does the hum remain if you key the rig in CW mode?

2) If you move the K3 and battery supply to a different location (room
perhaps) does the hum remain?

Your needing to cut up to 400 Hz is not surprising. It's not unusual for 60
Hz hum to have a number of harmonics if the waveform is getting distorted in
the process of being picked up.

The fact that it's being picked up with AC disconnected to everything in the
room suggests that it's a fairly high-level high-impedance circuit picking
it up. Such circuits can pick up 60/120 Hz buzz from many blocks or miles
around. 

BTW, I can't imagine how an external ground would have an effect with
nothing connected to the K3, but if you're thinking of checking outside,
now's the time. I see we're due for snow at low elevations in the Northwest
by tomorrow night. 

Ron AC7AC

-Original Message-

As noted in a previous post, I disconnected EVERYTHING.  Nothing on the back
panel of the K3 at all except for a Li-nano-phosphate battery as my power
source.  All AC off at the breaker panel for this room.  The only electrical
equipment on was my K3 via the battery and my Macbook Pro laptop via its
battery.

Given those conditions, the hum was still there.

Jim Brown suggested that I consider TXEQ to cut off the low frequencies,  I
did max cut for all frequencies up to 400 Hz.  The hum did not start being
attenuated until 400 Hz cut.  But, max cut on 400 Hz did not attenuate it
completely.  I did not do higher frequencies.

So, anyone who might help -- where does this hum or buzz come from if
nothing is connected to the K3 and there is no AC flowing anywhere in the
room.  It is 28 degrees outside, which is freezing cold plus for the
northwest and I am not used to that but my next step is to go outside and
check my grounding to ground points.

phil


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Re: [Elecraft] K3 Hum on Audio...

[Ron D'Eau Claire]

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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Re: [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
> 

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Re: [Elecraft] K3 Hum on Audio...

[Buck - k4ia]

Is it possible that in setting the power level, you accidentally turned 
up the compression?  (they are on the same knob).  If the compression is 
too high it will make a rushing, buzzing sound on the audio

Buck
k4ia


On 1/13/2012 2:09 PM, Phil Hystad wrote:
> 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
>
>
> On Jan 13, 2012, at 10:15 AM, Ron D'Eau Claire wrote:
>
>> Yeah, Phil, two mics doing it eliminates the easy idea of a bad wire in one
>> of them.
>>
>> When switching mics, be sure to physically disconnect the one you are not
>> using. An ungrounded mic hot lead might introduce hum, even if you have the
>> other mic enabled.
>>
>> Hand effects suggest a ground loop- either AC or RF. Being in TEST mode
>> eliminates RF, since you aren't making any.
>>
>> I'd start disconnecting things one at a time. If the hum is still there with
>> everything but the mic and power supply connected, you can be sure it's not
>> in the external gear.
>>
>> Do you have another power supply you can substitute? All it needs to do is
>> provide enough current for receive, since you are "transmitting" in TEST
>> mode. One possibility is that you'd lost filtering in the power supply. That
>> can produce different levels of hum from different mics, depending upon the
>> gain settings, etc.
>>
>> If it's clean on the alternate power supply, that leaves ONLY the K3, of
>> course.
>>
>> 73,
>>
>> Ron AC7AC
>>
>> -Original Message-
>> From: Phil Hystad [mailto:phys...@mac.com]
>> Sent: Friday, January 13, 2012 9:21 AM
>> To: Ron D'Eau Claire
>> Cc: 'Elecraft List'
>> Subject: Re: [Elecraft] K3 Hum on Audio...
>>
>> Ron,
>>
>> I have been able to do more tests.  Unfortunately, it is in both mics but
>> not as strong in the Yamaha CM500 mic as in the MH2 but it is present.
>>
>> This morning I double checked all connections (most in the back).  This
>> includes the key out to the KPA500, the plugs for the cm500, the external
>> speaker, my foot PTT switch, and even the svga cable to the KPA500.  Nuts,
>> have not tested the serial port yet.  However, absolutely no difference in
>>

Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

Buck,

Good suggestion but that was one of the things that I checked earlier this 
morning when I had the hum on the mic.  Both compression level and mic gain 
were the same that they always have been.

73, phil, K7PEH


On Jan 13, 2012, at 12:02 PM, Buck - k4ia wrote:

> Is it possible that in setting the power level, you accidentally turned 
> up the compression?  (they are on the same knob).  If the compression is 
> too high it will make a rushing, buzzing sound on the audio
> 
> Buck
> k4ia
> 
> 
> On 1/13/2012 2:09 PM, Phil Hystad wrote:
>> 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
>> 
>> 
>> On Jan 13, 2012, at 10:15 AM, Ron D'Eau Claire wrote:
>> 
>>> Yeah, Phil, two mics doing it eliminates the easy idea of a bad wire in one
>>> of them.
>>> 
>>> When switching mics, be sure to physically disconnect the one you are not
>>> using. An ungrounded mic hot lead might introduce hum, even if you have the
>>> other mic enabled.
>>> 
>>> Hand effects suggest a ground loop- either AC or RF. Being in TEST mode
>>> eliminates RF, since you aren't making any.
>>> 
>>> I'd start disconnecting things one at a time. If the hum is still there with
>>> everything but the mic and power supply connected, you can be sure it's not
>>> in the external gear.
>>> 
>>> Do you have another power supply you can substitute? All it needs to do is
>>> provide enough current for receive, since you are "transmitting" in TEST
>>> mode. One possibility is that you'd lost filtering in the power supply. That
>>> can produce different levels of hum from different mics, depending upon the
>>> gain settings, etc.
>>> 
>>> If it's clean on the alternate power supply, that leaves ONLY the K3, of
>>> course.
>>> 
>>> 73,
>>> 
>>> Ron AC7AC
>>> 
>>> -Original Message-
>>> From: Phil Hystad [mailto:phys...@mac.com]
>>> Sent: Friday, January 13, 2012 9:21 AM
>>> To: 

Re: [Elecraft] K3 Hum on Audio...

[riese-k3djc]

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  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
> > 
> 
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

bob,

I am not sure if you understand my previous problems I was reporting.  The hum 
has nothing to do with the mic plugged into the K3 or not (obvious if the mic 
is not plugged in, there is no problems).  But, the hum comes with PTT transmit 
and not merely because the mic is plugged in.  

But, for some unusual reason, the hum is no longer there.  But I fear it is 
waiting out there, maybe in the greenbelt behind our house, to make a sneak 
attack when I least expect it.

