If your really paranoid, hang a 3 to 6 db pad on the input. Then you can try the preamp to see what it does to the signal.
Do this a lot, as I'm always interested in seeing what the preamp provides - pads are cheap. --eddie On Wed, Jul 1, 2015 at 1:34 PM, Paul Connolly <[email protected]> wrote: > If you look at the bottom right hand corner of the third page (the > HackRF One front end) of > > https://github.com/mossmann/hackrf/blob/master/doc/hardware/hackrf-one-schematic.pdf > > The SMA antenna (P4) is followed by a transient-voltage-suppression > diode to protect the circuit (ESD), which is followed by the Bias-T > blocking capacitor (C64), then it enters a single-pole triple-throw > switch (U14 - SKY13317), there are three possibilities: > The TX amp (U25) is connected to the Antenna. > The bypass path is connected to the Antenna. > The RX amp (U13) connected to the Antenna. > > The symptom of a blown amp is that when it is switch into the signal > path it acts like an attenuator (lower SNR) instead of a providing gain, > relative to it being bypassed. So you will see a higher SNR with the amp > bypassed. > > On 01/07/2015 16:02, Daniel Bernhardt wrote: > >> Now the amp is presumed blown it acts more like an attenuator, i.e. > signals are weaker with it switched on. > > Not regarding your specific case: > > Is there a definitive way to determine if ones preamp is blown or not? > For all we know it could be a faulty antenna setup or a cabling issue. Is > the amp completely bypassed if turned off or just not amplifying? What are > the symptomps of a "blown" amp? Does it short or are there signals coming > through much weaker due to some cuppling effects? > > Forgive my ignorance on the matter. Just beeing curious. > > > > Daniel > > _______________________________________________ > > HackRF-dev mailing list > > [email protected] > > https://pairlist9.pair.net/mailman/listinfo/hackrf-dev > > > > _______________________________________________ > HackRF-dev mailing list > [email protected] > https://pairlist9.pair.net/mailman/listinfo/hackrf-dev > >
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