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Re: Remote_Tuned_Loop By Portstevos

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  • portstevos
    ... Hello, The Kyle schematic is for the main loop because when using varicaps with Kyle s design then there is no coupling loop. I have tried various
    Message 1 of 12 , Jul 5, 2007
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      --- In loopantennas@yahoogroups.com, "alamdamai1" <mwwong@...> wrote:
      >
      > Hi,
      >
      > I'm currently in the process of purchasing parts for fabricating the
      > loop that Portstevos had posted in the Files Section whereby i would
      > like to seek members further knowledge on the original Kyle KOLR
      > Remote-tuned Loop Pre-amp design....
      >
      > May i enquire is the loop as indicated in Kyle's schematic is
      > referring to the main loop or the smaller coupling loop? (pls refer
      > to filename loopdiagram1 for the schematic....)
      >
      > Reason being i would like to try out Kyle's design of using varactor
      > (tuning) diodes as a tuning capacitor for the main loop...
      >
      > However, if the loop in the schematic is referring to the main loop,
      > then i'm a bit confused at which point in the Pre-amp circuit board
      > do i solder the coupling loop feedline for signal pre-amplification
      > before going out to the receiver?
      >
      > best regards,
      >
      > Alan Wong
      >
      Hello, The Kyle schematic is for the main loop because when using
      varicaps with Kyle's design then there is no coupling loop. I have
      tried various experiments and variations of design such as varicaps
      onto the main loop with and without the pre-amp, I also tried using
      the varicaps to tune the main loop while using a coupling loop with
      and without the pre-amp and I have tried varicaps and pre-amp coming
      from the coupling loop.

      I don't know if I used the incorrect type of varicaps or if there are
      any better types available but I could not get anywhere near the same
      sensitivity and signal to noise ratio, peaking, bandwidth or 'Q' from
      any of the designs using varicaps in comparison to an old fashioned
      tuning gang on the main loop and the pre-amp on the coupling loop, it
      just seem's to be a magic combination for me and has proved to be
      reliable with excellant sensitivity and signal to noise ratio right
      across the frequencies it tunes which is from 2.3 up to 18 MHz (tuning
      to the lower frequencies below 4.7 MHz with the help of a remote
      switching relay to pull in extra capacitance across the main tuning gang!)

      I have also tried an old fashioned tuning gang on the main loop
      without a coupling loop with and without a pre-amp but the best
      performance still comes down to the design that has been posted.

      Best wishes from down under where it is freezing tonight!

      Michael S
    • mwwong@qbe.com.my
      Howday Mate..... thanks Michael for sharing with us on what you went through.... well, my MVAM108 has yet to arrive from the States and once i ve assemble the
      Message 2 of 12 , Jul 5, 2007
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        Howday Mate.....

        thanks Michael for sharing with us on what you went through....

        well, my MVAM108 has yet to arrive from the States and once i've
        assemble the board, will definately post it in this Group on its
        outcome....

        Alan Wong.




        "portstevos" <portstevos@...>
        Sent by: loopantennas@yahoogroups.com
        07/05/2007 06:40 PM
        Please respond to loopantennas

        To: loopantennas@yahoogroups.com
        cc:
        Subject: [loopantennas] Re: Remote_Tuned_Loop By Portstevos


        --- In loopantennas@yahoogroups.com, "alamdamai1" <mwwong@...> wrote:
        >
        > Hi,
        >
        > I'm currently in the process of purchasing parts for fabricating the
        > loop that Portstevos had posted in the Files Section whereby i would
        > like to seek members further knowledge on the original Kyle KOLR
        > Remote-tuned Loop Pre-amp design....
        >
        > May i enquire is the loop as indicated in Kyle's schematic is
        > referring to the main loop or the smaller coupling loop? (pls refer
        > to filename loopdiagram1 for the schematic....)
        >
        > Reason being i would like to try out Kyle's design of using varactor
        > (tuning) diodes as a tuning capacitor for the main loop...
        >
        > However, if the loop in the schematic is referring to the main loop,
        > then i'm a bit confused at which point in the Pre-amp circuit board
        > do i solder the coupling loop feedline for signal pre-amplification
        > before going out to the receiver?
        >
        > best regards,
        >
        > Alan Wong
        >
        Hello, The Kyle schematic is for the main loop because when using
        varicaps with Kyle's design then there is no coupling loop. I have
        tried various experiments and variations of design such as varicaps
        onto the main loop with and without the pre-amp, I also tried using
        the varicaps to tune the main loop while using a coupling loop with
        and without the pre-amp and I have tried varicaps and pre-amp coming
        from the coupling loop.

