I see you mentioned you checked everything with the power off. I would look at
utility poles maybe cable or fiber power supplies?? Also I have have had my sdr
settings not correct and have seen what I thought was QRM... Maybe try another
receiver? Good luck Fred KB4QZH
-------- Original message --------From: Artek Manuals
<Manuals@ArtekManuals.com> Date: 1/24/20 9:17 AM (GMT-05:00) To:
topband@contesting.com Subject: Re: Topband: Nasty QRM From ?? DickThere 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 possibleDaveNR1DXOn
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> _________________> Searchable Archives:
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