73, phil


On Jan 13, 2012, at 12:09 PM, riese-k3...@juno.com wrote:

> 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  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
>>> 
>> 
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq

Re: [Elecraft] K3 Hum on Audio...

[NZ0T]

Phil, which firmware version are you using?  I was using the beta 4.47 and
I developed audio problems the other night,  After I deleted 4.47 and went
back to the latest production firmware all was fine.  Sorry if this has
already been discussed - I just read this thread.

73 Bill NZ0T

On Fri, Jan 13, 2012 at 1:32 PM, Phil Hystad-3 [via Elecraft] <
ml-node+s365791n7185299...@n2.nabble.com> wrote:

> 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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> email]
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>  If you reply to this email, your message will be added to the discussion
> below:
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> h

Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

No one mentioned the firmware level but I am not on any beta version.  I am at 
MCU firmware level 4.39.

73, phil, K7PEH

On Jan 13, 2012, at 12:33 PM, NZ0T wrote:

> Phil, which firmware version are you using?  I was using the beta 4.47 and
> I developed audio problems the other night,  After I deleted 4.47 and went
> back to the latest production firmware all was fine.  Sorry if this has
> already been discussed - I just read this thread.
> 
> 73 Bill NZ0T
> 
> On Fri, Jan 13, 2012 at 1:32 PM, Phil Hystad-3 [via Elecraft] <
> ml-node+s365791n7185299...@n2.nabble.com> wrote:
> 
>> 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
>>> 
>> 
>> __
>> 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
>> 
>> 
>> --
>> If you reply to this em

Re: [Elecraft] K3 Hum on Audio...

[riese-k3djc]

On Fri, 13 Jan 2012 12:26:47 -0800 Phil Hystad  writes:
> bob,
> 
> I am not sure if you understand my previous problems I was 
> reporting.  The hum has nothing to do with the mic plugged into the 
> K3 or not (obvious if the mic is not plugged in, there is no 
> problems).  But, the hum comes with PTT transmit and not merely 
> because the mic is plugged in.  
> 
> But, for some unusual reason, the hum is no longer there.  But I 
> fear it is waiting out there, maybe in the greenbelt behind our 
> house, to make a sneak attack when I least expect it.
> 

Those evil north Koreans
Har

GL on your fixing the problem,,, been there done that

Bob K3DJC





73, phil
> 
> 
> On Jan 13, 2012, at 12:09 PM, riese-k3...@juno.com wrote:
> 
> > 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  
> 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 aro

Re: [Elecraft] K3 Hum on Audio...

[Jim Brown]

On 1/13/2012 10:30 AM, Phil Hystad wrote:
> I disconnected EVERYTHING.  Nothing on the back panel of the K3 at all except 
> for a Li-nano-phosphate battery as my power source.

Was your antenna connected?  If so, where is the coax shield connected 
to ANYTHING -- the earth, other gear, at a tower, etc.?  These are all 
paths for AC leakage current, and your K3 can be in that path.

>All AC off at the breaker panel for this room.  The only electrical 
> equipment on was my K3 via the battery and my Macbook Pro laptop via its 
> battery.
>
> Given those conditions, the hum was still there.
>
> Jim Brown suggested that I consider TXEQ to cut off the low frequencies,  I 
> did max cut for all frequencies up to 400 Hz.  The hum did not start being 
> attenuated until 400 Hz cut.  But, max cut on 400 Hz did not attenuate it 
> completely.  I did not do higher frequencies.

Then what you have is BUZZ, NOT HUM. HUM would be affected ONLY by the 
60 Hz  frequency band.  The coupling mechanisms are entirely different. 
That's why it was my first question!

BUZZ is leakage current from the AC mains power, OR, as Ron suggested, a 
flaky shield connection of the mic.  BUZZ is almost never due to 
magnetic coupling, so magnetic shielding doesn't matter.  What DOES 
matter is ELECTRIC shielding, which is what the cable shield provides.  
And MAIN thing that matters is BONDING -- CHASSIS TO CHASSIS, and from 
the combination of those chassis to the station ground, AND to the power 
system ground.

Study   http://audiosystemsgroup.com/HamInterfacing.pdf

73, Jim Brown  K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

Jim,

In answer to your first question below, that particular test NOTHING was 
connected other then the battery to provide power.  That included the antenna.

I will read your paper -- maybe it will describe hum and buzz as to how they 
sound different.  If you know of a good audio stream available on the web maybe 
I can listen to that.  But, audio is definitely not a strong suit for me and 
this is the first time I have heard of a distinction in buzz and hum.  I don't 
mean that I haven't heard of different kinds of hum or buzz, just that I didn't 
know that the terms had been so precisely defined.

However, the good news is that the problem no longer occurs (as I had mentioned 
in a previous post).  Not sure of the cause though but I am heavily leaning 
towards some kind of loose connection or other electro-mechanical problem with 
the mic itself (or its connector to the K3).  That seems to be the only source 
so far that can meet the requirements of all the tests that I did.

73, phil


On Jan 13, 2012, at 2:11 PM, Jim Brown wrote:

> On 1/13/2012 10:30 AM, Phil Hystad wrote:
>> I disconnected EVERYTHING.  Nothing on the back panel of the K3 at all 
>> except for a Li-nano-phosphate battery as my power source.
> 
> Was your antenna connected?  If so, where is the coax shield connected 
> to ANYTHING -- the earth, other gear, at a tower, etc.?  These are all 
> paths for AC leakage current, and your K3 can be in that path.
> 
>>   All AC off at the breaker panel for this room.  The only electrical 
>> equipment on was my K3 via the battery and my Macbook Pro laptop via its 
>> battery.
>> 
>> Given those conditions, the hum was still there.
>> 
>> Jim Brown suggested that I consider TXEQ to cut off the low frequencies,  I 
>> did max cut for all frequencies up to 400 Hz.  The hum did not start being 
>> attenuated until 400 Hz cut.  But, max cut on 400 Hz did not attenuate it 
>> completely.  I did not do higher frequencies.
> 
> Then what you have is BUZZ, NOT HUM. HUM would be affected ONLY by the 
> 60 Hz  frequency band.  The coupling mechanisms are entirely different. 
> That's why it was my first question!
> 
> BUZZ is leakage current from the AC mains power, OR, as Ron suggested, a 
> flaky shield connection of the mic.  BUZZ is almost never due to 
> magnetic coupling, so magnetic shielding doesn't matter.  What DOES 
> matter is ELECTRIC shielding, which is what the cable shield provides.  
> And MAIN thing that matters is BONDING -- CHASSIS TO CHASSIS, and from 
> the combination of those chassis to the station ground, AND to the power 
> system ground.
> 
> Study   http://audiosystemsgroup.com/HamInterfacing.pdf
> 
> 73, Jim Brown  K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Guy Olinger K2AV]

Let's call it buzz.  If it was AC power hum the main components would be
60, 120 and 180 Hz.  Cutting 400 Hz and below would have made it
significantly better.  When the K3 is running on batteries without ANY
mikes and other connections, it has NO way to produce 60/120/180 Hz related
to AC house voltage. (I am PRESUMING that your batteries did not have a
charger running on them, or long leads. Anything connected to the charger
is connected to the K3.)  It DOES have misc low level processing artifacts
that are normally so far down as to be covered up by the normal noise
levels of anything coming in on audio inputs at routine levels.