        I don't know if I used the incorrect type of varicaps or if there are
        any better types available but I could not get anywhere near the same
        sensitivity and signal to noise ratio, peaking, bandwidth or 'Q' from
        any of the designs using varicaps in comparison to an old fashioned
        tuning gang on the main loop and the pre-amp on the coupling loop, it
        just seem's to be a magic combination for me and has proved to be
        reliable with excellant sensitivity and signal to noise ratio right
        across the frequencies it tunes which is from 2.3 up to 18 MHz (tuning
        to the lower frequencies below 4.7 MHz with the help of a remote
        switching relay to pull in extra capacitance across the main tuning gang!)

        I have also tried an old fashioned tuning gang on the main loop
        without a coupling loop with and without a pre-amp but the best
        performance still comes down to the design that has been posted.

        Best wishes from down under where it is freezing tonight!

        Michael S




        [Non-text portions of this message have been removed]
      • dldorrance
        Hi Alan, Please see inline responses. Dave WA6YSO ... The pre-amp is placed on the main loop. The main loop (inductor) and capacitor (here a varactor setup)
        Message 3 of 12 , Jul 6, 2007
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          Hi Alan,

          Please see inline responses.

          Dave WA6YSO

          --- In loopantennas@yahoogroups.com, "alamdamai1" <mwwong@...> wrote:
          >
          > Hi,
          >
          > I'm currently in the process of purchasing parts for fabricating the
          > loop that Portstevos had posted in the Files Section whereby i would
          > like to seek members further knowledge on the original Kyle KOLR
          > Remote-tuned Loop Pre-amp design....
          >
          > May i enquire is the loop as indicated in Kyle's schematic is
          > referring to the main loop or the smaller coupling loop? (pls refer
          > to filename loopdiagram1 for the schematic....)

          The pre-amp is placed on the main loop. The main loop (inductor) and
          capacitor (here a varactor setup) forms a parallel resonant (tuned)
          circuit. In a small loop, the coupling loop is half of a transformer,
          converting the low impedance of the main loop (well under 1 ohm) up to
          50 ohms, (the standard input for the radio) which achieves maximum
          power transfer.
          >
          > Reason being i would like to try out Kyle's design of using varactor
          > (tuning) diodes as a tuning capacitor for the main loop...
          >
          > However, if the loop in the schematic is referring to the main loop,
          > then i'm a bit confused at which point in the Pre-amp circuit board
          > do i solder the coupling loop feedline for signal pre-amplification
          > before going out to the receiver.

          No tuning loop is needed with the pre-amp. The output of the
          amplifier (the emitter follower) is set for the maximum power
          transfer to the receiver.
          >
          > best regards,
          >
          > Alan Wong
          >
        • Len Warner
          ... Across a tuned loop if it is a high-input-impedance pre-amp (i.e. a JFET-input amplifier); or in series with the loop and its tuning capacitor (if any) for
          Message 4 of 12 , Jul 7, 2007
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            At 12:49 pm ((PDT)) Fri Jul 6, 2007, dldorrance wrote:
            >[snip]
            >The pre-amp is placed on the main loop.

            Across a tuned loop if it is a high-input-impedance pre-amp
            (i.e. a JFET-input amplifier); or in series with the loop and
            its tuning capacitor (if any) for a very-low-impedance pre-amp;
            otherwise use a matching transformation (not necessarily
            a wound transformer).

