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Re: [softrock40] Miniboots amp idea using Mobo minifilters

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  • Graham
    As far as I can see this amplifier has no forward bias .. it may be suitable for C.W. or FSK but not for any linear mode operation ... have I missed something
    Message 1 of 18 , Mar 2 2:51 AM
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      As far as I can see this amplifier has no forward bias .. it may be suitable for C.W. or FSK but not for any linear mode operation ... have I missed something ?
       
       
      ----- Original Message -----
      From: Alan
      Sent: Wednesday, March 02, 2011 10:39 AM
      Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters

       


      ----- Original Message -----
      From: "John Williams"
      Subject: [softrock40] Miniboots amp idea using Mobo minifilters

      >I have most of the parts in the shack except for the
      > LPF stage.
      >
      > http://www.amqrp.org/kits/miniboots/miniboot.htm
      >
      > I have been also contemplating getting a Mobo eventually. The design of
      > the TX part of the mobo uses the minifilters as TX BPF prior to the PA
      > stage. I don't see any LPF after the PA on the MOBO (but I could be
      > missing something). Can I use a similar approach on the miniboots and
      > skip the LPF and rely on the bandpass of the Ensemble itself or
      > alternatively can I buy a minifilter kit and insert the appropriate
      > minifilter between the ensemble and the miniboots amp? That would be a
      > cool way to approach the problem and give me parts to reuse later.
      >

      No. Any amplifier needs LPFs. It is to reduce the second, and higher,
      harmonics produced by the amplifier itself.
      The Ensemble 40/30/20 comes with components for a 40m LPF that needs to be
      used when this Ensemble is used on 40m.
      All amplifiers produce harmonics, all amplifiers require the appropriate
      LPFs.
      The mobo must require external LPFs if it has none on-board.

      73 Alan G4ZFQ

    • Alan
      ... From: Graham Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters ... No, you have not! This is an add-on for a SMK-1 CW transceiver, so
      Message 2 of 18 , Mar 2 3:00 AM
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        ----- Original Message -----
        From: "Graham
        Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters


        >As far as I can see this amplifier has no forward bias .. it may be
        >suitable for C.W. or FSK but not for any linear mode operation ... have I
        >missed something ?

        No, you have not!
        This is an add-on for a SMK-1 CW transceiver, so not to be used for SSB or
        any linear mode.

        73 Alan G4ZFQ
      • John Williams
        Glad I asked! Some of the acronyms are killing me in this new hobby... ... -- John Williams WQKA523 KE5SSH
        Message 3 of 18 , Mar 2 3:08 AM
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          Glad I asked! Some of the acronyms are killing me in this new hobby...

          On 3/2/2011 5:00 AM, Alan wrote:
           


          ----- Original Message -----
          From: "Graham
          Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters

          >As far as I can see this amplifier has no forward bias .. it may be
          >suitable for C.W. or FSK but not for any linear mode operation ... have I
          >missed something ?

          No, you have not!
          This is an add-on for a SMK-1 CW transceiver, so not to be used for SSB or
          any linear mode.

          73 Alan G4ZFQ


          -- 
          
          John Williams
          WQKA523
          KE5SSH
          
        • John Williams
          So, maybe I will just throw it together single band with the 40M LPF and use it for PSK31? ... -- John Williams WQKA523 KE5SSH
          Message 4 of 18 , Mar 2 3:12 AM
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            So, maybe I will just throw it together single band with the 40M LPF and use it for PSK31?

            On 3/2/2011 5:00 AM, Alan wrote:
             


            ----- Original Message -----
            From: "Graham
            Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters

            >As far as I can see this amplifier has no forward bias .. it may be
            >suitable for C.W. or FSK but not for any linear mode operation ... have I
            >missed something ?

            No, you have not!
            This is an add-on for a SMK-1 CW transceiver, so not to be used for SSB or
            any linear mode.

            73 Alan G4ZFQ


            -- 
            
            John Williams
            WQKA523
            KE5SSH
            
          • Alan
            ... From: John Williams Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters ... I have made some SSB QSOs with 1/2 watt but random ones may
            Message 5 of 18 , Mar 2 3:23 AM
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              ----- Original Message -----
              From: "John Williams"
              Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters


              > So, maybe I will just throw it together single band with the 40M LPF and
              > use it for PSK31?
              >

              I have made some SSB QSOs with 1/2 watt but random ones may need a little
              patience.
              There have been lots of discussions in the past, from my web page:-

              ""Lots of discussion about PAs for use with Softrocks .. ...Some amplifier
              suggestions if you are not a true QRPer....
              My experience with IRF510s is not a good one, they never managed to behave
              properly above 14MHz. And their IMD performance is not good since they are
              not RF devices.
              Here are some links for QRP PAs with RD15HVF01 and RD16HHF1
              1.-> http://www.kolumbus.fi/juha.niinikoski/10WLinear/10WLinear.htm
              2.-> http://www.box73.de/catalog/pdf/PLB-15.pdf
              3.-> http://myweb.tiscali.co.uk/radiokits/radio-related/20W_PA/
              4.-> http://qrpproject.de/UK/QRPPA2008UK.html <-my favorite !!
              Numbers 1. and 3. are homebrew designs whereas 2. and 4. are offered as
              kits. My preferred one though is the fourth which is permanently now in the
              same box as my softrock and the one you hear when we have qso's on 10m 73,
              Christos SV1EIA""

              I expect others will now join in..


              73 Alan G4ZFQ
            • Alan
              ... From: John Williams Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters John, I decided to look at those links and see they are not so
              Message 6 of 18 , Mar 2 3:36 AM
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                ----- Original Message -----
                From: "John Williams"
                Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters


                John,

                I decided to look at those links and see they are not so useful now!
                The first looks OK, the last is really too sensitive but could be used with
                care (and attenuator).

                But it is a topic that usually gets lots of recommendations.

                73 Alan G4ZFQ
              • John Williams
                Alan, Have you looked at the Pennywhistle? Seems to be a current design that has a reasonable kit cost and available here in the US.
                Message 7 of 18 , Mar 2 4:07 AM
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                  Alan,

                  Have you looked at the Pennywhistle? Seems to be a current design that has a reasonable kit cost and available here in the US.

                  https://www.tapr.org/kits_pw.html

                  John

                  On 3/2/2011 5:36 AM, Alan wrote:
                   


                  ----- Original Message -----
                  From: "John Williams"
                  Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters

                  John,

                  I decided to look at those links and see they are not so useful now!
                  The first looks OK, the last is really too sensitive but could be used with
                  care (and attenuator).

                  But it is a topic that usually gets lots of recommendations.

                  73 Alan G4ZFQ


                  -- 
                  
                  John Williams
                  WQKA523
                  KE5SSH
                  
                • g8voip
                  Hi John, The v4.3 mobo definately needs to have additional LPF fitted after the PA stage, something which has caught out a lot people and not made very clear
                  Message 8 of 18 , Mar 2 4:17 AM
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                    Hi John,

                    The v4.3 mobo definately needs to have additional LPF fitted after the PA stage, something which has caught out a lot people and not made very clear in any of the documentation.

                    A lot have used the HF Projects module which can be controlled using an additional I2C extender module. Both of couse add additional expense to the project.

                    73, Bob G8VOI

                    --- In softrock40@yahoogroups.com, John Williams <KE5SSH@...> wrote:
                    >
                    > I have an Ensemble RXTX 40/30/20 that I want to boost the power a bit
                    > for SSB. I am going to build the Miniboots amp since it is so
                    > simple/cheap and I have most of the parts in the shack except for the
                    > LPF stage.
                    >
                    > http://www.amqrp.org/kits/miniboots/miniboot.htm
                    >
                    > I have been also contemplating getting a Mobo eventually. The design of
                    > the TX part of the mobo uses the minifilters as TX BPF prior to the PA
                    > stage. I don't see any LPF after the PA on the MOBO (but I could be
                    > missing something). Can I use a similar approach on the miniboots and
                    > skip the LPF and rely on the bandpass of the Ensemble itself or
                    > alternatively can I buy a minifilter kit and insert the appropriate
                    > minifilter between the ensemble and the miniboots amp? That would be a
                    > cool way to approach the problem and give me parts to reuse later.
                    >
                    > --
                    >
                    > John Williams
                    > WQKA523
                    > KE5SSH
                    >
                  • k5nwa
                    Be aware that amplifier as is a Class C amplifier, not usable for any mode that requires a linear amplifier, its good for CW. The answer is the Miniboots
                    Message 9 of 18 , Mar 2 6:33 AM
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                      Be aware that amplifier as is a Class C amplifier, not usable for any
                      mode that requires a linear amplifier, its good for CW. The answer is
                      the Miniboots requires a filter on the output as it's a non-linear
                      amplifier and put out harmonics all over the place. There are other
                      sites that modify the mini-boots to be linear but even then a single
                      ended amplifier tends to have a lot of distortion.

                      A much better amplifier is the TAPR Pennywhislle, it's linear, takes
                      about 1/4 to 1/2 watt input which matches the SoftRocks being used
                      properly, and puts out 16 Watts.

                      At 04:23 AM 3/2/2011, you wrote:
                      >I have an Ensemble RXTX 40/30/20 that I want to boost the power a bit
                      >for SSB. I am going to build the Miniboots amp since it is so
                      >simple/cheap and I have most of the parts in the shack except for the
                      >LPF stage.
                      >
                      >http://www.amqrp.org/kits/miniboots/miniboot.htm
                      >
                      >I have been also contemplating getting a Mobo eventually. The design of
                      >the TX part of the mobo uses the minifilters as TX BPF prior to the PA
                      >stage. I don't see any LPF after the PA on the MOBO (but I could be
                      >missing something). Can I use a similar approach on the miniboots and
                      >skip the LPF and rely on the bandpass of the Ensemble itself or
                      >alternatively can I buy a minifilter kit and insert the appropriate
                      >minifilter between the ensemble and the miniboots amp? That would be a
                      >cool way to approach the problem and give me parts to reuse later.
                      >
                      >--
                      >
                      >John Williams
                      >WQKA523
                      >KE5SSH

                      Cecil
                      k5nwa
                      < www.softrockradio.org > < www.qrpradio.com >
                      < http://parts.softrockradio.org/ >

                      Never take life seriously. Nobody gets out alive anyway.
                    • prhorne@aol.com
                      Hi John Iv e been using a Pennywhistle PA in conjunction with my softrock V6.3 and mobo for about 6months. It performs extremely well, but it also needs and
                      Message 10 of 18 , Mar 2 8:49 AM
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                        Hi John Iv'e been using a Pennywhistle PA in conjunction with my softrock V6.3 and mobo for about 6months. It performs extremely well, but it also needs and external set of LPS's as Alan has said to reduce the 2nd & 3rd harmonics. I mostly use it for PSK31.
                        73's Peter G3JRH




                        -----Original Message-----
                        From: John Williams <KE5SSH@...>
                        To: softrock40@yahoogroups.com
                        Sent: Wed, 2 Mar 2011 12:07
                        Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters

                         
                        Alan,

                        Have you looked at the Pennywhistle? Seems to be a current design that has a reasonable kit cost and available here in the US.

                        https://www.tapr.org/kits_pw.html

                        John

                        On 3/2/2011 5:36 AM, Alan wrote:
                         

                        ----- Original Message -----
                        From: "John Williams"
                        Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters

                        John,

                        I decided to look at those links and see they are not so useful now!
                        The first looks OK, the last is really too sensitive but could be used with
                        care (and attenuator).

                        But it is a topic that usually gets lots of recommendations.

                        73 Alan G4ZFQ


                        -- 

                        John Williams
                        WQKA523
                        KE5SSH
                      • Eric Söderman
                        Hi, In the magazine HOMEBREWER Summer 2003 edition there is an article named SSB Mods for Minboots CW Amp Eric SA5BKE
                        Message 11 of 18 , Mar 2 9:13 AM
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                          Hi,

                          In the magazine HOMEBREWER Summer 2003 edition there is an article
                          named "SSB Mods for Minboots CW Amp"

                          Eric SA5BKE

                          On Wed, Mar 2, 2011 at 12:08 PM, John Williams <KE5SSH@...> wrote:
                          >
                          >
                          >
                          > Glad I asked! Some of the acronyms are killing me in this new hobby...
                          >
                          > On 3/2/2011 5:00 AM, Alan wrote:
                          >
                          >
                          >
                          > ----- Original Message -----
                          > From: "Graham
                          > Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters
                          >
                          > >As far as I can see this amplifier has no forward bias .. it may be
                          > >suitable for C.W. or FSK but not for any linear mode operation ... have I
                          > >missed something ?
                          >
                          > No, you have not!
                          > This is an add-on for a SMK-1 CW transceiver, so not to be used for SSB or
                          > any linear mode.
                        • JOHN GREUSEL
                          Hi Eric, Is there a link to that article? If not could you briefly summarize? Thanks, John KC9OJV ... From: Eric Söderman Subject: Re:
                          Message 12 of 18 , Mar 2 9:19 AM
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                            Hi Eric,

                            Is there a link to that article? If not could you briefly summarize?

