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laptop RFI--help!

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  • aflowers@frontiernet.net
    Hi folks, The new K0SM rover just made it s maiden voyage down the street. I ve upgraded to more metal, and given that I was S4 down in EM25 I think it s
    Message 1 of 13 , Dec 19, 2004
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      Hi folks,

      The new K0SM rover just made it's maiden voyage down the street. I've
      upgraded to more metal, and given that I was S4 down in EM25 I think
      it's working. My big problem right now is the noise generated by the
      computer. It appears to be when the computer is plugged into the
      ciggarette lighter in the Honda CRV. All other stuff is directly to
      the battery via a rigrunner interface. I wonder what solutions people
      have come up with. Right now it's pretty crippling as it raises the
      noise floor about 20 dB. I'm using a compaq presario of 1999 vintage I
      think, with a standard 12V-19V DC-DC converter on the input. the
      converter doesn't seem to be too noisy--just when the computer is
      turned on.

      I'll try another laptop in the meantime, but i wonder if anyone has any
      experience with this and can offer some pointers. The older, more
      well-behaved computer is SK now...

      Andy K0SM
    • jeff millar
      Andy... Several of the chargers I ve used in the last year have the most horrific RFI. Some ideas... * Ferrites on the output lead, close to the charger *
      Message 2 of 13 , Dec 19, 2004
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        Andy...

        Several of the chargers I've used in the last year have the most horrific RFI.  Some ideas...
        • Ferrites on the output lead, close to the charger
        • Ferrites on the DC power lead, close to the charger
        If it's not the charger...
        • Ferrites on the rigblaster, placed close to the comput
        • Ferrites on the charger lead, close to the compute
        Determine if it broad band from harmonics of a 100 kHz switcher or narrowband from the computer bus
        • Change the bios clock frequency
        • Enable spread spectrum mode
        Hope  one of those helps...

        jeff, wa1hco

        aflowers@... wrote:
        Hi folks,
        
        The new K0SM rover just made it's maiden voyage down the street.  I've
        upgraded to more metal, and given that I was S4 down in EM25 I think
        it's working.  My big problem right now is the noise generated by the
        computer.  It appears to be when the computer is plugged into the
        ciggarette lighter in the Honda CRV.  All other stuff is directly to
        the battery via a rigrunner interface.  I wonder what solutions people
        have come up with.  Right now it's pretty crippling as it raises the
        noise floor about 20 dB.  I'm using a compaq presario of 1999 vintage I
        think, with a standard 12V-19V DC-DC converter on the input.  the
        converter doesn't seem to be too noisy--just when the computer is
        turned on.
        
        I'll try another laptop in the meantime, but i wonder if anyone has any
        experience with this and can offer some pointers.  The older, more
        well-behaved computer is SK now...
        
        Andy K0SM
        
        
        
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      • Jon W0AMT
        Hi Andy, You mention a 12V-19V DC-DC converter, they can be very noisy. Does the noise drop when the laptop is running on battery alone? The laptop I have
        Message 3 of 13 , Dec 19, 2004
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          Hi Andy,

          You mention a 12V-19V DC-DC converter, they can be very noisy. Does the
          noise drop when the laptop is running on battery alone? The laptop I
          have used for roving is an older compaq it is pretty quiet except when
          the external power supply has to charge the battery as well as operate
          the laptop. When the computer has stopped charging the battery the noise
          is very low. My only other suggestion is to try a different DC-DC
          Converter. The best ones I have found are made by Zahn Electronics.
          http://www.zahninc.com/

          73, Jon
          W0AMT


          -----Original Message-----
          From: aflowers@... [mailto:aflowers@...]
          Sent: Sunday, December 19, 2004 2:18 PM
          To: wsjtgroup@yahoogroups.com
          Subject: [wsjtgroup] laptop RFI--help!


          Hi folks,

          The new K0SM rover just made it's maiden voyage down the street. I've
          upgraded to more metal, and given that I was S4 down in EM25 I think it's
          working. My big problem right now is the noise generated by the
          computer. It appears to be when the computer is plugged into the
          ciggarette lighter in the Honda CRV. All other stuff is directly to the
          battery via a rigrunner interface. I wonder what solutions people have
          come up with. Right now it's pretty crippling as it raises the noise
          floor about 20 dB. I'm using a compaq presario of 1999 vintage I think,
          with a standard 12V-19V DC-DC converter on the input. the converter
          doesn't seem to be too noisy--just when the computer is turned on.

