Dick, if you have a portable AM radio, try sniffing around your power meter and
any cable leads (tv, internet) that are coming into the house ... while you
have main breaker pulled.
If nil then start a search in the local neighbourhood making note of where it
gets louder. You should eventually trace the source this way. I’ve done it here
on several occasions and have found sources as far as several blocks away. This
crud travels along power lines using them as antennas. A couple of sources
turned out to be burned out or failing CFL lights. Once located, a friendly
chat with the source owner has always solved the problem. Good luck with the
search.
Steve VE7SL
----- Original Message -----
From: k8bhz@alphacomm.net
To: Dick Bingham <dick.bingham@gmail.com>, Topband@contesting.com
Sent: Fri, 24 Jan 2020 10:20:06 -0700 (MST)
Subject: Re: Topband: Nasty QRM From ??
Just a thought, does your house have the new "intelligent" power
metering on the powerline? This would still be on, even if your breakers
were off. Or, maybe the same type of monitoring on natural gas or
municipal water supplies. Sure sounds like a switching power supply....
Brian K8BHZ
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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