            >The main loop (inductor) and
            >capacitor (here a varactor setup) forms a parallel resonant (tuned)
            >circuit.

            So it is very high impedance.

            > In a small loop,

            For an electrically small receiving loop, where the length of the
            conductor is typically one-tenth wavelength or less, the loop will
            consist of a single turn or a small number of turns, except at VLF.

            >the coupling loop is half of a transformer,

            With the main loop forming the primary having a few turns or
            one turn; and the coupling loop forming the secondary with one
            turn or one reduced-area turn.

            So it is an impedance step-down ratio transformer.

            >converting the low impedance of the main loop (well under 1 ohm)

            No - you have said it is parallel-resonant so it is high impedance.
            For a series-resonant loop, the impedance is the radiation
            resistance plus the RF resistance of the loop which basically
            depends on how much copper you can afford to put into it.

            >up to

            No - it's definitely a step-down transformer.

            >50 ohms, (the standard input for the radio)

            That depends on the radio (my HF-150 has 50 ohm,
            600 ohm and high-impedance for a whip) and on the
            feeder you use to connect to it - which may be what
            is to hand rather than what you would have chosen..

            Radio coax is commonly 50 ohms but TV coax is 75 ohms.

            Twin feeder is typically 300, 450 or 600-ish ohms.

            Basically, if you want the matching to be independent of
            frequency and feeder length, you match to the characteristic
            impedance of the feeder and, if necessary, match the feeder
            to the radio at the other end.


            Regards, LenW
            --
            From Yahoo! Groups Help: ... trim all the irrelevant quoted text
            out of your message (as a courtesy to the other members of
            the group to make the digest easier to read).
          • mwwong@qbe.com.my
            Hi Dave, please correct me if i m wrong as i m just a beginner in loop antennas.... in summary, if i were to build a remote tuned loop based on Kyle KOLR
            Message 5 of 12 , Jul 8, 2007
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              Hi Dave,

              please correct me if i'm wrong as i'm just a beginner in loop antennas....

              in summary, if i were to build a remote tuned loop based on Kyle KOLR
              design, the tuning & preamp circuit board will be attached to the main
              loop while i still need another smaller coupling loop (ie. as what
              Portstevos
              has illustrated in his phots) as a feedline into my receiver......

              if this is so, do i need another preamp to be connected to the coupling
              loop?

              as alternative, could i just feed into my receiver from the main loop
              without
              the use of any coupling loop similar to the WL1030 design?....

              please forgive if my above queries sounds a bit silly as i'm still
              grasping around
              on antennas designs....

              best regards,

              Alan Wong






              "dldorrance" <dldorrance@...>
              Sent by: loopantennas@yahoogroups.com
              07/07/2007 03:48 AM
              Please respond to loopantennas

              To: loopantennas@yahoogroups.com
              cc:
              Subject: [loopantennas] Re: Remote_Tuned_Loop By Portstevos


              Hi Alan,

              Please see inline responses.

              Dave WA6YSO

              --- In loopantennas@yahoogroups.com, "alamdamai1" <mwwong@...> wrote:
              >
              > Hi,
              >
              > I'm currently in the process of purchasing parts for fabricating the
              > loop that Portstevos had posted in the Files Section whereby i would
              > like to seek members further knowledge on the original Kyle KOLR
              > Remote-tuned Loop Pre-amp design....
              >
              > May i enquire is the loop as indicated in Kyle's schematic is
              > referring to the main loop or the smaller coupling loop? (pls refer
              > to filename loopdiagram1 for the schematic....)

              The pre-amp is placed on the main loop. The main loop (inductor) and
              capacitor (here a varactor setup) forms a parallel resonant (tuned)
              circuit. In a small loop, the coupling loop is half of a transformer,
              converting the low impedance of the main loop (well under 1 ohm) up to
              50 ohms, (the standard input for the radio) which achieves maximum
              power transfer.
              >
              > Reason being i would like to try out Kyle's design of using varactor
              > (tuning) diodes as a tuning capacitor for the main loop...
              >
              > However, if the loop in the schematic is referring to the main loop,
              > then i'm a bit confused at which point in the Pre-amp circuit board
              > do i solder the coupling loop feedline for signal pre-amplification
              > before going out to the receiver.

