Good point! I got this advice from someone earlier...but it wasn’t the UPS. Nor
was it anything else in my QTH domain. It comes and goees but does not bother
me too much. Part of the problem is the Flex panadaptor shows you stuff that’s
there but you were aware of. Drives you crazy, but not a major nuisance.
When trying to track down on-site QRM/QRN by using the trip-breaker technique,
it gets dicey powering stuff (Flex + Monitor + PC) unless you have a totally
portable station. I have a Flex 5000 I run with a PC/Monitor. AFAIK they are
all “clean”, but running them 100% off the power grid is problematic. When I
substitute a battery or alternate PC, I have perhaps killed one noise source
but introduced a new one.
I will worry about it when these noise humps are S9+. Right now they are below
–115dM, not on all bands, and are just annoyances.
73
Dan
K0DAN
From: Bob Kay
Sent: December 01, 2012 07:48 PM
To: K0DAN
Cc: flexradio@flex-radio.biz
Subject: Re: [Flexradio] Sweeping noise/signal across band
Check your UPS supply. You've described my situation exactly. I contacted UPC
and they had no interest in solving it. Unplugged the UPS and the problem is
gone.
On Saturday, December 1, 2012, K0DAN wrote:
There can be many sources of this. First and easiest thing to do is find out
if you're the cause of your own noise.
If possible, power your Flex from a battery or UPS, and use a laptop under
battery power as the PC. Then turn off all circuit breakers at your QTH and see
if anything changes. The breaks will kill any vampire power from your QTH
(power supplies, wall warts, HVAC fans, etc.). If the noise changes or goes
away, now start turning circuits back on and see what brings back the noise. At
that point you can better ID the source and look for mitigation.
If tripping your breakers doesn't do it, it's your neighbors and/or in your
environment, and might not be feasible to identify or resolve, esp in FL condo.
GL es 73
Dan
K0DAN
-----Original Message----- From: Steve Fowler
Sent: December 01, 2012 04:15 PM
To: flexradio@flex-radio.biz
Subject: Re: [Flexradio] Sweeping noise/signal across band
Welcome to urban noise pollution! At least that's my best guess. I have
switch mode power supplies in my house along with the PWM motor controller
on my furnace that make noise like that. The one I had that acted exactly
like yours was a SMPS powering my security cameras. The frequency changes
with minor variations in the load, which causes the drifting you see, and
the long wires feeding my cameras make great transmitting antennas. You
can track down and reduce or eliminate the noise coming from your own
house, but then you'll start picking it up from the neighborhood and beyond.
On Sat, Dec 1, 2012 at 3:50 PM, konrad schultz <konra...@hotmail.com> wrote:
Anyone having a similar problem. I see (on the panafall) and hear in the
headphones a sweeping signal or noise that regularly and slowly goes across
the band in time. Right to left and then back. Adds 20 db of noise to a
-119 db threshold on 20M CW. I am using my FLEX 3000 portable here at our
condo in SW FL. Ant is a portable dipole mounted on a camera tripod using
two MFG 20M whips and stands 3-6 feet off the ground. 50 Ohm coax. New
Lenovo laptop. All seemed to work fine at our QTH up north on 80M dipole -
which is up in two trees. Thoughts? Best, Konrad W1KON
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--
Best 73 de WA2SQQ
Elmwood Park, NJ
"The only dumb questions are those we don't ask"
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