[Hackrf-dev] Problem with RF amplifier at UHF

[MA]

Hi
I'm trying to run a GPS simulator on my HackRF.
Here's the link to the project: https://github.com/osqzss/gps-sdr-sim
The author (and another user) have managed to run this successfully on a
HackRF (although he says HackRF has a problem of clock unstability, but it
still can be used)
He uses a 20dB attenuator at the output (with ANT500) and the signal
strength on his Android GPS diagnostics app is about 40.
I don't use an attenuator and still my signal strength rarely reaches 30 !
What could be wrong with my HackRF?
FYI, I've installed a RF shield and a heatsink (bought from NooElec), but I
doubt they have anything to do with TX power.

Thanks
Mehdi
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