          I'll try another laptop in the meantime, but i wonder if anyone has any
          experience with this and can offer some pointers. The older, more
          well-behaved computer is SK now...

          Andy K0SM
        • Dan
          Hi Andy, I recently had the same trouble. I upgraded to an IBM Thinkpad, and while running on battery it s perfectly quiet. But when on the 12v cord there
          Message 4 of 13 , Dec 19, 2004
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            Hi Andy,

            I recently had the same trouble. I upgraded to an IBM Thinkpad, and
            while running on battery it's perfectly quiet. But when on the 12v cord
            there was terrible noise. I was using a cheap after market cord that
            was the problem. I went to ebay and bought an actual IBM Thinkpad dc
            cord, and haven't had any trouble since.

            Good luck,
            Dan

            --
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            Check out the Rover Resource Page at: http://www.qsl.net/n9rla
            List Administrator for: InHam+grid-loc+ham-books
          • aflowers@frontiernet.net
            Here s an update on the situation.... I went out to the car with fairly new Gateway 450. I ran it on the battery to see if that was the issue. It wasn t.
            Message 5 of 13 , Dec 19, 2004
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              Here's an update on the situation....
              I went out to the car with fairly new Gateway 450. I ran it on the
              battery to see if that was the issue. It wasn't. It's a great
              weak-signal noise source on 144 MHz anywhere withing 50ft of the car,
              though I found that it had quite a bit of directionality--yes, I turned
              off the wireless card. I don't know about the older Compaq Presario and
              it's battery bit the dust long ago so that I can only run it with the
              cord. It looks like the same problem since there is no QRM with the
              DC-DC converter plugged in with the computer off. I'm willing to bet
              that this is all because there is alot of DC-DC switching after the
              battery, in which case you are going to be screwed no matter what you
              do.

              I might experiment with some aluminum foil from the kitchen and see what
              I can do. I don't think the directionality is going to be helpful when
              the computer is below the antenna though. Makes me think I need to go
              out and buy a really cheap thinkpad. It's gotta be possible to run WSJT
              (at least FSK441) on something that costs less that $100 now...

              Andy K0SM


              Quoting Dan <n9rla@...>:

              >
              > Hi Andy,
              >
              > I recently had the same trouble. I upgraded to an IBM Thinkpad, and
              > while running on battery it's perfectly quiet. But when on the 12v
              > cord
              > there was terrible noise. I was using a cheap after market cord that
              > was the problem. I went to ebay and bought an actual IBM Thinkpad dc
              > cord, and haven't had any trouble since.
              >
              > Good luck,
              > Dan
              >
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              > K9ZF /R no budget Rover ***QRP-l #1269
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              > List Administrator for: InHam+grid-loc+ham-books
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            • Bruce Brackin
              Andy - not sure how well behaved the Compac would be, but I run older Thinkpad right off lighter out (~13.6 vdc). Its charger is 16 or 17 vdc and while it
              Message 6 of 13 , Dec 19, 2004
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                Andy - not sure how well behaved the Compac would be, but I run older
                Thinkpad right off lighter out (~13.6 vdc). Its charger is 16 or 17 vdc
                and while it wont top off charge, it runs weeks/months at a time fed
                with 13.6 in the truck. Until I had some amp grounding issues, I'd
                never needed any beads on power cord and that was not the real problem
                after the fact. I try to remember to bring it in occasionally and use
                real charger, particularly in cold weather.

                Bruce, N5SIX
              • aflowers@frontiernet.net
                It seems like most folks have been using thinkpads in a rover environment. Can you throw some model # s at me that are known to be quiet? I might go down to
                Message 7 of 13 , Dec 19, 2004
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                  It seems like most folks have been using thinkpads in a rover
                  environment. Can you throw some model #'s at me that are known to be
                  quiet? I might go down to the used computer place and see if I can dig
                  something up. If worse comes to worse I can set the antenna on a
                  portable mast away from the car, but I'd like to avoid doing that if I
                  can.

