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

Re: [loopantennas] Re: LOOP AMPLIFIER

Expand Messages
  • brian nsl
    John, Thank you for the response to my query, most kind. Your 25mm x 3mm flat strip I make equivalent to the surface area of an 18mm dia tube in RF skin terms
    Message 1 of 10 , Jun 6, 2013
    • 0 Attachment
      John,
              Thank you for the response to my query, most kind.
      Your 25mm x 3mm flat strip I make equivalent to the surface area of
      an 18mm dia tube in RF skin terms which is about the same diameter
      as Welbrook use for the ALA-1530 !!!!
      Certainly our local DIY warehouse sells strip in 3m long lengths so
       will check out the cross sections available.
      From your clear description assembly sounds straightforward,
      the secret being not to lose the wire tail hi!
      As a matter of interest I had similar thoughts on using a 3ft dia plastic
      ' Hula Hoop ' with  rolled up turkey strength cooking foil as the core
      these are just the correct dia to fit into PVC 18mm electrical conduit
      fittings like ' T's, junction boxes, elbows etc ' which has the advantage
      of being much stronger than PVC water pipe.
      To date I have never  heard of anyone who has taken a Wellbrook ALA-1530
      apart !!!!! 
      I will let you know how I fare with my version of the loop.
      My particular interest is NDB and 28 mhz beacon monitoring.
      Your comments on nulling the local ' pest ' out is of much interest
      as I have 349.5 khz - Liverpool just 8 miles away, a real pain !!!!!
                                                Regards,
                                                     72, Brian, G├śNSL.
      ----- Original Message -----
      From: john
      Sent: Thursday, June 06, 2013 1:02 PM
      Subject: [loopantennas] Re: LOOP AMPLIFIER

       
    • Andrew Ikin
      Brian wrote on June 6. Your 25mm x 3mm flat strip I make equivalent to the surface area of an 18mm dia tube in RF skin terms which is about the same diameter
      Message 2 of 10 , Jun 7, 2013
      • 0 Attachment
        Brian wrote on June 6.
         
         
        "Your 25mm x 3mm flat strip I make equivalent to the surface area of
        an 18mm dia tube in RF skin terms which is about the same diameter
        as Welbrook use for the ALA-1530 !!!!"
         
         
        Brian,
         
        The loop amplifier in question has a very low input impedance, hence there will be a miss-match at MF and HF when using a loop with the above dimensions. Whilst this may not be an issue for just nullinng out a pest. There will be noticeable loss in s/n compared to Pixel and Wellbrook loops that use higher input impedance amplifiers.
         
        A very low input z amp. requires a much lower reactance loop. This is not easy to achieve whilst maintaining a reasonable capture area.
         
        Earlier this year I received updated Calibration data for the LFL1010 ( same amp as the 1530, but a much lower input z ) and compared it to the ALA1530. The net result was an approx. 10dB improvement is sensitivity at MF and HF with the higher input z ALA1530.
         
        Kind regards
         
        Andrew
         
      Your message has been successfully submitted and would be delivered to recipients shortly.