                            Thanks,
                            John
                            KC9OJV

                            --- On Wed, 3/2/11, Eric Söderman <eric@...> wrote:

                            From: Eric Söderman <eric@...>
                            Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters
                            To: softrock40@yahoogroups.com
                            Date: Wednesday, March 2, 2011, 11:13 AM

                             

                            Hi,

                            In the magazine HOMEBREWER Summer 2003 edition there is an article
                            named "SSB Mods for Minboots CW Amp"

                            Eric SA5BKE

                            On Wed, Mar 2, 2011 at 12:08 PM, John Williams <KE5SSH@...> wrote:
                            >
                            >
                            >
                            > Glad I asked! Some of the acronyms are killing me in this new hobby...
                            >
                            > On 3/2/2011 5:00 AM, Alan wrote:
                            >
                            >
                            >
                            > ----- Original Message -----
                            > From: "Graham
                            > Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters
                            >
                            > >As far as I can see this amplifier has no forward bias .. it may be
                            > >suitable for C.W. or FSK but not for any linear mode operation ... have I
                            > >missed something ?
                            >
                            > No, you have not!
                            > This is an add-on for a SMK-1 CW transceiver, so not to be used for SSB or
                            > any linear mode.

                          • skarbows
                            My experience with the Pennywhistle on 75 and 40 meters has also been very favorable. Easy to build, worked first time and takes little drive to make full
                            Message 13 of 18 , Mar 2 9:44 AM
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                              My experience with the Pennywhistle on 75 and 40 meters has also been very favorable. Easy to build, worked first time and takes little drive to make full output. Great for a RXTX6.3 - lets it run around 1/4 watt where its nice and clean.

                              Dave
                              kx3dx

                              --- In softrock40@yahoogroups.com, k5nwa <k5nwa@...> wrote:
                              >
                              > Be aware that amplifier as is a Class C amplifier, not usable for any
                              > mode that requires a linear amplifier, its good for CW. The answer is
                              > the Miniboots requires a filter on the output as it's a non-linear
                              > amplifier and put out harmonics all over the place. There are other
                              > sites that modify the mini-boots to be linear but even then a single
                              > ended amplifier tends to have a lot of distortion.
                              >
                              > A much better amplifier is the TAPR Pennywhislle, it's linear, takes
                              > about 1/4 to 1/2 watt input which matches the SoftRocks being used
                              > properly, and puts out 16 Watts.
                              >
                            • The Silver Fox
                              http://www.amqrp.org/hbextra/index.html From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of Eric Söderman Sent: Wednesday, March
                              Message 14 of 18 , Mar 2 11:18 AM
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                                http://www.amqrp.org/hbextra/index.html

                                 

                                From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of Eric Söderman
                                Sent: Wednesday, March 02, 2011 9:13 AM
                                To: softrock40@yahoogroups.com
                                Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters

                                 

                                 

                                Hi,

                                In the magazine HOMEBREWER Summer 2003 edition there is an article
                                named "SSB Mods for Minboots CW Amp"

                                Eric SA5BKE

                                On Wed, Mar 2, 2011 at 12:08 PM, John Williams <KE5SSH@...> wrote:
                                >
                                >
                                >
                                > Glad I asked! Some of the acronyms are killing me in this new hobby...
                                >
                                > On 3/2/2011 5:00 AM, Alan wrote:
                                >
                                >
                                >
                                > ----- Original Message -----
                                > From: "Graham
                                > Subject: Re: [softrock40] Miniboots amp idea using Mobo minifilters
                                >
                                > >As far as I can see this amplifier has no forward bias .. it may be
                                > >suitable for C.W. or FSK but not for any linear mode operation ... have I
                                > >missed something ?
                                >
                                > No, you have not!
                                > This is an add-on for a SMK-1 CW transceiver, so not to be used for SSB or
                                > any linear mode.

