Topband: Speaking of noise...

[Bob K6UJ]

David,

I think the "divide and conquer" approach is the best.  Hopefully the source(s) are in your own home, much easier 
to resolve.  What I did was to connect a 12 volt battery to my K3 so I could listen without needing AC.  Then shut off the main 
breaker to the house.  The noise was gone (yay!)  Then one at a time turned on each individual breaker until the noise started again.
Then went around and unplugged everything one at a time on that circuit until the noise went away.  I discovered I had two circuits with
noise offenders.  One was a Mikita battery charger for a battery powered drill in the garage.  The second was a DirecTV receiver.  It was the worst.
Even though it was turned off it radiated noise because the power supply is on all the time. ( So it is best to unplug everything when testing !)   I called DirecTV
and they acknowledged that some of the receivers can have RFI issues.  They sent me a new receiver in a few days and no more problem.  
I have  tried doing sleuthing with a portable AM radio but it wasn't effective at all, the AC lines conduct and radiate the noise so it is hard to nail down.
Hopes this helps and hope it is in your own home !

73,
Bob
K6UJ






On Dec 22, 2011, at 8:03 PM, D Rodman MD wrote:

> Here is my situation.  I am pretty sure noise is from switching power supplies. 
> Unfortunately, it tends to put noise right where I don't want it.  Like bottom of
> 160, 80 and 40m.  Typically the noise is 20-25 kHz of S8-9.  One hears
> modulations on it and the whole band moves up and down in frequency 15-25 kHz
> over many hours.  Best way to locate, inside house, outside house and correct?????
> 
> David J Rodman, MD
> 
> Assistant Clinical Professor
> Department of Ophthalmology
> SUNY/Buffalo
> 
> Office 716-857-8654
> 
> 
> 
> 
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK