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Antenna amplifier link

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  • John Popelish
    I just added a link to a PDF that gives design info for an ultralinear, common base, transformer feedback antenna amplifiers. Link name: Ultralinear 2N5109 And
    Message 1 of 16 , Apr 22 1:28 PM
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      I just added a link to a PDF that gives design info for an
      ultralinear, common base, transformer feedback antenna amplifiers.
      Link name:
      Ultralinear 2N5109 And 2N3053 Amplifiers

      I haven't studied it yet, but just breowsing through, I thought
      someone here might use it.
    • Steve Ratzlaff
      Hi, I missed seeing the link in your message, but if the article is by Dallas Lankford (who has an article with that precise name), then it s very excellent.
      Message 2 of 16 , Apr 22 1:43 PM
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        Hi,
        I missed seeing the link in your message, but if the article is by Dallas Lankford (who has an article with that precise name), then it's very excellent. I've built and used preamps from that article for a number of years now. I highly recommend the Dallas Lankford article.
        His articles can be found at http://www.kongsfjord.no/. Click on "The Dallas Files".
        Steve
        ----- Original Message -----
        From: John Popelish
        To: loopantennas@yahoogroups.com
        Sent: Saturday, April 22, 2006 1:28 PM
        Subject: [loopantennas] Antenna amplifier link


        I just added a link to a PDF that gives design info for an
        ultralinear, common base, transformer feedback antenna amplifiers.
        Link name:
        Ultralinear 2N5109 And 2N3053 Amplifiers

        I haven't studied it yet, but just breowsing through, I thought
        someone here might use it.





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      • John Popelish
        ... I didn t include the link, itself, only the title in my message, but it is one of the Dallas files.
        Message 3 of 16 , Apr 22 4:48 PM
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          Steve Ratzlaff wrote:
          > Hi,
          > I missed seeing the link in your message, but if the article is by Dallas Lankford (who has an article with that precise name), then it's very excellent. I've built and used preamps from that article for a number of years now. I highly recommend the Dallas Lankford article.
          > His articles can be found at http://www.kongsfjord.no/. Click on "The Dallas Files".

          I didn't include the link, itself, only the title in my message, but
          it is one of the Dallas files.
        • jland138
          Steve, I joined the LWCA a few months ago and noticed that several contributors to the DX Downstairs column list an active whip preamp built by you in their
          Message 4 of 16 , Apr 22 6:55 PM
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            Steve,

            I joined the LWCA a few months ago and noticed that several
            contributors to the "DX Downstairs" column list an active whip
            preamp built by you in their equipment summary. Are you using a
            2N5109 in your design? Or, is it based on the AMRAD antenna?

            Thanks,

            Joe

            --- In loopantennas@yahoogroups.com, "Steve Ratzlaff" <steveratz@...>
            wrote:
            >
            > Hi,
            > I missed seeing the link in your message, but if the article is by
            > Dallas Lankford (who has an article with that precise name), then
            > it's very excellent. I've built and used preamps from that article
            > for a number of years now. I highly recommend the Dallas Lankford
            > article. His articles can be found at http://www.kongsfjord.no/.
            > Click on "The Dallas Files".
            > Steve
          • jr_dakota
            I use one with 2SC1253 s in my SDR testbed , it was about the only thing I could find with a higher IP3 than the Tayloe Detector that follows it ... you need a
            Message 5 of 16 , Apr 23 1:10 AM
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              I use one with 2SC1253's in my SDR testbed , it was about the only
              thing I could find with a higher IP3 than the Tayloe Detector that
              follows it ... you need a preamp with a very high IP3 in order to not
              degrade the Tayloe Detector's IP3 ... plus you get inherent 2nd
              harmonic rejection with push-pull which is a big plus with direct
              conversion receiver