              No tuning loop is needed with the pre-amp. The output of the
              amplifier (the emitter follower) is set for the maximum power
              transfer to the receiver.
              >
              > best regards,
              >
              > Alan Wong
              >




              [Non-text portions of this message have been removed]
            • dldorrance
              Hi Alan, You are not the only one who is confused. I am at a disadvantage, as I am not able to read the text which accompanies some of his diagrams (too
              Message 6 of 12 , Jul 9, 2007
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                Hi Alan,

                You are not the only one who is confused.

                I am at a disadvantage, as I am not able to read the text which
                accompanies some of his diagrams (too small). However, looking at the
                two amplifier diagrams, the schematic in Preamp2.jpg is to amplify the
                signal coming out of a traditional small loop antenna, which contains
                a main loop tuned with a traditional variable capacitor and a sense
                loop. The preamplifier simply boosts the signal received by the sense
                loop. It is situated between the sense loop and the transmission line
                coax. It has no tuning function.

                The other preamp, see Looppreamp1.jpg, attaches to the main loop in
                place of the variable capacitor (I think). It contains back-to-back
                varactor diodes, which replace the tuning capacitor and can tune the
                main loop by altering the voltage applied to the varactor diodes.
                With this setup no sense loop is needed.

                Most of the amplified remotely tuned small loops I have seen use a
                preamplifier as in looppreamp1.jpg, which is attached to the main loop
                and works without a sense loop.

                So you need to make some choices. First choice is to build a
                traditional small loop with a variable capacitor and a sense loop.
                There are literally hundreds of websites outlining this method. That
                would give you a feel for how small loops work. Second, you could add
                a preamp between the sense loop and the coax. See the diagram in
                Preamp2.jpg. Third you could build a remotely tuned loop with
                varactor diodes attached to a preamplifier (no need for a sense loop)
                see Looppreamp1.jpg.

                That is a rough outline. The details follow from what you want to
                build. I hope this helps (and I hope I got it right).

                Dave



                --- In loopantennas@yahoogroups.com, mwwong@... wrote:
                >
                > Hi Dave,
                >
                > please correct me if i'm wrong as i'm just a beginner in loop
                antennas....
                >
                > in summary, if i were to build a remote tuned loop based on Kyle KOLR
                > design, the tuning & preamp circuit board will be attached to the main
                > loop while i still need another smaller coupling loop (ie. as what
                > Portstevos
                > has illustrated in his phots) as a feedline into my receiver......
                >
                > if this is so, do i need another preamp to be connected to the coupling
                > loop?
                >
                > as alternative, could i just feed into my receiver from the main loop
                > without
                > the use of any coupling loop similar to the WL1030 design?....
                >
                > please forgive if my above queries sounds a bit silly as i'm still
                > grasping around
                > on antennas designs....
                >
                > best regards,
                >
                > Alan Wong
                >
                >
                >
                >
                >
                >
                > "dldorrance" <dldorrance@...>
                > Sent by: loopantennas@yahoogroups.com
                > 07/07/2007 03:48 AM
                > Please respond to loopantennas
                >
                > To: loopantennas@yahoogroups.com
                > cc:
                > Subject: [loopantennas] Re: Remote_Tuned_Loop By
                Portstevos
                >
                >
                > Hi Alan,
                >
                > Please see inline responses.
                >
                > Dave WA6YSO
                >
                > --- In loopantennas@yahoogroups.com, "alamdamai1" <mwwong@> wrote:
                > >
                > > Hi,
                > >
                > > I'm currently in the process of purchasing parts for fabricating the
                > > loop that Portstevos had posted in the Files Section whereby i would
                > > like to seek members further knowledge on the original Kyle KOLR
                > > Remote-tuned Loop Pre-amp design....
                > >
                > > May i enquire is the loop as indicated in Kyle's schematic is
                > > referring to the main loop or the smaller coupling loop? (pls refer
                > > to filename loopdiagram1 for the schematic....)
                >
                > The pre-amp is placed on the main loop. The main loop (inductor) and
                > capacitor (here a varactor setup) forms a parallel resonant (tuned)
                > circuit. In a small loop, the coupling loop is half of a transformer,
                > converting the low impedance of the main loop (well under 1 ohm) up to
                > 50 ohms, (the standard input for the radio) which achieves maximum
                > power transfer.
                > >
                > > Reason being i would like to try out Kyle's design of using varactor
                > > (tuning) diodes as a tuning capacitor for the main loop...
                > >
                > > However, if the loop in the schematic is referring to the main loop,
                > > then i'm a bit confused at which point in the Pre-amp circuit board
                > > do i solder the coupling loop feedline for signal pre-amplification
                > > before going out to the receiver.
                >
                > No tuning loop is needed with the pre-amp. The output of the
                > amplifier (the emitter follower) is set for the maximum power
                > transfer to the receiver.
                > >
                > > best regards,
                > >
                > > Alan Wong
                > >
                >
                >
                >
                >
                > [Non-text portions of this message have been removed]
                >
              • aimo ruoho
                Would this new system be as good or even better than the very costly (excessively expencive) Badbrook antennas? If so, I for 1 would be very much interested to
                Message 7 of 12 , Jul 10, 2007
                • 0 Attachment
                  Would this new system be as good or even better than the very costly (excessively expencive) Badbrook antennas?
                  If so, I for 1 would be very much interested to build 1 or more of them!
                  Aimo

