N1MM+ SO2R on same band workflow and protection

Andy - KU7T

I find myself doing more SO2R with my 6600M. Condx are usually not good to actually use 2 bands, so I Run and S&P often on the same band in the 2 entry windows. I usually just keep the SO2R setting in N1MM+.

I understand that if I am on the same band, I have to be careful as FDX is usually enabled from an earlier true SO2R operation.  Do not want to damage my rigs front end.

I wish this workflow could be improved, I am just not exactly sure how.

Should the radio have a setting to explicitly allow FDX on the same band (in my case, I would always disallow it)?  It would be a good safety feature. 

I am also considering writing my own software to interrogate the radio and inhibit PTT if same band and FDX is on.  Does anyone know if this already exists?


73
Andy
KU7T

Mike-VA3MW

Hi Andy

Keep in mind, even though we may not have an active receiver on the display, RF energy can still flow down the antenna to the front end of the radio unless there is a physical disconnect between the antenna and the front end preamps.

The good news is that the Flex radios are really really well protected in the front end.  There are actually front end overload alerts that show up on SmartSDR and the Maestro is you are starting to approach that level.

I have only had 1 customer call me to tell me about it and he lived near an AM broadcast station, as in, across the street.

This should help.

39.4.3 High-Performance Analog to Digital Converter Block (ADC)

The ADC block, or digitizer, converts the received signals into digital data. All ADCs have overload points and damage points, but there is some variability in overload symptoms. With the FLEX-6000 Signature Series radios, the ADC overload point varies from +7dBm (FLEX-6300) to +9dBm (FLEX-6500 and FLEX-6700). This overload point is a “soft overload” meaning that at this point the receiver will begin to show a performance drop.

The ADC generally functions better with increasing signal levels up to this point. At the soft overload point, the receiver will begin to develop spurs that will appear in the panadapter and these spurs will grow as power is increased. A digital overload point will be reached around +12dBm (level varies by the receiver) at which point the receiver will cease to function normally, producing substantial distortion in received signals and rendering reception difficult.

At levels above +15dBm (level varies by receiver), the ADC can be damaged so the FLEX-6000 contains circuitry to disengage the ADC from the antenna. While circuitry should protect the radio from a damaging signal, it is highly recommended that station configuration be designed such that signal levels above the soft overload point are prevented from entering the antenna connector of the radio. FlexRadio Systems assumes no responsibility for damage incurred from high signal levels entering the receiver.

Mike va3mw