[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 <jim at audiosystemsgroup.com>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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