                  dldorrance <dldorrance@...> wrote:
                  Hi Alan,

                  You are not the only one who is confused.

                  I am at a disadvantage, as I am not able to read the text which
                  accompanies some of his diagrams (too small). However, looking at the
                  two amplifier diagrams, the schematic in Preamp2.jpg is to amplify the
                  signal coming out of a traditional small loop antenna, which contains
                  a main loop tuned with a traditional variable capacitor and a sense
                  loop. The preamplifier simply boosts the signal received by the sense
                  loop. It is situated between the sense loop and the transmission line
                  coax. It has no tuning function.

                  The other preamp, see Looppreamp1.jpg, attaches to the main loop in
                  place of the variable capacitor (I think). It contains back-to-back
                  varactor diodes, which replace the tuning capacitor and can tune the
                  main loop by altering the voltage applied to the varactor diodes.
                  With this setup no sense loop is needed.

                  Most of the amplified remotely tuned small loops I have seen use a
                  preamplifier as in looppreamp1.jpg, which is attached to the main loop
                  and works without a sense loop.

                  So you need to make some choices. First choice is to build a
                  traditional small loop with a variable capacitor and a sense loop.
                  There are literally hundreds of websites outlining this method. That
                  would give you a feel for how small loops work. Second, you could add
                  a preamp between the sense loop and the coax. See the diagram in
                  Preamp2.jpg. Third you could build a remotely tuned loop with
                  varactor diodes attached to a preamplifier (no need for a sense loop)
                  see Looppreamp1.jpg.

                  That is a rough outline. The details follow from what you want to
                  build. I hope this helps (and I hope I got it right).

