Re: FDM-DUO overload issues


Clint Chron
 

Hi Steve,

 

Is your “PK” light coming on solid on the upper right corner of your Duo’s display.  That indicator will come on with a single -9 dbm signal.  It does not matter if the offending signal is in-band or adjacent band since the Duo has no front-end band pass filters.  The PK light means that the offending signal is strong enough to overload the ADC chip in the radio.  Multiple signals at low signal levels can also turn on the PK light.  At my QTH, I have about 10 high power AM broadcast stations that have signal levels from -50 dbm to -30 dbm.  Those stations will turn on my PK light unless I enable the Duo’s attenuator.  I can also turn off the PK light by inserting an AM high pass filter on the antenna jack or a band pass filter.

 

If your PK light is not coming on, then you could have some sort of other problem that is not necessarily related to a strong signal level.   A local ham station would have to be very close to your QTH and would have to be running a lot of power in order to cause in-band or adjacent band overload.

 

73

Clint

W7KEC

 

From: EladSDR@groups.io [mailto:EladSDR@groups.io] On Behalf Of Steve Knell
Sent: Wednesday, May 27, 2020 11:34 AM
To: EladSDR@groups.io
Subject: Re: [EladSDR] FDM-DUO overload issues

 

I only use standalone because I'm Linux only in the shack.  I send CAT commands to the FDM-DUO though, so I wonder if that QSF configuration is stored in the FDM-DUO or the QSF unit or on the PC...

If Elad publish the CAT commands required to program the QSF unit I could give it a go, but I'm not 100% sure that bandpass filters will solve the issue...

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