That said, what you have sounds more like gain gone to maximum looking for
input when power level has never been defined, or has had all prior data
wiped.  Especially if compression is set to max, you will now have many
dB's of amplification in force as the rig attempts to provide 100 watts of
output with no power level or mic gain defined.

Once you set yourself to something less than wide open on all bands and
modes and inputs, and your compression to a realistic level that matches
your voice and microphones, it will no longer be running "open gain" and
amplifying internal circuit noise (always present in ANY electronic gear)
to audible levels.

73, Guy.

On Fri, Jan 13, 2012 at 5:11 PM, Jim Brown wrote:

> On 1/13/2012 10:30 AM, Phil Hystad wrote:
> > I disconnected EVERYTHING.  Nothing on the back panel of the K3 at all
> except for a Li-nano-phosphate battery as my power source.
>
> Was your antenna connected?  If so, where is the coax shield connected
> to ANYTHING -- the earth, other gear, at a tower, etc.?  These are all
> paths for AC leakage current, and your K3 can be in that path.
>
> >All AC off at the breaker panel for this room.  The only electrical
> equipment on was my K3 via the battery and my Macbook Pro laptop via its
> battery.
> >
> > Given those conditions, the hum was still there.
> >
> > Jim Brown suggested that I consider TXEQ to cut off the low frequencies,
>  I did max cut for all frequencies up to 400 Hz.  The hum did not start
> being attenuated until 400 Hz cut.  But, max cut on 400 Hz did not
> attenuate it completely.  I did not do higher frequencies.
>
> Then what you have is BUZZ, NOT HUM. HUM would be affected ONLY by the
> 60 Hz  frequency band.  The coupling mechanisms are entirely different.
> That's why it was my first question!
>
> BUZZ is leakage current from the AC mains power, OR, as Ron suggested, a
> flaky shield connection of the mic.  BUZZ is almost never due to
> magnetic coupling, so magnetic shielding doesn't matter.  What DOES
> matter is ELECTRIC shielding, which is what the cable shield provides.
> And MAIN thing that matters is BONDING -- CHASSIS TO CHASSIS, and from
> the combination of those chassis to the station ground, AND to the power
> system ground.
>
> Study   http://audiosystemsgroup.com/HamInterfacing.pdf
>
> 73, Jim Brown  K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

Guy,

Thanks for the comments.  Later on I might experiment to see if I can purposely 
reproduce the buzz by methods you mention.

Yes, my test condition was using ABSOLUTELY no AC and no nearby AC or AC 
artifacts.  No charger on the battery but then again I had AC switched off at 
the breaker panel during those tests.  The leads on the batter were about 4 
inches long.  The battery by the way was a 4S1P configuration (4 individual 
cells) producing 1.38 volts of A123 Systems Lithium Nano-Phosphate battery 
available for lots of money from Buddipole.  I like them so much, I am planning 
on buying more.

phil


On Jan 13, 2012, at 2:34 PM, Guy Olinger K2AV wrote:

> Let's call it buzz.  If it was AC power hum the main components would be
> 60, 120 and 180 Hz.  Cutting 400 Hz and below would have made it
> significantly better.  When the K3 is running on batteries without ANY
> mikes and other connections, it has NO way to produce 60/120/180 Hz related
> to AC house voltage. (I am PRESUMING that your batteries did not have a
> charger running on them, or long leads. Anything connected to the charger
> is connected to the K3.)  It DOES have misc low level processing artifacts
> that are normally so far down as to be covered up by the normal noise
> levels of anything coming in on audio inputs at routine levels.
> 
> That said, what you have sounds more like gain gone to maximum looking for
> input when power level has never been defined, or has had all prior data
> wiped.  Especially if compression is set to max, you will now have many
> dB's of amplification in force as the rig attempts to provide 100 watts of
> output with no power level or mic gain defined.
> 
> Once you set yourself to something less than wide open on all bands and
> modes and inputs, and your compression to a realistic level that matches
> your voice and microphones, it will no longer be running "open gain" and
> amplifying internal circuit noise (always present in ANY electronic gear)
> to audible levels.
> 
> 73, Guy.
> 
> On Fri, Jan 13, 2012 at 5:11 PM, Jim Brown wrote:
> 
>> On 1/13/2012 10:30 AM, Phil Hystad wrote:
>>> I disconnected EVERYTHING.  Nothing on the back panel of the K3 at all
>> except for a Li-nano-phosphate battery as my power source.
>> 
>> Was your antenna connected?  If so, where is the coax shield connected
>> to ANYTHING -- the earth, other gear, at a tower, etc.?  These are all
>> paths for AC leakage current, and your K3 can be in that path.
>> 
>>>   All AC off at the breaker panel for this room.  The only electrical
>> equipment on was my K3 via the battery and my Macbook Pro laptop via its
>> battery.
>>> 
>>> Given those conditions, the hum was still there.
>>> 
>>> Jim Brown suggested that I consider TXEQ to cut off the low frequencies,
>> I did max cut for all frequencies up to 400 Hz.  The hum did not start
>> being attenuated until 400 Hz cut.  But, max cut on 400 Hz did not
>> attenuate it completely.  I did not do higher frequencies.
>> 
>> Then what you have is BUZZ, NOT HUM. HUM would be affected ONLY by the
>> 60 Hz  frequency band.  The coupling mechanisms are entirely different.
>> That's why it was my first question!
>> 
>> BUZZ is leakage current from the AC mains power, OR, as Ron suggested, a
>> flaky shield connection of the mic.  BUZZ is almost never due to
>> magnetic coupling, so magnetic shielding doesn't matter.  What DOES
>> matter is ELECTRIC shielding, which is what the cable shield provides.
>> And MAIN thing that matters is BONDING -- CHASSIS TO CHASSIS, and from
>> the combination of those chassis to the station ground, AND to the power
>> system ground.
>> 
>> Study   http://audiosystemsgroup.com/HamInterfacing.pdf
>> 
>> 73, Jim Brown  K9YC
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
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>> 
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Re: [Elecraft] K3 Hum on Audio...