                  Dave

                  --- In loopantennas@yahoogroups.com, mwwong@... wrote:
                  >
                  > Hi Dave,
                  >
                  > please correct me if i'm wrong as i'm just a beginner in loop
                  antennas....
                  >
                  > in summary, if i were to build a remote tuned loop based on Kyle KOLR
                  > design, the tuning & preamp circuit board will be attached to the main
                  > loop while i still need another smaller coupling loop (ie. as what
                  > Portstevos
                  > has illustrated in his phots) as a feedline into my receiver......
                  >
                  > if this is so, do i need another preamp to be connected to the coupling
                  > loop?
                  >
                  > as alternative, could i just feed into my receiver from the main loop
                  > without
                  > the use of any coupling loop similar to the WL1030 design?....
                  >
                  > please forgive if my above queries sounds a bit silly as i'm still
                  > grasping around
                  > on antennas designs....
                  >
                  > best regards,
                  >
                  > Alan Wong
                  >
                  >
                  >
                  >
                  >
                  >
                  > "dldorrance" <dldorrance@...>
                  > Sent by: loopantennas@yahoogroups.com
                  > 07/07/2007 03:48 AM
                  > Please respond to loopantennas
                  >
                  > To: loopantennas@yahoogroups.com
                  > cc:
                  > Subject: [loopantennas] Re: Remote_Tuned_Loop By
                  Portstevos
                  >
                  >
                  > Hi Alan,
                  >
                  > Please see inline responses.
                  >
                  > Dave WA6YSO
                  >
                  > --- In loopantennas@yahoogroups.com, "alamdamai1" <mwwong@> wrote:
                  > >
                  > > Hi,
                  > >
                  > > I'm currently in the process of purchasing parts for fabricating the
                  > > loop that Portstevos had posted in the Files Section whereby i would
                  > > like to seek members further knowledge on the original Kyle KOLR
                  > > Remote-tuned Loop Pre-amp design....
                  > >
                  > > May i enquire is the loop as indicated in Kyle's schematic is
                  > > referring to the main loop or the smaller coupling loop? (pls refer
                  > > to filename loopdiagram1 for the schematic....)
                  >
                  > The pre-amp is placed on the main loop. The main loop (inductor) and
                  > capacitor (here a varactor setup) forms a parallel resonant (tuned)
                  > circuit. In a small loop, the coupling loop is half of a transformer,
                  > converting the low impedance of the main loop (well under 1 ohm) up to
                  > 50 ohms, (the standard input for the radio) which achieves maximum
                  > power transfer.
                  > >
                  > > Reason being i would like to try out Kyle's design of using varactor
                  > > (tuning) diodes as a tuning capacitor for the main loop...
                  > >
                  > > However, if the loop in the schematic is referring to the main loop,
                  > > then i'm a bit confused at which point in the Pre-amp circuit board
                  > > do i solder the coupling loop feedline for signal pre-amplification
                  > > before going out to the receiver.
                  >
                  > No tuning loop is needed with the pre-amp. The output of the
                  > amplifier (the emitter follower) is set for the maximum power
                  > transfer to the receiver.
                  > >
                  > > best regards,
                  > >
                  > > Alan Wong
                  > >
                  >
                  >
                  >
                  >
                  > [Non-text portions of this message have been removed]
                  >






                  ---------------------------------
                  We won't tell. Get more on shows you hate to love
                  (and love to hate): Yahoo! TV's Guilty Pleasures list.

                  [Non-text portions of this message have been removed]
                • jr_dakota
                  In the files section there is a file called Loop Circuit.rtf .... The left schematic is what I used, I used a single varactor simply because the signal levels
                  Message 8 of 12 , Jul 10, 2007
                  • 0 Attachment
                    In the files section there is a file called Loop Circuit.rtf .... The
                    left schematic is what I used, I used a single varactor simply because
                    the signal levels are so small that it's really not necessary to do
                    the series/parallel thing with 4 of them (But you DO need them that
                    way to tune a whip or 'longwire' which will have voltage spikes from
                    noise not present in the magnetic field loop)

                    I don't use that preamp anymore but opted for a lower noise, higher
                    gain, more gain range low impedance RF amp shown in file
                    Lo_Imp_Loop_Preamp

                    The main drawback to my system (well for most people) is that you need
                    to run seperate wires for controlling the tuning, amp gain, and to
                    supply power but IMO this is the best way to go, feeding a coax so the
                    RF has to ride a DC voltage is almost always noisier than seperate
                    feeds for the DC voltages

                    My loop is made from a piece of 1/2" O.D. (Yes O.D. it's refrigeration
                    copper I get for free) soft copper tubing 10 foot long and mounted on
                    my roof with a cheap Channel Master rotor and I use a coax shielded
                    (balanced) pickup loop .... It'll be 3 years in September since I
                    mounted it and other than changing the preamp to the new style, it's
                    never been touched or had a problem ... The preamp has enough gain
                    that I can pickup up a lot of AM BCB stations even though the loop
                    itself only tunes down to ~5 Mhz ...