                              • Sid Boyce
                                ... The Mobo needs the external LPF s. There is an add-on 8574 board, I2C controlled that is able to select external filters and cooling fans via the ULN2803
                                Message 15 of 18 , Mar 2 5:59 PM
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                                  On 02/03/11 10:23, John Williams wrote:
                                  > I have an Ensemble RXTX 40/30/20 that I want to boost the power a bit
                                  > for SSB. I am going to build the Miniboots amp since it is so
                                  > simple/cheap and I have most of the parts in the shack except for the
                                  > LPF stage.
                                  >
                                  > http://www.amqrp.org/kits/miniboots/miniboot.htm
                                  >
                                  > I have been also contemplating getting a Mobo eventually. The design of
                                  > the TX part of the mobo uses the minifilters as TX BPF prior to the PA
                                  > stage. I don't see any LPF after the PA on the MOBO (but I could be
                                  > missing something). Can I use a similar approach on the miniboots and
                                  > skip the LPF and rely on the bandpass of the Ensemble itself or
                                  > alternatively can I buy a minifilter kit and insert the appropriate
                                  > minifilter between the ensemble and the miniboots amp? That would be a
                                  > cool way to approach the problem and give me parts to reuse later.
                                  >
                                  > --
                                  >
                                  > John Williams
                                  > WQKA523
                                  > KE5SSH
                                  >

                                  The Mobo needs the external LPF's. There is an add-on 8574 board, I2C
                                  controlled that is able to select external filters and cooling fans via
                                  the ULN2803 driver IC on the board. The switch over frequencies for each
                                  band is set by a python utility - MoboControl.py.

                                  I just wired one in an hour ago to switch the LPF's on the M0RZF 20W PA
                                  which is ready for installation.

                                  One other consideration, the power handling capacity of the minifilters
                                  - I haven't seen that discussed, but the capacitors are 50VW which would
                                  probably handle the miniboot.
                                  73 ... Sid.
                                  --
                                  Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                                  Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                                  Senior Staff Specialist, Cricket Coach
                                  Microsoft Windows Free Zone - Linux used for all Computing Tasks
                                • ke4id
                                  Hi, John, I built an 80M/40M Ensemble RXTX earlier this year. The initial power power boost comes from a HEXFET amp shown in Experimental Methods in RF
                                  Message 16 of 18 , Mar 2 8:06 PM
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                                    Hi, John,
                                    I built an 80M/40M Ensemble RXTX earlier this year. The initial power power boost comes from a HEXFET amp shown in "Experimental Methods in RF Design" by W7ZOI and company. It is on page 2.36, Figure 2.98. It is forward biased to draw 100 mA for SSB use.

                                    I added a negative feedback loop from the gate to the drain, consisting of a 4.7 k resistor in series with a .1 uF cap, to cure some instability. Measured gain is 18db.

                                    Here is the total SDR setup:
                                    -Outboard Control Module: this was built to externally key the SoftRock, two amplifiers and the input to the sound system. Parts were soldered to the tin project box, purchased from Michael's. Solder lugs were also used.

                                    -HEXFET amp with built-in relay. This is keyed by the Outboard Control Module. This is also in a tin project box.

                                    -Outboard Low Pass Filer for 80M (my band of interest these days). This small unit is in an Altoids box.

                                    -Ameritron AL-811H tube amp. This is also keyed by the Outboard Control Module.

                                    -A foot switch is used for the PTT function.

                                    -Connections are via BNC jumpers. I get about 140 watts out on SSB. It works great on AM, too.

                                    A critical feature to turn on in PowerSDR v1.19.3.15 is the TR sequencing. This can be found in the tool bar: Setup-->General-->Options--> check the box for Enable X2TR Sequencing. I use an X2 delay setting of 60.

                                    Best regards,
                                    Jack



                                    --- In softrock40@yahoogroups.com, John Williams <KE5SSH@...> wrote:
                                    >
                                    > I have an Ensemble RXTX 40/30/20 that I want to boost the power a bit ........
                                    >
                                    > John Williams
                                    > WQKA523
                                    > KE5SSH
                                    >
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