Topband: Nasty QRM From ??

[Dick Bingham]

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