                    I'm interested to see what my bulletproof RF amplified untuned loop (
                    a Sickbrook clone with MY OWN ORIGINAL CIRCUITRY)) will compare to it

                    JR



                    --- In loopantennas@yahoogroups.com, mwwong@... wrote:
                    >
                    > Howday Mate.....
                    >
                    > thanks Michael for sharing with us on what you went through....
                    >
                    > well, my MVAM108 has yet to arrive from the States and once i've
                    > assemble the board, will definately post it in this Group on its
                    > outcome....
                    >
                    > Alan Wong.
                  • jr_dakota
                    The ONLY real advantage a Wellbrook (or any other amplifiied untuned loop) has over a tuned loop is a wide range of operating frequencies and a tuned loop has
                    Message 9 of 12 , Jul 10, 2007
                    • 0 Attachment
                      The ONLY real advantage a Wellbrook (or any other amplifiied untuned
                      loop) has over a tuned loop is a wide range of operating frequencies
                      and a tuned loop has several advantages over an untuned loop as long
                      as you stay in the frequency range the loop is designed for, for
                      instance a tuned loop has some filtering capabilities not present in
                      any untuned loop, it also tends to have a more stable output impedence
                      making the preamp design easier to do effectively or not even having
                      to use a preamp in some cases

                      The down side is to tune from LF up to the upper end of the HF range
                      you need several tuned loops whereas one untuned loop will do the same
                      job **if** you have a well designed wideband RF preamp/impedance
                      converter to go with it

                      I'm working on an untuned amplified loop with a high IP2/IP3 preamp
                      but I don't get much done in the shop during the summer months and I
                      didn't get my antenna analyzer (AmQRP Antenna Analyst "AA-908"),
                      spectrum analyzer (KangaUS kit of Wes Hayward's design) and misc. gear
                      for IP2/IP3 testing done until late spring


                      --- In loopantennas@yahoogroups.com, aimo ruoho <aimounto@...> wrote:
                      >
                      > Would this new system be as good or even better than the very costly
                      (excessively expencive) Badbrook antennas?
                      > If so, I for 1 would be very much interested to build 1 or more of
                      them!
                      > Aimo
                      >
                      > dldorrance <dldorrance@...> wrote:
                      > Hi Alan,
                    • mwwong@qbe.com.my
                      Hi JR, Hmmm.....if i knew earlier the Kyle KOLR design would have a higher noise floor, i would opt for your Pre-amp design which i choose not to earlier as i
                      Message 10 of 12 , Jul 10, 2007
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                        Hi JR,

                        Hmmm.....if i knew earlier the Kyle KOLR design would have a higher
                        noise floor, i would opt for your Pre-amp design which i choose not to
                        earlier as i thought Kyle's circuit looks more 'sophisticated'.....

                        nevertheless, i will also try out your Pre-amp and see what happens.....

                        oh...great, now i've to order a toroid for the transformer.....

                        best regards,

                        Alan Wong.




                        "jr_dakota" <SG2112@...>
                        Sent by: loopantennas@yahoogroups.com
                        07/11/2007 08:04 AM
                        Please respond to loopantennas

                        To: loopantennas@yahoogroups.com
                        cc:
                        Subject: [loopantennas] Re: Remote_Tuned_Loop By Portstevos


                        In the files section there is a file called Loop Circuit.rtf .... The
                        left schematic is what I used, I used a single varactor simply because
                        the signal levels are so small that it's really not necessary to do
                        the series/parallel thing with 4 of them (But you DO need them that
                        way to tune a whip or 'longwire' which will have voltage spikes from
                        noise not present in the magnetic field loop)

                        I don't use that preamp anymore but opted for a lower noise, higher
                        gain, more gain range low impedance RF amp shown in file
                        Lo_Imp_Loop_Preamp

