ON4IQ

50MHz Preamp testing

On several occasions there have been discussions about the use of preamps on six meters. A lot of people consider it a waste of time/money seen the high noise floor on 6m. So I've made a simple test set up to get some real data.

Setup:

3el yagi 6m agl, 6m preamp (custom ssb electronics), Dientronik 40-80MHz downconvertor , Perseus SDR

Software:

HF span and CW Skimmer

Referency frequency:

50021.9 (LX0SIX beacon)

Results:

Noise floor no preamp: -107.3 dB, SNR of the beacon 22dB measured in 150Hz BW

Noise floor with preamp: -85.0dB, SNR of the beacon 24dB measured in 150Hz BW

Noise floor with preamp and extra bandpass ater preamp: -85.7dB, SNR of the beacon 24dB measured in 150Hz BW

Conclusion:

preamp adds 22.3dB gain , and improves SNR with 2dB for this given setup (preamp has better noise figure than the downconvertor)

So its worthwhile to test if a preamp will improve the setup. Next test will be with ftdx5000 and preamp

 


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