              Over the summer I plan on using one with an untuned 4 foot diameter
              loop similar to the Wellbrook, the only real problem I have yet to
              solve is how I need to couple the loop to the preamp ... obviously a
              wideband transformer of sorts is called for, I just need to work out
              needed gain, impedances, and tweak the details in the prototype

              JR

              --- In loopantennas@yahoogroups.com, "John Popelish" <jpopelish@...>
              wrote:
              >
              > I just added a link to a PDF that gives design info for an
              > ultralinear, common base, transformer feedback antenna amplifiers.
              > Link name:
              > Ultralinear 2N5109 And 2N3053 Amplifiers
              >
              > I haven't studied it yet, but just breowsing through, I thought
              > someone here might use it.
              >
            • Steve Ratzlaff
              Hi Joe, The active whip I build uses my own design, unrelated to the AMRAD circuit which Ralph Burhans originally designed in the 1980 s and which Dallas
              Message 6 of 16 , Apr 23 8:56 AM
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                Hi Joe,
                The active whip I build uses my own design, unrelated to the AMRAD circuit which Ralph Burhans originally designed in the 1980's and which Dallas Lankford optimized with the Crystallonics powerfet and that AMRAD received permission to use for their article.
                My active whip is mainly used by LF DXers, though it's very broadband; and has good strong-signal performance. The circuit is proprietary, though if you buy one I can provide the schematic if asked to.
                I hope you have good results with your own LF reception. DXing LF beacons has been an interest of mine since the 1980's.
                Steve AA7U
                ----- Original Message -----
                From: jland138
                To: loopantennas@yahoogroups.com
                Sent: Saturday, April 22, 2006 6:55 PM
                Subject: [loopantennas] Re: Antenna amplifier link


                Steve,

                I joined the LWCA a few months ago and noticed that several
                contributors to the "DX Downstairs" column list an active whip
                preamp built by you in their equipment summary. Are you using a
                2N5109 in your design? Or, is it based on the AMRAD antenna?

                Thanks,

                Joe

                --- In loopantennas@yahoogroups.com, "Steve Ratzlaff" <steveratz@...>
                wrote:
                >
                > Hi,
                > I missed seeing the link in your message, but if the article is by
                > Dallas Lankford (who has an article with that precise name), then
                > it's very excellent. I've built and used preamps from that article
                > for a number of years now. I highly recommend the Dallas Lankford
                > article. His articles can be found at http://www.kongsfjord.no/.
                > Click on "The Dallas Files".
                > Steve








                If you've got links, post them in the Links section!
                http://groups.yahoo.com/group/loopantennas/links

                Post files here. If the file comes from a website, please put it in the Links rather than uploading the file.
                http://groups.yahoo.com/group/loopantennas/files

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                And please trim all this when replying!



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                [Non-text portions of this message have been removed]
              • jland138
                Steve, Thanks, I d certainly be interested in getting hold of one of yours. I started out on LF with an LF Engineering L-400B, which I wasn t very happy with.
                Message 7 of 16 , Apr 23 11:16 PM
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                  Steve,

                  Thanks, I'd certainly be interested in getting hold of one of yours.
                  I started out on LF with an LF Engineering L-400B, which I wasn't
                  very happy with. Built a few loops based on VE7SL's Burhans preamp
                  using a U310 followed by a 2N3904, mainly for sync'ing some equipment
                  with WWVB and they work pretty well. I built a pair of AMRAD active
                  antennas which are good on LF, but I probably don't have them mounted
                  high enough and in the clear to get them to their full capability.
                  Found a bunch of 2N5109's for the Norton CBTF amps that the Lankford
                  article describes, but haven't had a chance to build one for LF yet.

