Loading ...
Sorry, an error occurred while loading the content.
 

Re: [perseus_SDR] Re: VLF reception on Perseus

Expand Messages
  • Jurgen Bartels
    ... 1. use a transformer that doesn t cut off LF, like the torroid I used to use I now use binocular core BN 73-202 50 ohm side has 4 turns, 450 ohm side: 12
    Message 1 of 46 , Feb 1, 2011
      > Jurgen, you say that you enabled your Beverage to tune VLF.  May I ask how you
      > did that?  Thanks!  ..........Walt Salmaniw, Victoria, BC

      1. use a transformer that doesn't cut off LF, like the torroid I used to use
      I now use binocular core BN 73-202
      50 ohm side has 4 turns,
      450 ohm side: 12
      There's a compromise,
      4 turns: freq above 3Mhz start to drop off
      3 turns: freq above 3Mhz do NOT drop off, but below 200kHz drop off
      I use 4 turns
      I did not want to use a VLF-only optimized transformer as my main
      interest is MW

      2. replaced the 220V PC-PSU connector against one with built-in mains filter.
      That eleminated most LF noise that went to the antenna

      3. use chokes at the antenna feed side and right at the rx input
      see example here http://dx.3sdesign.de/antenna_selector.htm

      Here's a 7h plot of 18-26 kHz
      http://dx.3sdesign.de/temp/Spectr-110128-2343_18-26kHz.jpg

      you see 24kHz-Cutler,ME and 25,2kHz-N-Dakota fade in,
      while 19,8-Australia is there all the time
      24,8-Oso,WA is absent


      See fx here:
      http://www.mwlist.org/vlf.php

      Jurgen Bartels Suellwarden, N. Germany
      hor. Antennas: 11-ele 45-87MHz 13-ele Band-III, 48-ele UHF, FM: 15.11
      TV: Winradio G305 / Fly2000 + video noise filter & variable IF BW
      FM: Downconverter + Perseus + Speclab as WFM demod.
      MW: staggered 300m Beverage 320°, 30 x 4m EWE 320°, Winradio & Perseus
      http://dx.3sdesign.de/tv_offset_list.htm
      http://dx.3sdesign.de/station_list.htm

      http://fewo.3sdesign.de - Vacation home: DX right at the Northsea coast
    • Jurgen Bartels
      ... Thanks Roelof & Marco I wasn t aware of that. Adding to that the 2 transformers I use, the resulting attenuation gets quite large below 10kHz. I have to
      Message 46 of 46 , Feb 7, 2011
        > >Perseus has a rf isolating transformer at the input which acts as a
        > >high pass filter.
        > >Sensitivity drops below 15 kHz.
        >
        > the Perseus frequency response is in the files section of the grup.
        > Look in the root, "Perseus frequency response.pdf" - it is a typical
        > curve, there is of course no warranty from Nico, but it should give
        > an idea of the rolloff.
        > At 10 kHz it is only 8 dB down with respect to 200 kHz, and if you
        > want to use it for the "dreamers band" VLF DX (5.7 and 9 kHz, see the
        > RSGB LF group), well, it may work :-)

        Thanks Roelof & Marco

        I wasn't aware of that.
        Adding to that the 2 transformers I use, the resulting attenuation gets quite
        large below 10kHz. I have to see if I can get the next dreamer transmissions.




        Jurgen Bartels Suellwarden, N. Germany
        hor. Antennas: 11-ele 45-87MHz 13-ele Band-III, 48-ele UHF, FM: 15.11
        TV: Winradio G305 / Fly2000 + video noise filter & variable IF BW
        FM: Downconverter + Perseus + Speclab as WFM demod.
        MW: staggered 300m Beverage 320°, 30 x 4m EWE 320°, Winradio & Perseus
        http://dx.3sdesign.de/tv_offset_list.htm
        http://dx.3sdesign.de/station_list.htm

        http://fewo.3sdesign.de - Vacation home: DX right at the Northsea coast
      Your message has been successfully submitted and would be delivered to recipients shortly.