[Hackrf-dev] Amp On or Off

[Paul Connolly]

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
> HackRF-dev at greatscottgadgets.com
> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 834 bytes
Desc: OpenPGP digital signature
URL: <https://pairlist9.pair.net/pipermail/hackrf-dev/attachments/20150701/9dde1613/attachment.pgp>