                  Joe

                  --- In loopantennas@yahoogroups.com, "Steve Ratzlaff" <steveratz@...>
                  wrote:
                  >
                  > Hi Joe,
                  > The active whip I build uses my own design, unrelated to the AMRAD
                  > circuit which Ralph Burhans originally designed in the 1980's and
                  > which Dallas Lankford optimized with the Crystallonics powerfet and
                  > that AMRAD received permission to use for their article.
                  > My active whip is mainly used by LF DXers, though it's very broadband;
                  > and has good strong-signal performance. The circuit is proprietary,
                  > though if you buy one I can provide the schematic if asked to.
                  > I hope you have good results with your own LF reception. DXing LF
                  > beacons has been an interest of mine since the 1980's.
                  > Steve AA7U
                • Paul Birke
                  Found a bunch of 2N5109 s for the Norton CBTF amps that the Lankford article describes, but haven t had a chance to build one for LF yet. hi Joe et al Has
                  Message 8 of 16 , Apr 24 7:56 AM
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                    Found a bunch of 2N5109's for the Norton CBTF amps
                    that the Lankford
                    article describes, but haven't had a chance to build
                    one for LF yet.

                    hi Joe et al


                    Has anyone in the group built and tried out these
                    amps?

                    Paul
                  • John Popelish
                    ... (snip) I suspect that using a transistor like this, with gain to well over a gigahertz, is likely to cause oscillation problems in an LF amplifier. You
                    Message 9 of 16 , Apr 25 7:38 AM
                    • 0 Attachment
                      --- In loopantennas@yahoogroups.com, Paul Birke <nonlinear@...> wrote:
                      >
                      > Found a bunch of 2N5109's for the Norton CBTF amps
                      > that the Lankford
                      > article describes, but haven't had a chance to build
                      > one for LF yet.
                      (snip)

                      I suspect that using a transistor like this, with gain to well over a
                      gigahertz, is likely to cause oscillation problems in an LF amplifier.
                      You should be able to use much slower, low noise, high gain types,
                      like 2N5088/9.
                    • Paul Birke
                      ... build ... (snip) I suspect that using a transistor like this, with gain to well over a gigahertz, is likely to cause oscillation problems in an LF
                      Message 10 of 16 , Apr 25 7:54 AM
                      • 0 Attachment
                        --- John Popelish <jpopelish@...> wrote:


                        ---------------------------------
                        --- In loopantennas@yahoogroups.com, Paul Birke
                        <nonlinear@...> wrote:
                        >
                        > Found a bunch of 2N5109's for the Norton CBTF amps
                        > that the Lankford
                        > article describes, but haven't had a chance to
                        build
                        > one for LF yet.
                        (snip)

                        I suspect that using a transistor like this, with gain
                        to well over a
                        gigahertz, is likely to cause oscillation problems in
                        an LF amplifier.
                        You should be able to use much slower, low noise,
                        high gain types,
                        like 2N5088/9.

                        **************

                        Dear John

                        I am going to thank you for this and file for now

                        one day I will try to build two of these babies
                        and we the transistors you mention above.
                        these are very good points you make about oscillations
                        and low noise.

                        thanks

                        Paul
                      • gandalfg8@aol.com
                        In a message dated 25/04/2006 15:41:23 GMT Daylight Time, jpopelish@rica.net writes: I suspect that using a transistor like this, with gain to well over a
                        Message 11 of 16 , Apr 25 8:37 AM
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                          In a message dated 25/04/2006 15:41:23 GMT Daylight Time, jpopelish@...
                          writes:

                          I suspect that using a transistor like this, with gain to well over a
                          gigahertz, is likely to cause oscillation problems in an LF amplifier.
                          You should be able to use much slower, low noise, high gain types,
                          like 2N5088/9.



                          Generally speaking the higher frequency response doesn't cause a problem.
                          If it does it can usually be tamed with ferrite beads.
                          The 2N5109 is an excellent example of the type of medium power transistor,
                          usually TO5 or TO39, often used in vertical whip active antennas following
                          the input FET.
                          As with similar devices such as the 2N3866 and 2N3553 it can be driven quite
                          hard to maintain good linearity whilst providing a relatively low impedance
                          output.

