[Elecraft] Re: Noise level on 160m

[kc4kgu@ENTERZONE.NET]

On Mon, 25 Nov 2002, Dave Sergeant wrote:

> On 25 Nov 2002 at 4:01, LA3ZA wrote
> 
> > I notice that the band is very noisy, but my K2 behaves in a strange way as
> > I have to work it with the Attenuator on and RF gain in the 10 or 11 o'clock
> > position to get rid of a kind of noise that makes it almost impossible to
> > copy anything. The Noise Blanker makes it a little bit easier, otherwise the
> > RF gain has to be turned down even more. The noise seems to come as the RF
> > gain crosses a threshold and then it will distort the received CW also. To
> > me it seems like some sort of overload or oscillation in the RF/IF part of
> > the receiver. I have also noticed this kind of behavior on 80 m from time to
> > time.
> 
> I also suffer from very similar noise on top band and to a lesser 
> extent on 80m. I had originally thought it was local noise to me (and 
> was certainly not there some years ago when I was more active on the 
> band). It is certainly not generated internally in the K2 and was 
> completely absent when we used my K2 in the RSGB Field Day in June. 
> It is also usually absent during daytime and the early morning hours. 
> I rather suspect it is from the increasing use of computer and TV 
> devices (ADSL springs to mind as well).

A month or so ago, I chased a noise on 75/80 + 160m here at my
shack.  Strangely, for the first two days or so, I thought that it was
atmospheric garbage or that the band(s) were just poo-poo.  It sounded
like a wind storm on the K2 and on the TS-2000.

Then, one night, I was monitoring the 75m wind storm while I was working
on some power runs (installing some new lighting) in the house.  I wasn't
sure which breaker was which (they're now labled) so, I simply broke out
the flashlights and killed the main power.  The shack has a large battery
for backup so, the radios stayed on.  Much to my amazement, the "wind
storm" went away and the band was VERY good.

After I completed the electrical work, I started tracking the noise source
down.  I live about 500yds from a sub-station and I had this sinking
feeling that I was going to be in for a long drawn out battle with the
folks at AEP over something at the sub-station causing noise on the lines.

I grabbed my portable receiver and walked outside.  The noise was louder
on the ground floor then in the basement where the shack was.  I was
getting even sicker.  Then, as I walked towards the sub-station, the noise
got softer.  The further I got from the house, the less noise I heard.

I finally tracked the circuit that was causing the noise down to my
upstairs office.  Then it dawned on me.  A week earlier, I had brought a
"retired" machine home from our datacenter to use in the office.  I hadn't
been on the air for a couple of days after bringing the machine home so,
the "cause and effect" relationship didn't stick out in my mind.

I turned the office breaker back on - the noise came back.  I powered the
computer down and the noise went away.  It was the computer.

I haven't powered it back up since then.  I'm fairly certain it is the
power supply.  You can literally hear the HD spin up on the air when it is
powered up.

So, if you have introduced something new to your environment, look
there.  I've not had PC noise issues ever before.  I've even operated
portable from just outside of our datacenter with no issues.  This one
machine caused quite a racket though!

I'm just glad it wasn't the refrigerator or heat pump!

73 de John - K4WTF