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10620Re: [loopantennas] Ala 100la antenna question

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  • Andrew Ikin
    Jun 10 2:12 PM
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      John,
       
      The active portion is in the Head Amp., so it doesn’t matter which interface you use. The exception to this is with the ALA1530S+ and the ALA330S which have a 2 transformer Balanced Norton amplifier ( 2 x 2N4401 ) in the Interface to provide an extra 9dB gain with a +55dBm OIP3.
       
      Btw, it was one of Chris Trask’s papers that suggested the 2N4401 for exceptional linear applications! However, the On semiconductor manufacture appears to be the best. Unfortunately the complement On Semi 2N4403 (T092) is now obsolete.
       
      Kind regards
       
      Andrew
       
      Sent: Tuesday, June 10, 2014 8:31 PM
      Subject: Re: [loopantennas] Ala 100la antenna question
       
       

      Hi Andy understood, but the actual active antenna portion or the "active antenna head" doesn't matter if it's getting the older -ve center voltage setup or the newer +ve center voltage setup.  Is that correct?

      Sent from my iPhone

      On Jun 10, 2014, at 2:25 PM, "Andrew Ikin andrew.ikin@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

       
      John,
       
      The polarity of the Interface and power supply must be the same. If you get it wrong the series diode on the older interface (-ve inner) will protect the loop from a reverse voltage. The newer (+ve inner) has a protection diode that will pull the resettable fuse.
       
      Kind regards
       
      Andrew
       
       
      Sent: Tuesday, June 10, 2014 5:40 PM
      Subject: Re: [loopantennas] Ala 100la antenna question
       
       
      Thanks Andy!!   You're right I forgot all about the voltage feed.   Glad I asked.  While I have your ear. I have an older wellbrook " - center" power supply and I have a newer + center power unit.  Is it true that I can use either of these with the antenna unit as long as I have the polaritys correct on the power unit  I.e.  - center walkway with negative center power unit. + center power unit with positive center power unit

      Sent from my iPhone

      On Jun 10, 2014, at 12:19 PM, "Andrew Ikin andrew.ikin@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

       
      Hello John,
       
      Under no circumstances use 300 Ohm twin lead.
       
      There are 3 issues to consider:
       
      A reverse polarity on the feeder would damage the head Amp.
       
      If you get it to work, there may be instability.
       
      The feeder will be un-balanced and pick up local noise.
       
      Kind regards

      Andrew

      Andrew Ikin e-mail: sales@...
      andy@...
      URL: http://www.wellbrook.uk.com

      Wellbrook Communications

       
      Sent: Tuesday, June 10, 2014 4:49 PM
      Subject: [loopantennas] Ala 100la antenna question
       
       

      Hi. I have a wellbrook ala100. La (large aperture) loop antenna. I purchased this about 3 or 4 years ago and I'm finally getting around to really using it. My question is can I feed it with 300 ohm twin lead??. I have two rolls of this lead in and I would like to put it to good use instead of purchasing coax. Thankyou. John

      Sent from my iPhone

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