                          The biggest problem I've found with this type of antenna is that they can
                          often easily overload the receiver and cause significant intermodulation
                          products.
                          This is something worth remembering when considering the fancy specs
                          sometimes quoted for active antennas.
                          A high IP3 for the antenna is one thing, but hitting the radio with a level
                          of signal it can't cope with wipes out any advantage.
                          Switched or tuned bandpass filters coupled with an input attenuator can
                          often make for a great improvement.

                          In terms of filtering, of course, this is an area where the tuned loop has
                          the advantage to start with:-)

                          regards

                          Nigel
                          G8PZR


                          [Non-text portions of this message have been removed]
                        • jr_dakota
                          Yes, I m using one in a SDR front end and have another partially built for a Wellbrook loop clone I m working on .... They are so bullet proof you could put a
                          Message 12 of 16 , Apr 25 2:01 PM
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                            Yes, I'm using one in a SDR front end and have another partially built
                            for a Wellbrook loop clone I'm working on .... They are so bullet
                            proof you could put a full watt of power into them and they'll hardly
                            burp .... the inherent 2nd harmonic cancellation (just like a push
                            pull audio power amps) makes them especially attractive in Direct
                            Conversion designs where IP2 is more important than IP3 ... it's also
                            an excellent match to the Tayloe/QSD detector which has an
                            outrageously high IP3 for a mixer so you need a preamp with an
                            outrageously high IP3 so as not to degrade performance ... this baby
                            is it .... there is also a similar design by Jacob Makhinson, N6NWP
                            but it uses a bipolar supply for biasing and grounded bases by the
                            slight performance increase isn't worth the hassle in my opinion ...
                            then again I usually have a bipolar supply in most of my designs for
                            audio frequency circuits (a bipolar supply opamp will beat a single
                            supply in noise and power supply rejection every time) so then it
                            wouldn't be a big deal

                            JR

                            --- In loopantennas@yahoogroups.com, Paul Birke <nonlinear@...> wrote:
                            >
                            >
                            >
                            >
                            > Found a bunch of 2N5109's for the Norton CBTF amps
                            > that the Lankford
                            > article describes, but haven't had a chance to build
                            > one for LF yet.
                            >
                            > hi Joe et al
                            >
                            >
                            > Has anyone in the group built and tried out these
                            > amps?
                            >
                            > Paul
                            >
                          • jr_dakota
                            Between the bead on the collector and the inherent way the Norton topology works, VHF oscillation is not a problem in my experience ... in fact the only Norton
                            Message 13 of 16 , Apr 25 2:07 PM
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                              Between the bead on the collector and the inherent way the Norton
                              topology works, VHF oscillation is not a problem in my experience ...
                              in fact the only Norton amp (And I've used them single ended for a few
                              years) that ever 'went off' on me was when I screwed up and got the
                              phasing wrong on the transformer .... made a helluva a VHF transmitter
                              though ;-)

                              JR

                              --- In loopantennas@yahoogroups.com, "John Popelish" <jpopelish@...>
                              wrote:
                              >
                              > --- In loopantennas@yahoogroups.com, Paul Birke <nonlinear@> wrote:
                              > >
                              > > Found a bunch of 2N5109's for the Norton CBTF amps
                              > > that the Lankford
                              > > article describes, but haven't had a chance to build
                              > > one for LF yet.
                              > (snip)
                              >
                              > I suspect that using a transistor like this, with gain to well over a
                              > gigahertz, is likely to cause oscillation problems in an LF amplifier.
                              > You should be able to use much slower, low noise, high gain types,
                              > like 2N5088/9.
                              >
                            • Paul Birke
                              very good JR thanks Paul any enhancements on Dallas orginal article? any further hints? Dan s Part for the transistors I guess. Paul ... Yes, I m using one in
                              Message 14 of 16 , Apr 25 8:05 PM
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                                very good JR

                                thanks

                                Paul

                                any enhancements on Dallas' orginal article?
                                any further hints?
                                Dan's Part for the transistors I guess.