                        The main drawback to my system (well for most people) is that you need
                        to run seperate wires for controlling the tuning, amp gain, and to
                        supply power but IMO this is the best way to go, feeding a coax so the
                        RF has to ride a DC voltage is almost always noisier than seperate
                        feeds for the DC voltages

                        My loop is made from a piece of 1/2" O.D. (Yes O.D. it's refrigeration
                        copper I get for free) soft copper tubing 10 foot long and mounted on
                        my roof with a cheap Channel Master rotor and I use a coax shielded
                        (balanced) pickup loop .... It'll be 3 years in September since I
                        mounted it and other than changing the preamp to the new style, it's
                        never been touched or had a problem ... The preamp has enough gain
                        that I can pickup up a lot of AM BCB stations even though the loop
                        itself only tunes down to ~5 Mhz ...

                        I'm interested to see what my bulletproof RF amplified untuned loop (
                        a Sickbrook clone with MY OWN ORIGINAL CIRCUITRY)) will compare to it

                        JR

                        --- In loopantennas@yahoogroups.com, mwwong@... wrote:
                        >
                        > Howday Mate.....
                        >
                        > thanks Michael for sharing with us on what you went through....
                        >
                        > well, my MVAM108 has yet to arrive from the States and once i've
                        > assemble the board, will definately post it in this Group on its
                        > outcome....
                        >
                        > Alan Wong.




                        [Non-text portions of this message have been removed]
                      • jr_dakota
                        You ll also need a PIN Diode too (MPN3404 or equiv.) although a 1N4007 will work with just a tad more intermod distortion from what I ve heard .... You can
                        Message 11 of 12 , Jul 11, 2007
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                          You'll also need a PIN Diode too (MPN3404 or equiv.) although a 1N4007
                          will work with just a tad more intermod distortion from what I've
                          heard .... You can also use a different transistor, a 2N2222 or a
                          2N3904 will work too with a slight (perhaps even imperceptible)
                          increase in Noise Figure

                          You could also set it up with a fixed gain ... If you put the end of
                          C1 to ground and get rid of everything to the left you'd have a fixed
                          gain of about 30db .... you could change the value of R5 to lower the
                          gain or you could remove the grounded end of C1 and put some
                          resistance between it and ground to partially bypass the emitter which
                          is essentially what the PIN diode does ... a 1K ohm Trimmer would
                          probably be the best solution, then you could set it for the gain you
                          want 'by ear' if you don't have the test equipment and then leave it

                          Other than changing the input biasing to 'long tailed biasing' to get
                          the input impedance down to 50 ohms, the rest of the circuit is Wes
                          Hayward's from the book Experimental Methods in RF Design and found in
                          the IF section .... I wanted to be able to control the gain remotely
                          and IF amps are a good place to start for circuits like that ... this
                          particular one doesn't increase in noise when you reduce the gain like
                          most do which made it more adaptable for a front end preamp

                          FETs are great in higher impedance circuits and although you see a lot
                          of 50 ohm FET RF Preamps, I've never been able to get the performance
                          or stabilty I've wanted using them in 50 low impedance circuits ...
                          The previous preamp worked, it was quiet but I never could get enough
                          gain out of it when I needed more than normal, for instance using the
                          antenna outside it's tuning range .... at 50 ohms about all I could
                          get out of it without raising the input impedance was 10-12 db (Which
                          is enough for most antennas but not quite enough for Loops in my
                          experience)

                          JR

                          --- In loopantennas@yahoogroups.com, mwwong@... wrote:
                          >
                          > Hi JR,
                          >
                          > Hmmm.....if i knew earlier the Kyle KOLR design would have a higher
                          > noise floor, i would opt for your Pre-amp design which i choose not to
                          > earlier as i thought Kyle's circuit looks more 'sophisticated'.....
                          >
                          > nevertheless, i will also try out your Pre-amp and see what happens.....
                          >
                          > oh...great, now i've to order a toroid for the transformer.....
                          >
                          > best regards,
                          >
                          > Alan Wong.
                          >
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