Hi Stefan, Roelof, Albert, Markus.

Thanks for the info.
So between 50 dB en 90 dB … That’s quite a range.
I _think_ it is more than 50 dB, but most certainly not in the 80-90 dB range, alas. Not with the amount of man-made noise I see here on HF, although on 137 I only hear (white) noise and some QRN. On HF it is S8 white noise + an enormous amount of other man-made QRM, sometime peaking to 9+20.
I will build a 40 dB attenuator to expand the range I can measure with the 897 to approximately 80 dB, I think this will be enough…

Regards,
Minto pa3bca.

 

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Ceterum censeo Carthaginem delendam esse

Hello Albert,

That's quite good.
Today it is just 50 dB in 1 Hz here. I have extended my wideband screen to display DCF39 and HGA22, bottom of http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_LF_DX_Grabber.html

In my RX there is a band pass filter with unknown attenuation at 138.83 kHz. I estimate it is 15...20 dB. But it changes when the antenna becomes wet :-/ Somehow i think there is a stable and equal distributed noise level here in the city that limits the sensitivity. But i've learned a bit more in the last weeks and will investigate things further...

73, Stefan/DK7FC

Am 08.08.2011 10:27, schrieb Albert:

Hi Minto, Roelof, Stefan es others,

 

The difference between DCF39 and the noise floor on a quiet day is 92 dB in 1 Hz (JO33DE) Antenna "inv L" 18m V and 34m H

 

73, Albert