[Phil Hystad]

Please multiply the voltage by 10 in the sentence below where I am describing 
the battery.  I think I rushed to quickly to drop in that decimal point.

And, thanks for all the help and comments from others.  I always learn a lot in 
these trials.

phil


On Jan 13, 2012, at 2:41 PM, Phil Hystad wrote:

> Guy,
> 
> Thanks for the comments.  Later on I might experiment to see if I can 
> purposely reproduce the buzz by methods you mention.
> 
> Yes, my test condition was using ABSOLUTELY no AC and no nearby AC or AC 
> artifacts.  No charger on the battery but then again I had AC switched off at 
> the breaker panel during those tests.  The leads on the batter were about 4 
> inches long.  The battery by the way was a 4S1P configuration (4 individual 
> cells) producing 1.38 volts of A123 Systems Lithium Nano-Phosphate battery 
> available for lots of money from Buddipole.  I like them so much, I am 
> planning on buying more.
> 
> phil
> 
> 
> On Jan 13, 2012, at 2:34 PM, Guy Olinger K2AV wrote:
> 
>> Let's call it buzz.  If it was AC power hum the main components would be
>> 60, 120 and 180 Hz.  Cutting 400 Hz and below would have made it
>> significantly better.  When the K3 is running on batteries without ANY
>> mikes and other connections, it has NO way to produce 60/120/180 Hz related
>> to AC house voltage. (I am PRESUMING that your batteries did not have a
>> charger running on them, or long leads. Anything connected to the charger
>> is connected to the K3.)  It DOES have misc low level processing artifacts
>> that are normally so far down as to be covered up by the normal noise
>> levels of anything coming in on audio inputs at routine levels.
>> 
>> That said, what you have sounds more like gain gone to maximum looking for
>> input when power level has never been defined, or has had all prior data
>> wiped.  Especially if compression is set to max, you will now have many
>> dB's of amplification in force as the rig attempts to provide 100 watts of
>> output with no power level or mic gain defined.
>> 
>> Once you set yourself to something less than wide open on all bands and
>> modes and inputs, and your compression to a realistic level that matches
>> your voice and microphones, it will no longer be running "open gain" and
>> amplifying internal circuit noise (always present in ANY electronic gear)
>> to audible levels.
>> 
>> 73, Guy.
>> 
>> On Fri, Jan 13, 2012 at 5:11 PM, Jim Brown wrote:
>> 
>>> On 1/13/2012 10:30 AM, Phil Hystad wrote:
 I disconnected EVERYTHING.  Nothing on the back panel of the K3 at all
>>> except for a Li-nano-phosphate battery as my power source.
>>> 
>>> Was your antenna connected?  If so, where is the coax shield connected
>>> to ANYTHING -- the earth, other gear, at a tower, etc.?  These are all
>>> paths for AC leakage current, and your K3 can be in that path.
>>> 
  All AC off at the breaker panel for this room.  The only electrical
>>> equipment on was my K3 via the battery and my Macbook Pro laptop via its
>>> battery.
 
 Given those conditions, the hum was still there.
 
 Jim Brown suggested that I consider TXEQ to cut off the low frequencies,
>>> I did max cut for all frequencies up to 400 Hz.  The hum did not start
>>> being attenuated until 400 Hz cut.  But, max cut on 400 Hz did not
>>> attenuate it completely.  I did not do higher frequencies.
>>> 
>>> Then what you have is BUZZ, NOT HUM. HUM would be affected ONLY by the
>>> 60 Hz  frequency band.  The coupling mechanisms are entirely different.
>>> That's why it was my first question!
>>> 
>>> BUZZ is leakage current from the AC mains power, OR, as Ron suggested, a
>>> flaky shield connection of the mic.  BUZZ is almost never due to
>>> magnetic coupling, so magnetic shielding doesn't matter.  What DOES
>>> matter is ELECTRIC shielding, which is what the cable shield provides.
>>> And MAIN thing that matters is BONDING -- CHASSIS TO CHASSIS, and from
>>> the combination of those chassis to the station ground, AND to the power
>>> system ground.
>>> 
>>> Study   http://audiosystemsgroup.com/HamInterfacing.pdf
>>> 
>>> 73, Jim Brown  K9YC
>>> __
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>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft@mailman.qth.net
>>> 
>>> This list hosted by: http://www.qsl.net
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>>> 
>> __
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Re: [Elecraft] K3 Hum on Audio...

[N2TK, Tony]

Make sure the LIN IN is not turned up. Early on I had a problem with hum in
my audio, especially if an amp was close to the K3. For some reason my LIN
IN was at max. Turned it down and hum went away.
73,
N2TK, Tony

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Phil Hystad
Sent: Friday, January 13, 2012 12:54 PM
To: j...@audiosystemsgroup.com
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 Hum on Audio...

Jim,

Well, I would call it mostly a buzz.  Also, the only near magnetic field of
the KPA500 power transformer is off, I mean powered off and unplugged, so
that does not seem to be the problem.

I just ran another test with everything disconnected, including ground and
coax.  With the K3 in TEST mode, key-down on the mic still produces the hum.
I double checked the grounds.  I did this because if I were to touch
anything metal on the k3, the metal part of the PL259 or the ground strap,
the hum is damped quite a bit to almost insignificant.  It seems that if my
rig were already well grounded this would not happen so I am curious if this
is something I would normally expect.

I will experiment with the TXEQ but this is a real puzzle I would like to
solve, not merely erase it.  

73, phil


On Jan 13, 2012, at 9:37 AM, Jim Brown wrote:

> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500
mic as in the MH2 but it is present.
> 
> Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly 
> harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field 
> coupling into the audio, either from a big power transformer (like the 
> one in a power amp or a big linear power supply) or from a AC power 
> wiring fault called a double-bonded neutral.
> 
> The K3 has unshielded audio transformers at all the audio inputs and 
> outputs, and an unshielded transformer is a sitting duck for magnetic 
> fields.
> 
> The good news is that the K3 has excellent audio equalization (TXEQ) 
> that allows us to remove that 60 Hz hum by filtering.  The lower audio 
> frequencies in the human voice make NO useful contribution to speech 
> intelligibility, but they do waste transmit power. So it is ALWAYS a 
> good thing to set the TXEQ for maximum cut of the lowest two bands, 
> and at least some cut of the third band. This is true with virtually 
> ALL mics and ALL voices.  AND it will reduce that hum enough that you 
> may no longer hear it.
> 
> There are several solutions to magnetic field coupling.  1) Rotate the 
> noise source or the victim circuit to put the fields at right angles 
> to the victim.  2) Move the noise source further from the victim. 3) 
> If the hum field is produced by that AC power wiring error, fix the 
> error to eliminate the field.
> 
> 73, Jim K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Lew Phelps K6LMP]

Thank you, Tony!