                                Paul


                                --- jr_dakota <SG2112@...> wrote:


                                ---------------------------------
                                Yes, I'm using one in a SDR front end and have another
                                partially built
                                for a Wellbrook loop clone I'm working on .... They
                                are so bullet
                                proof you could put a full watt of power into them and
                                they'll hardly
                                burp .... the inherent 2nd harmonic cancellation (just
                                like a push
                                pull audio power amps) makes them especially
                                attractive in Direct
                                Conversion designs where IP2 is more important than
                                IP3 ... it's also
                                an excellent match to the Tayloe/QSD detector which
                                has an
                                outrageously high IP3 for a mixer so you need a preamp
                                with an
                                outrageously high IP3 so as not to degrade performance
                                ... this baby
                                is it .... there is also a similar design by Jacob
                                Makhinson, N6NWP
                                but it uses a bipolar supply for biasing and grounded
                                bases by the
                                slight performance increase isn't worth the hassle in
                                my opinion ...
                                then again I usually have a bipolar supply in most of
                                my designs for
                                audio frequency circuits (a bipolar supply opamp will
                                beat a single
                                supply in noise and power supply rejection every time)
                                so then it
                                wouldn't be a big deal

                                JR

                                --- In loopantennas@yahoogroups.com, Paul Birke
                                <nonlinear@...> wrote:
                                >
                                >
                                >
                                >
                                > Found a bunch of 2N5109's for the Norton CBTF amps
                                > that the Lankford
                                > article describes, but haven't had a chance to
                                build
                                > one for LF yet.
                                >
                                > hi Joe et al
                                >
                                >
                                > Has anyone in the group built and tried out these
                                > amps?
                                >
                                > Paul
                                >






                                If you've got links, post them in the Links section!
                                http://groups.yahoo.com/group/loopantennas/links

                                Post files here. If the file comes from a website,
                                please put it in the Links rather than uploading the
                                file.
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                                Photos. Upload JPG and GIF into Photos. Please convert
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                                ---------------------------------
                              • jr_dakota
                                A couple of tips Keep the layout symetrical as possible Match your resistors within .1% and you don t need the ten turn trim pot (You ll still use a fixed
                                Message 15 of 16 , Apr 28 10:33 PM
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                                  A couple of tips

                                  Keep the layout symetrical as possible

                                  Match your resistors within .1% and you don't need the ten turn trim
                                  pot (You'll still use a fixed resistor there) unless you are really picky

                                  If your primary interest is above 2Mhz use a #43 cores, if it's below
                                  2Mhz use a #75 or a 'J' cores

                                  Pay real close attention to phasing of all the transformers, one out
                                  of whack with throw the whole circuit off, possibly to the point of
                                  making it a relatively high powered VHF oscillator

                                  I also use a slightly different biasing scheme, I use different
                                  resistors at the base to set my current and keep a fixed 51 ohm
                                  resistor on the input/emitter to get a better 50 ohm input/output
                                  impedance match ... basically my biasing values are the same as this
                                  in my SDR http://www.qrp.pops.net/preamp.htm (bottom of page)

                                  Unless you need a balanced circuit (an untuned loop for example)
                                  and/or have a REALLY strong mixer (A +17 DBM or a Tayloe Detector)
                                  following it, you'd probably be as well or better off with a single
                                  transistor Norton amp ... it's also an advantage to use the push-pull
                                  setup for Direct Conversion because of the inherent 2nd harmonic
                                  cancellation

