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Novice question re spurs

Posted: Sun Jul 21, 2019 12:36 am
by bconwell
I fired up the spectrum analysis software (latest version) on my RSP 2. I had some funny signals. In the course of tracking them down, I disconnected the antenna, and the signals persisted.

In the FM BCB band I get what look like FM signals at between -100 and -110 dBm.

More curious are 7 spurs between 250 and 375 MHz , all stronger than -90 dBm.

One spur, at 360 MHz, is at -58 dbm - even if I narrow sweep just to 359.99 to 360.01 MHz, with Ref level at -30 and range set to 100 dBm. It's an impulse-like filter, with nearby frequencies all at -120 dBm.

(A GIF screenshot is attached.)

Not what one expects with the antenna disconnected...

I tried some ferrites on the USB line, and they may have helped marginally, but spurs are still loud and clear.

Any ideas?


/Bill, K2PO
Portland, Oregon

Re: Novice question re spurs

Posted: Sun Jul 21, 2019 12:46 am
by bconwell
'Should have read

...It's an impulse-like signal...

attached is another screenshot - a 500 MHz sweep, again with no antenna connected.

/Bill, K2PO

Re: Novice question re spurs

Posted: Thu Jul 25, 2019 3:25 am
by bconwell
Do others see similar spectra with no antenna connected? Or is my device unique in this behavior?

/Bill, K2PO