I had developed a maddening audio hum suddenly, and couldn't find the cause.  
The curious thing was that it was WORSE when no mike was plugged into the jack 
on the back panel.

Based on your email, I checked the menu settings. Sure enough, MIC + LINE:  ON. 
 Switched to OFF and the hum totally disappeared. You don't need to adjust the 
LIN volume; just cut it off entirely.

Lew K6LMP


On Jan 14, 2012, at 9:02 AM, N2TK, Tony wrote:

> Make sure the LIN IN is not turned up. Early on I had a problem with hum in
> my audio, especially if an amp was close to the K3. For some reason my LIN
> IN was at max. Turned it down and hum went away.
> 73,
> N2TK, Tony
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net
> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Phil Hystad
> Sent: Friday, January 13, 2012 12:54 PM
> To: j...@audiosystemsgroup.com
> Cc: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] K3 Hum on Audio...
> 
> Jim,
> 
> Well, I would call it mostly a buzz.  Also, the only near magnetic field of
> the KPA500 power transformer is off, I mean powered off and unplugged, so
> that does not seem to be the problem.
> 
> I just ran another test with everything disconnected, including ground and
> coax.  With the K3 in TEST mode, key-down on the mic still produces the hum.
> I double checked the grounds.  I did this because if I were to touch
> anything metal on the k3, the metal part of the PL259 or the ground strap,
> the hum is damped quite a bit to almost insignificant.  It seems that if my
> rig were already well grounded this would not happen so I am curious if this
> is something I would normally expect.
> 
> I will experiment with the TXEQ but this is a real puzzle I would like to
> solve, not merely erase it.  
> 
> 73, phil
> 
> 
> On Jan 13, 2012, at 9:37 AM, Jim Brown wrote:
> 
>> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500
> mic as in the MH2 but it is present.
>> 
>> Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly 
>> harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field 
>> coupling into the audio, either from a big power transformer (like the 
>> one in a power amp or a big linear power supply) or from a AC power 
>> wiring fault called a double-bonded neutral.
>> 
>> The K3 has unshielded audio transformers at all the audio inputs and 
>> outputs, and an unshielded transformer is a sitting duck for magnetic 
>> fields.
>> 
>> The good news is that the K3 has excellent audio equalization (TXEQ) 
>> that allows us to remove that 60 Hz hum by filtering.  The lower audio 
>> frequencies in the human voice make NO useful contribution to speech 
>> intelligibility, but they do waste transmit power. So it is ALWAYS a 
>> good thing to set the TXEQ for maximum cut of the lowest two bands, 
>> and at least some cut of the third band. This is true with virtually 
>> ALL mics and ALL voices.  AND it will reduce that hum enough that you 
>> may no longer hear it.
>> 
>> There are several solutions to magnetic field coupling.  1) Rotate the 
>> noise source or the victim circuit to put the fields at right angles 
>> to the victim.  2) Move the noise source further from the victim. 3) 
>> If the hum field is produced by that AC power wiring error, fix the 
>> error to eliminate the field.
>> 
>> 73, Jim K9YC
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
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> 
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Re: [Elecraft] K3 Hum on Audio...

This is a "common" problem when a amplifer is placed next to the left side of 
the K3 (especially if the transformer in the amp is on the rigt side - like the 
Alpha amps).

The problem is caused because the K3 line in has a isolation transformer 
conveniently located on the left side.  Place a power transformer next to it, 
and all hell breaks loose (something to do with the magnetic lines of force 
interacting).

It took me a few hours of contemplating and experimenting to figure this out.  
If someone has come up with a easy "fix", please let me know.  I tried buying a 
steel plate (alum will definitely not work) at Home Depot and placed that 
between the K3 and amp; it did nothing to fix the problem (or even help).   One 
sure fire fix is to turn off the amp!

Dick K8ZTT




--- k6...@me.com wrote:

From: Lew Phelps K6LMP 
To: "Elecraft@mailman.qth.net List" 
Subject: Re: [Elecraft] K3 Hum on Audio...
Date: Thu, 02 Feb 2012 10:24:07 -0800

Thank you, Tony!

I had developed a maddening audio hum suddenly, and couldn't find the cause.  
The curious thing was that it was WORSE when no mike was plugged into the jack 
on the back panel.

Based on your email, I checked the menu settings. Sure enough, MIC + LINE:  ON. 
 Switched to OFF and the hum totally disappeared. You don't need to adjust the 
LIN volume; just cut it off entirely.

Lew K6LMP


On Jan 14, 2012, at 9:02 AM, N2TK, Tony wrote:

> Make sure the LIN IN is not turned up. Early on I had a problem with hum in
> my audio, especially if an amp was close to the K3. For some reason my LIN
> IN was at max. Turned it down and hum went away.
> 73,
> N2TK, Tony
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net
> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Phil Hystad
> Sent: Friday, January 13, 2012 12:54 PM
> To: j...@audiosystemsgroup.com
> Cc: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] K3 Hum on Audio...
> 
> Jim,
> 
> Well, I would call it mostly a buzz.  Also, the only near magnetic field of
> the KPA500 power transformer is off, I mean powered off and unplugged, so
> that does not seem to be the problem.
> 
> I just ran another test with everything disconnected, including ground and
> coax.  With the K3 in TEST mode, key-down on the mic still produces the hum.
> I double checked the grounds.  I did this because if I were to touch
> anything metal on the k3, the metal part of the PL259 or the ground strap,
> the hum is damped quite a bit to almost insignificant.  It seems that if my
> rig were already well grounded this would not happen so I am curious if this
> is something I would normally expect.
> 
> I will experiment with the TXEQ but this is a real puzzle I would like to
> solve, not merely erase it.  
> 
> 73, phil
> 
> 
> On Jan 13, 2012, at 9:37 AM, Jim Brown wrote:
> 
>> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500
> mic as in the MH2 but it is present.
>> 
>> Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly 
>> harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field 
>> coupling into the audio, either from a big power transformer (like the 
>> one in a power amp or a big linear power supply) or from a AC power 
>> wiring fault called a double-bonded neutral.
>> 
>> The K3 has unshielded audio transformers at all the audio inputs and 
>> outputs, and an unshielded transformer is a sitting duck for magnetic 
>> fields.
>> 
>> The good news is that the K3 has excellent audio equalization (TXEQ) 
>> that allows us to remove that 60 Hz hum by filtering.  The lower audio 
>> frequencies in the human voice make NO useful contribution to speech 
>> intelligibility, but they do waste transmit power. So it is ALWAYS a 
>> good thing to set the TXEQ for maximum cut of the lowest two bands, 
>> and at least some cut of the third band. This is true with virtually 
>> ALL mics and ALL voices.  AND it will reduce that hum enough that you 
>> may no longer hear it.
>> 
>> There are several solutions to magnetic field coupling.  1) Rotate the 
>> noise source or the victim circuit to put the fields at right angles 
>> to the victim.  2) Move the noise source further from the victim. 3) 
>> If the hum field is produced by that AC power wiring error, fix the 
>> error to eliminate the field.
>> 
>> 73, Jim K9YC
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
>> 
>&g