                                  JR

                                  --- In loopantennas@yahoogroups.com, Paul Birke <nonlinear@...> wrote:
                                  >
                                  > very good JR
                                  >
                                  > thanks
                                  >
                                  > Paul
                                  >
                                  > any enhancements on Dallas' orginal article?
                                  > any further hints?
                                  > Dan's Part for the transistors I guess.
                                  >
                                  > Paul
                                  >
                                  >
                                  > --- jr_dakota <SG2112@...> wrote:
                                  >
                                  >
                                  > ---------------------------------
                                  > Yes, I'm using one in a SDR front end and have another
                                  > partially built
                                  > for a Wellbrook loop clone I'm working on .... They
                                  > are so bullet
                                  > proof you could put a full watt of power into them and
                                  > they'll hardly
                                  > burp .... the inherent 2nd harmonic cancellation (just
                                  > like a push
                                  > pull audio power amps) makes them especially
                                  > attractive in Direct
                                  > Conversion designs where IP2 is more important than
                                  > IP3 ... it's also
                                  > an excellent match to the Tayloe/QSD detector which
                                  > has an
                                  > outrageously high IP3 for a mixer so you need a preamp
                                  > with an
                                  > outrageously high IP3 so as not to degrade performance
                                  > ... this baby
                                  > is it .... there is also a similar design by Jacob
                                  > Makhinson, N6NWP
                                  > but it uses a bipolar supply for biasing and grounded
                                  > bases by the
                                  > slight performance increase isn't worth the hassle in
                                  > my opinion ...
                                  > then again I usually have a bipolar supply in most of
                                  > my designs for
                                  > audio frequency circuits (a bipolar supply opamp will
                                  > beat a single
                                  > supply in noise and power supply rejection every time)
                                  > so then it
                                  > wouldn't be a big deal
                                  >
                                  > JR
                                  >
                                  > --- In loopantennas@yahoogroups.com, Paul Birke
                                  > <nonlinear@> wrote:
                                  > >
                                  > >
                                  > >
                                  > >
                                  > > Found a bunch of 2N5109's for the Norton CBTF amps
                                  > > that the Lankford
                                  > > article describes, but haven't had a chance to
                                  > build
                                  > > one for LF yet.
                                  > >
                                  > > hi Joe et al
                                  > >
                                  > >
                                  > > Has anyone in the group built and tried out these
                                  > > amps?
                                  > >
                                  > > Paul
                                  > >
                                  >
                                  >
                                  >
                                  >
                                  >
                                  >
                                  > If you've got links, post them in the Links section!
                                  > http://groups.yahoo.com/group/loopantennas/links
                                  >
                                  > Post files here. If the file comes from a website,
                                  > please put it in the Links rather than uploading the
                                  > file.
                                  > http://groups.yahoo.com/group/loopantennas/files
                                  >
                                  > You can now view images at higher resolution in
                                  > Photos. Upload JPG and GIF into Photos. Please convert
                                  > BMP or TIF to JPG or GIF before uploading.
                                  > http://ph.groups.yahoo.com/group/loopantennas/photos
                                  >
                                  > And please trim all this when replying!
                                  >
                                  >
                                  >
                                  > ---------------------------------
                                  > YAHOO! GROUPS LINKS
                                  >
                                  >
                                  > Visit your group "loopantennas" on the web.
                                  >
                                  > To unsubscribe from this group, send an email to:
                                  > loopantennas-unsubscribe@yahoogroups.com
                                  >
                                  > Your use of Yahoo! Groups is subject to the Yahoo!
                                  > Terms of Service.
                                  >
                                  >
                                  > ---------------------------------
                                  >
                                • Paul Birke
                                  thanks so much JR for this Paul ... A couple of tips Keep the layout symetrical as possible Match your resistors within .1% and you don t need the ten turn
                                  Message 16 of 16 , Apr 29 8:10 AM
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                                    thanks so much JR for this

                                    Paul

                                    --- jr_dakota <SG2112@...> wrote:


                                    ---------------------------------
                                    A couple of tips

                                    Keep the layout symetrical as possible

                                    Match your resistors within .1% and you don't need the
                                    ten turn trim
                                    pot (You'll still use a fixed resistor there) unless
                                    you are really picky

