Antenna Choices


In addition to my KiwiSDR use, I have been doing similar stuff with Perseus for a few years. I have evaluated many antennas. The Clifton whip is a great antenna but I found it to be susceptible to VHF/UHF overload from the many TV/FM stations 1/2 mile from me. I have tried Wellbrook (older), Pixel (now DX Eng.), W6LVP and now MFJ loops.  The Pixel is my first choice while the W6LVP and MFJ follow closely behind.  More details in the future. 

Comments

  • Hi James,

    You should be able to fix the FM BC interference problem that you have with the Clifton whip.

    Three or four turns on a small single hole ferrite bead in series with the connection from the whip to the amplifier should do it. If not add an additional 1 to 2 K Ohm resistor also in series with the bead. This will roll off the VHF gain quite substantially without too much impact on the HF bands.

    I used a similar active whip antenna for the MF band on our SUWS WEB SDR, where we had a 25w VHF DMR base station antenna about 3m away from the whip and it fixed the problem.


    Regards,

    Martin - G8JNJ
  • The interference is the OV of the whip's own active device, not downstream.
  • WebSDR's creator P.T. de Boer, PA3FWM, has an excellent article about how to add an LPF to the tricky super-high-impedance E-field probe of an active antenna: http://www.pa3fwm.nl/technotes/tn05.html#lpf

  • Thanks!
  • more on Loops...

    The Pixel/DX Eng. uses a 24VAC wall wart whereas the other 2 use 12VDC or lower supplies.  The higher voltage suggests a better (higher voltage) drain supply and and better big signal performance.  Measuring things like the IMD etc of the preamp would confirm but I don't intend to do a bench eval of them.  
  • Hi James,

    You misunderstand, my suggestion was to place the ferrite bead and resistor at the amplifier input (in series with the whip) as shown in the link that was later posted by John. 


    This method works very well.

    Regards,

    Martin - G8JNJ



  • OK.... well the whip is in my review mirror so....  will keep it in mind for the future
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