Re: [Elecraft] K3 Hum on Audio...

[Guy Olinger K2AV]

This is an endemic "uncurable" problem.  By uncurable, I mean there is
no reasonable way to shield or "cure" it.  There is nothing WRONG with
either the amp or the K3.  It has the same issues as an over/under
refrigerator-stove combination.  They just don't belong together, and
a carefully laid out kitchen design would never have things arranged
that way.

Redo your station layout.  And while you're redesigning, figure out
how to NOT run your RF connections past your computer, or your RF
connections anywhere in parallel with the computer connections to any
of your radio gear.

We used to have this problem with amps next to CRT monitors causing a
very irritating constant wiggle in the display.  LED flat monitors
fixed that.  But isolation transformers and amplifier primary power
transformers are going to be with us for the long haul.,

Good luck and 73, Guy.

On Fri, Feb 3, 2012 at 3:21 PM,   wrote:
> This is a "common" problem when a amplifer is placed next to the left side of 
> the K3 (especially if the transformer in the amp is on the rigt side - like 
> the Alpha amps).
>
> The problem is caused because the K3 line in has a isolation transformer 
> conveniently located on the left side.  Place a power transformer next to it, 
> and all hell breaks loose (something to do with the magnetic lines of force 
> interacting).
>
> It took me a few hours of contemplating and experimenting to figure this out. 
>  If someone has come up with a easy "fix", please let me know.  I tried 
> buying a steel plate (alum will definitely not work) at Home Depot and placed 
> that between the K3 and amp; it did nothing to fix the problem (or even 
> help).   One sure fire fix is to turn off the amp!
>
> Dick K8ZTT
>
>
>
>
> --- k6...@me.com wrote:
>
> From: Lew Phelps K6LMP 
> To: "Elecraft@mailman.qth.net List" 
> Subject: Re: [Elecraft] K3 Hum on Audio...
> Date: Thu, 02 Feb 2012 10:24:07 -0800
>
> Thank you, Tony!
>
> I had developed a maddening audio hum suddenly, and couldn't find the cause.  
> The curious thing was that it was WORSE when no mike was plugged into the 
> jack on the back panel.
>
> Based on your email, I checked the menu settings. Sure enough, MIC + LINE:  
> ON.  Switched to OFF and the hum totally disappeared. You don't need to 
> adjust the LIN volume; just cut it off entirely.
>
> Lew K6LMP
>
>
> On Jan 14, 2012, at 9:02 AM, N2TK, Tony wrote:
>
>> Make sure the LIN IN is not turned up. Early on I had a problem with hum in
>> my audio, especially if an amp was close to the K3. For some reason my LIN
>> IN was at max. Turned it down and hum went away.
>> 73,
>> N2TK, Tony
>>
>> -Original Message-
>> From: elecraft-boun...@mailman.qth.net
>> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Phil Hystad
>> Sent: Friday, January 13, 2012 12:54 PM
>> To: j...@audiosystemsgroup.com
>> Cc: elecraft@mailman.qth.net
>> Subject: Re: [Elecraft] K3 Hum on Audio...
>>
>> Jim,
>>
>> Well, I would call it mostly a buzz.  Also, the only near magnetic field of
>> the KPA500 power transformer is off, I mean powered off and unplugged, so
>> that does not seem to be the problem.
>>
>> I just ran another test with everything disconnected, including ground and
>> coax.  With the K3 in TEST mode, key-down on the mic still produces the hum.
>> I double checked the grounds.  I did this because if I were to touch
>> anything metal on the k3, the metal part of the PL259 or the ground strap,
>> the hum is damped quite a bit to almost insignificant.  It seems that if my
>> rig were already well grounded this would not happen so I am curious if this
>> is something I would normally expect.
>>
>> I will experiment with the TXEQ but this is a real puzzle I would like to
>> solve, not merely erase it.
>>
>> 73, phil
>>
>>
>> On Jan 13, 2012, at 9:37 AM, Jim Brown wrote:
>>
>>> On 1/13/2012 9:20 AM, Phil Hystad wrote:
>>>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500
>> mic as in the MH2 but it is present.
>>>
>>> Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly
>>> harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field
>>> coupling into the audio, either from a big power transformer (like the
>>> one in a power amp or a big linear power supply) or from a AC power
>>> wiring fault called a double-bonded neutral.
>>>
>>> The K3 has unshielded audio transformers at all the audio inputs and
>>> outputs, and an unshielded transformer is a sitting duck 

Re: [Elecraft] K3 Hum on Audio...

[Alan Bloom]

One trick I have used in the past is to put a copper strap around the
transformer.  It acts as a shorted turn for the radiated fields,
reducing their amplitude.  You could try that both on the power
transformer and on the audio transformer in the K3.  Of course, the
strap needs to be soldered so it makes a continuous loop.