                                    If your primary interest is above 2Mhz use a #43
                                    cores, if it's below
                                    2Mhz use a #75 or a 'J' cores

                                    Pay real close attention to phasing of all the
                                    transformers, one out
                                    of whack with throw the whole circuit off, possibly to
                                    the point of
                                    making it a relatively high powered VHF oscillator

                                    I also use a slightly different biasing scheme, I use
                                    different
                                    resistors at the base to set my current and keep a
                                    fixed 51 ohm
                                    resistor on the input/emitter to get a better 50 ohm
                                    input/output
                                    impedance match ... basically my biasing values are
                                    the same as this
                                    in my SDR http://www.qrp.pops.net/preamp.htm (bottom
                                    of page)

                                    Unless you need a balanced circuit (an untuned loop
                                    for example)
                                    and/or have a REALLY strong mixer (A +17 DBM or a
                                    Tayloe Detector)
                                    following it, you'd probably be as well or better off
                                    with a single
                                    transistor Norton amp ... it's also an advantage to
                                    use the push-pull
                                    setup for Direct Conversion because of the inherent
                                    2nd harmonic
                                    cancellation

                                    JR

                                    --- In loopantennas@yahoogroups.com, Paul Birke
                                    <nonlinear@...> wrote:
                                    >
                                    > very good JR
                                    >
                                    > thanks
                                    >
                                    > Paul
                                    >
                                    > any enhancements on Dallas' orginal article?
                                    > any further hints?
                                    > Dan's Part for the transistors I guess.
                                    >
                                    > Paul
                                    >
                                    >
                                    > --- jr_dakota <SG2112@...> wrote:
                                    >
                                    >
                                    > ---------------------------------
                                    > Yes, I'm using one in a SDR front end and have
                                    another
                                    > partially built
                                    > for a Wellbrook loop clone I'm working on .... They
                                    > are so bullet
                                    > proof you could put a full watt of power into them
                                    and
                                    > they'll hardly
                                    > burp .... the inherent 2nd harmonic cancellation
                                    (just
                                    > like a push
                                    > pull audio power amps) makes them especially
                                    > attractive in Direct
                                    > Conversion designs where IP2 is more important than
                                    > IP3 ... it's also
                                    > an excellent match to the Tayloe/QSD detector which
                                    > has an
                                    > outrageously high IP3 for a mixer so you need a
                                    preamp
                                    > with an
                                    > outrageously high IP3 so as not to degrade
                                    performance
                                    > ... this baby
                                    > is it .... there is also a similar design by Jacob
                                    > Makhinson, N6NWP
                                    > but it uses a bipolar supply for biasing and
                                    grounded
                                    > bases by the
                                    > slight performance increase isn't worth the hassle
                                    in
                                    > my opinion ...
                                    > then again I usually have a bipolar supply in most
                                    of
                                    > my designs for
                                    > audio frequency circuits (a bipolar supply opamp
                                    will
                                    > beat a single
                                    > supply in noise and power supply rejection every
                                    time)
                                    > so then it
                                    > wouldn't be a big deal
                                    >
                                    > JR
                                    >
                                    > --- In loopantennas@yahoogroups.com, Paul Birke
                                    > <nonlinear@> wrote:
                                    > >
                                    > >
                                    > >
                                    > >
                                    > > Found a bunch of 2N5109's for the Norton CBTF amps
                                    > > that the Lankford
                                    > > article describes, but haven't had a chance to
                                    > build
                                    > > one for LF yet.
                                    > >
                                    > > hi Joe et al
                                    > >
                                    > >
                                    > > Has anyone in the group built and tried out these
                                    > > amps?
                                    > >
                                    > > Paul
                                    > >
                                    >
                                    >
                                    >
                                    >
                                    >
                                    >
                                    > If you've got links, post them in the Links section!
                                    > http://groups.yahoo.com/group/loopantennas/links
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