Dick
There are many sources that can generate this kind of "noise" . More
common of recent are variable speed blower motors in modern furnaces and
central A/C units. Next are cheap switch mode power supplies from a
plethora of items, manufactured in PRC. And finally outdoor lights that
come on at dark (Both LED and Mercury Vapor)
Since you have apparently killed all personal sources then it is likely
coming from a nearby neighbor I have had them come from 1/2 mile away
but not often . sources under a 1/4 mile are more likely. Tried� to look
at your QTH on google earth but since you have multiple QTH's that
wasn't possible
Dave
NR1DX
On 1/24/2020 1:59 AM, Dick Bingham wrote:
Greetings All
Here are my basic conditions:
- KiwiSDR (~DC-to-30MHz) or
- Apache-Labs 7000dle
- Dell laptop computer
- Both on battery power
I have cleaned up my system using chokes and filtering to the point
there are virtually no CM-signals entering the receiver when the feedline
at the antenna is disconnected and re-connected to a 50-ohm load.
When the antenna is reconnected I see desired signals PLUS an
unwanted comb-line with signals every ~98.4KHz (e.g. comb-lines span
2573.49KHz to 4355.38KHz resulting in 98.438KHz line spacings.)
These signals are frequency stable and not drifty. Shutting down the
house-mains with the receiver battery powered does not kill the QRM.
SO, it looks like something somewhere is generating this junk that
runs from
the BC-band to >20MHz.
Have any of you encountered similar ~98.xxxKHz spurious signals ?
73 Dick/w7wkr at CN97uj
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Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com
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