Alan N1AL


On Fri, 2012-02-03 at 12:21 -0800, k8...@mho.com wrote:
> This is a "common" problem when a amplifer is placed next to the left
> side of the K3 (especially if the transformer in the amp is on the
> rigt side - like the Alpha amps).
> 
> The problem is caused because the K3 line in has a isolation
> transformer conveniently located on the left side.  Place a power
> transformer next to it, and all hell breaks loose (something to do
> with the magnetic lines of force interacting).
> 
> It took me a few hours of contemplating and experimenting to figure
> this out.  If someone has come up with a easy "fix", please let me
> know.  I tried buying a steel plate (alum will definitely not work) at
> Home Depot and placed that between the K3 and amp; it did nothing to
> fix the problem (or even help).   One sure fire fix is to turn off the
> amp!
> 
> Dick K8ZTT
> 
> 
> 
> 
> --- k6...@me.com wrote:
> 
> From: Lew Phelps K6LMP 
> To: "Elecraft@mailman.qth.net List" 
> Subject: Re: [Elecraft] K3 Hum on Audio...
> Date: Thu, 02 Feb 2012 10:24:07 -0800
> 
> Thank you, Tony!
> 
> I had developed a maddening audio hum suddenly, and couldn't find the cause.  
> The curious thing was that it was WORSE when no mike was plugged into the 
> jack on the back panel.
> 
> Based on your email, I checked the menu settings. Sure enough, MIC + LINE:  
> ON.  Switched to OFF and the hum totally disappeared. You don't need to 
> adjust the LIN volume; just cut it off entirely.
> 
> Lew K6LMP
> 
> 
> On Jan 14, 2012, at 9:02 AM, N2TK, Tony wrote:
> 
> > Make sure the LIN IN is not turned up. Early on I had a problem with hum in
> > my audio, especially if an amp was close to the K3. For some reason my LIN
> > IN was at max. Turned it down and hum went away.
> > 73,
> > N2TK, Tony
> > 
> > -Original Message-
> > From: elecraft-boun...@mailman.qth.net
> > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Phil Hystad
> > Sent: Friday, January 13, 2012 12:54 PM
> > To: j...@audiosystemsgroup.com
> > Cc: elecraft@mailman.qth.net
> > Subject: Re: [Elecraft] K3 Hum on Audio...
> > 
> > Jim,
> > 
> > Well, I would call it mostly a buzz.  Also, the only near magnetic field of
> > the KPA500 power transformer is off, I mean powered off and unplugged, so
> > that does not seem to be the problem.
> > 
> > I just ran another test with everything disconnected, including ground and
> > coax.  With the K3 in TEST mode, key-down on the mic still produces the hum.
> > I double checked the grounds.  I did this because if I were to touch
> > anything metal on the k3, the metal part of the PL259 or the ground strap,
> > the hum is damped quite a bit to almost insignificant.  It seems that if my
> > rig were already well grounded this would not happen so I am curious if this
> > is something I would normally expect.
> > 
> > I will experiment with the TXEQ but this is a real puzzle I would like to
> > solve, not merely erase it.  
> > 
> > 73, phil
> > 
> > 
> > On Jan 13, 2012, at 9:37 AM, Jim Brown wrote:
> > 
> >> On 1/13/2012 9:20 AM, Phil Hystad wrote:
> >>> Unfortunately, it is in both mics but not as strong in the Yamaha CM500
> > mic as in the MH2 but it is present.
> >> 
> >> Clarification question.  Is it HUM (pure 60 Hz), or BUZZ (mostly 
> >> harmonics of 60 Hz)?  If it's HUM, I would suspect magnetic field 
> >> coupling into the audio, either from a big power transformer (like the 
> >> one in a power amp or a big linear power supply) or from a AC power 
> >> wiring fault called a double-bonded neutral.
> >> 
> >> The K3 has unshielded audio transformers at all the audio inputs and 
> >> outputs, and an unshielded transformer is a sitting duck for magnetic 
> >> fields.
> >> 
> >> The good news is that the K3 has excellent audio equalization (TXEQ) 
> >> that allows us to remove that 60 Hz hum by filtering.  The lower audio 
> >> frequencies in the human voice make NO useful contribution to speech 
> >> intelligibility, but they do waste transmit power. So it is ALWAYS a 
> >> good thing to set the TXEQ for maximum cut of the lo

Re: [Elecraft] K3 Hum on Audio...

[Jim Brown]

On 2/3/2012 12:43 PM, Guy Olinger K2AV wrote:
> This is an endemic "uncurable" problem.

Maybe not.  One mechanism I suspect, based on the symptom that it 
happens with the Line Input turned up, is magnetic coupling into the 
unshielded audio transformer on the Line Input. That coupling is nearly 
always pure 60 Hz, without harmonics, and is a well known problem.. In 
data modes, the Line Input is rolled off sharply at some frequency like 
200 Hz or so, which knocks the hum down by something like 18dB.. I 
recommend doing that for SSB too, because the lower octaves carry no 
intelligibility but can waste a lot of TX power.

The separation that matters this this case is the generator of the 
magnetic field, usually the power transformer for a big power amp, but 
it can also be caused by wiring errors in the power wiring in a home. It 
can help a lot to rotate the amp to put its field at right angles to the 
magnetic receiver (the audio transformer in the K3), and also to move it 
further away from the K3.

As to RFI with lines running past a computer -- I had that issue in 
Chicago, where I used a long wire antenna on 80 and 160, and it locked 
up the serial connection.  The culprit there was the K2 serial cable, 
which used PARALLEL wires inside a shield. I replaced it with TWISTED 
PAIRS without a shield, with one pair for each circuit used between the 
computer and the rig, with the return for each pair going to the chassis 
on each end, and the problem went away.  With the original cable, it 
locked up at 12 watts. With the twisted pair, I could run full power 
from my Titan 425.

73, Jim K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Guy Olinger K2AV]

Hi Jim,

For a price and/or sufficient work and enough expertise, it might be
possible to shield anything.  There is that mu-metal stuff. But mostly
that level of induction from something pulling that much current into
microphone level devices is a really really hard cure, hence
"uncurable" in quotes. For equipment that is sold at ham-affordable
prices, and where most people do not have the problem, and it is a
layout choice, the level of shielding would seem a good commercial
choice by manufacturers.

Again, if one considers all these issues when one is CHOOSING one's
station layout, you really do not have to kick all those dogs and put
yourself in the position in the first place.

I WOULD expect YOU to be able to cobble something to make it work in
spite of a station layout that kicks the dogs.  :>)   But for the rest
of us for which that is endless experimenting and not necessarily
knowing WHICH detail of the fix we messed up when we tried it, not
kicking the dogs at all, when we don't have to, is a very profitable
direction.

