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
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