73, Guy

On Fri, Feb 3, 2012 at 11:27 PM, Jim Brown  wrote:
> On 2/3/2012 12:43 PM, Guy Olinger K2AV wrote:
>> This is an endemic "uncurable" problem.
>
> Maybe not.  One mechanism I suspect, based on the symptom that it
> happens with the Line Input turned up, is magnetic coupling into the
> unshielded audio transformer on the Line Input. That coupling is nearly
> always pure 60 Hz, without harmonics, and is a well known problem.. In
> data modes, the Line Input is rolled off sharply at some frequency like
> 200 Hz or so, which knocks the hum down by something like 18dB.. I
> recommend doing that for SSB too, because the lower octaves carry no
> intelligibility but can waste a lot of TX power.
>
> The separation that matters this this case is the generator of the
> magnetic field, usually the power transformer for a big power amp, but
> it can also be caused by wiring errors in the power wiring in a home. It
> can help a lot to rotate the amp to put its field at right angles to the
> magnetic receiver (the audio transformer in the K3), and also to move it
> further away from the K3.
>
> As to RFI with lines running past a computer -- I had that issue in
> Chicago, where I used a long wire antenna on 80 and 160, and it locked
> up the serial connection.  The culprit there was the K2 serial cable,
> which used PARALLEL wires inside a shield. I replaced it with TWISTED
> PAIRS without a shield, with one pair for each circuit used between the
> computer and the rig, with the return for each pair going to the chassis
> on each end, and the problem went away.  With the original cable, it
> locked up at 12 watts. With the twisted pair, I could run full power
> from my Titan 425.
>
> 73, Jim K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Jim Brown]

On 2/3/2012 9:25 PM, Guy Olinger K2AV wrote:
>There is that mu-metal stuff. But mostly
> that level of induction from something pulling that much current into
> microphone level devices is a really really hard cure, hence
> "uncurable" in quotes.

 From the symptoms, it was coming into the LINE INPUT -- he said the 
Line Input was cranked up and he turned it down or off and cured the 
problem.

Yes, mu-metal shielding cures the problem, but that's a lot more 
expensive than what's in the radio.  The real issue is that transformers 
are the wrong solution. All that is needed is simple chassis-to-chassis 
bonding between the equipment being interconnected. This sort of design 
error is  what happens when you assign digital guys to design audio 
circuits.  :)

73, Jim Brown K9YC
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Re: [Elecraft] K3 Hum on Audio...

[Eric Buggee]

Hi List Mates;
  For those who may not be aware regarding the 
copper strap around the transformer
(as Alan N1AL says) it acts as a shorted turn to external "H" fields 
make sure that the copper strap goes around the OUTSIDE of the windings 
as well as the core and NOT thru the window of the core where the 
windings go otherwise you will introduce a dead short circuit to the 
magnetic flux in the core which will short out the primary & blow the 
mains fuse(s).

Another approach is to make up a magnetic shield  of about 4 or 6 sheets 
of 0.020" (0.5mm) thick transformer core lamination steel; each sheet 
cut to about 6" (152.4 mm) square - or- the same size as the side panel 
of the linear am side panel tape them together and fit them inside the 
amp adjacent to the core of the power transformer- in particurlar if the 
gap between the two halves of the "C" cores is facing toward the side of 
the linear amp.

The sheets of transformer core steel will shunt the stray (leaking) 
magnetic field emanating from the two faces of the "C) cores. Will work 
the same for the junctions of the "E's & I's of a conventional E&I built 
transformer (although there is more stray magnetic field from 
transformers of E&I construction.
Lowest stray magnetic leakage is from transformers using toroidal core 
construction.

Hope this information is of use.

Eric VK3AX. K34250.



On 2/4/2012 7:51 AM, Alan Bloom wrote:
> One trick I have used in the past is to put a copper strap around the
> transformer.  It acts as a shorted turn for the radiated fields,
> reducing their amplitude.  You could try that both on the power
> transformer and on the audio transformer in the K3.  Of course, the
> strap needs to be soldered so it makes a continuous loop.
>
> Alan N1AL
>
>
> On Fri, 2012-02-03 at 12:21 -0800, k8...@mho.com wrote:
>> This is a "common" problem when a amplifer is placed next to the left
>> side of the K3 (especially if the transformer in the amp is on the
>> rigt side - like the Alpha amps).
>>
>> The problem is caused because the K3 line in has a isolation
>> transformer conveniently located on the left side.  Place a power
>> transformer next to it, and all hell breaks loose (something to do
>> with the magnetic lines of force interacting).
>>
>> It took me a few hours of contemplating and experimenting to figure
>> this out.  If someone has come up with a easy "fix", please let me
>> know.  I tried buying a steel plate (alum will definitely not work) at
>> Home Depot and placed that between the K3 and amp; it did nothing to
>> fix the problem (or even help).   One sure fire fix is to turn off the
>> amp!
>>
>> Dick K8ZTT
>>
>>
>>
>>
>> --- k6...@me.com wrote:
>>
>> From: Lew Phelps K6LMP
>> To: "Elecraft@mailman.qth.net List"
>> Subject: Re: [Elecraft] K3 Hum on Audio...
>> Date: Thu, 02 Feb 2012 10:24:07 -0800
>>
>> Thank you, Tony!
>>
>> I had developed a maddening audio hum suddenly, and couldn't find the cause. 
>>  The curious thing was that it was WORSE when no mike was plugged into the 
>> jack on the back panel.
>>
>> Based on your email, I checked the menu settings. Sure enough, MIC + LINE:  
>> ON.  Switched to OFF and the hum totally disappeared. You don't need to 
>> adjust the LIN volume; just cut it off entirely.
>>
>> Lew K6LMP
>>
>>
>> On Jan 14, 2012, at 9:02 AM, N2TK, Tony wrote:
>>
>>> Make sure the LIN IN is not turned up. Early on I had a problem with hum in
>>> my audio, especially if an amp was close to the K3. For some reason my LIN
>>> IN was at max. Turned it down and hum went away.
>>> 73,
>>> N2TK, Tony
>>>
>>> -Original Message-
>>> From: elecraft-boun...@mailman.qth.net
>>> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Phil Hystad
>>> Sent: Friday, January 13, 2012 12:54 PM
>>> To: j...@audiosystemsgroup.com
>>> Cc: elecraft@mailman.qth.net
>>> Subject: Re: [Elecraft] K3 Hum on Audio...
>>>
>>> Jim,
>>>
>>> Well, I would call it mostly a buzz.  Also, the only near magnetic field of
>>> the KPA500 power transformer is off, I mean powered off and unplugged, so
>>> that does not seem to be the problem.
>>>
>>> I just ran another test with everything disconnected, including ground and
>>> coax.  With the K3 in TEST mode, key-down on the mic still produces the hum.
>>> I double checked the grounds.  I did this because if I were to touch
>>> anything metal o