                  Andy K0SM



                  Quoting Bruce Brackin <bbrackin@...>:

                  >
                  > Andy - not sure how well behaved the Compac would be, but I run older
                  > Thinkpad right off lighter out (~13.6 vdc). Its charger is 16 or 17
                  > vdc
                  > and while it wont top off charge, it runs weeks/months at a time fed
                  > with 13.6 in the truck. Until I had some amp grounding issues, I'd
                  > never needed any beads on power cord and that was not the real
                  > problem
                  > after the fact. I try to remember to bring it in occasionally and
                  > use
                  > real charger, particularly in cold weather.
                  >
                  > Bruce, N5SIX
                  >
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                • Bruce Brackin
                  Andy - mine is older 166 MHz 380D with big 48 MB ram - OK for FSK and JT6m and JT44 (6-8 sec decode) but lets just say you probably don t want to run much
                  Message 8 of 13 , Dec 19, 2004
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                    Andy - mine is older 166 MHz 380D with big 48 MB ram - OK for FSK and
                    JT6m and JT44 (6-8 sec decode) but lets just say you probably don't want
                    to run much JT65! No USB but little newer models added it. I run a
                    Eiger Lab PCMCIA serial card to get 2nd com port for GPS. Not sure
                    about other Thinkpads but this has unbeleivable accurate realtime
                    clock. I thought I'd be smart and get a PCMCIA USB card for different
                    mouse style GPS I have and found out you need 32 bit card slot to get
                    USB to work - older Thinkpads had 16 bit slots so one thing to ask about.

                    If I upgrade the mobile PC, it will be "new" old Thinkpad - the stick
                    mouse/pointer is easier to work on the road than touchpad. Several
                    used/referbed places have some up to 500-700 Mhz for good price now.

                    Bruce, N5SIX
                  • Dan
                    Hi Andy I m using a 560x that I picked up on ebay for around $100. It s certainly no speed demon, but seems fine for our purposes. My main requirements were
                    Message 9 of 13 , Dec 19, 2004
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                      Hi Andy

                      I'm using a 560x that I picked up on ebay for around $100.

                      It's certainly no speed demon, but seems fine for our purposes. My main
                      requirements were running WSJT, logging [Roverlog], voice and CW keying,
                      and eventually HamIM... Pretty heavy load, huh?

                      So far the 560x has done it all, except HamIM that I haven't taken time
                      to get running yet. Anyway, the 560x has a Pentium 233MHz, 64Mb RAM,
                      and 2 Gig HD.

                      Anything else I can help with just drop me a line.
                      Dan

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                      K9ZF /R no budget Rover ***QRP-l #1269
                      Check out the Rover Resource Page at: http://www.qsl.net/n9rla
                      List Administrator for: InHam+grid-loc+ham-books
                    • Dan
                      Forgot to mention, the DC cable doesn t make noise unless it s passing current. For example, I used to leave it plugged in, and just unplug it from the
                      Message 10 of 13 , Dec 19, 2004
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                        Forgot to mention, the DC cable doesn't make noise unless it's passing
                        current. For example, I used to leave it plugged in, and just unplug it
                        from the computer when making QSO's...

                        73
                        Dan

                        --
                        K9ZF /R no budget Rover ***QRP-l #1269
                        Check out the Rover Resource Page at: http://www.qsl.net/n9rla
                        List Administrator for: InHam+grid-loc+ham-books
                      • Russ K2TXB
                        Hi Andy, I had a Thinkpad model TP-600E that I used to use for portable and auxillary WSJT operations. It was a 330 MHz Pentium 2, and while it worked ok, it
                        Message 11 of 13 , Dec 19, 2004
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                          Hi Andy, I had a Thinkpad model TP-600E that I used to use for portable and
                          auxillary WSJT operations. It was a 330 MHz Pentium 2, and while it worked
                          ok, it was pretty slow for JT65. You definitely had to use the 'slow CPU'
                          option. But I concur that it had no noise. I think one could probably pick
                          up a used TP-600? in the range of $300 and up.

                          My new laptop is a Dell Inspiron 600M, and it is bloody fast. Decodes JT65
                          sequences in about a second (it took the thinkpad up to 20 seconds), and
                          FSK441 decodes just about instantaneously. I have noticed no noise from the
                          Dell, either with or without the charger, but have not yet used it in a
                          portable environment. It does sit right beside my 2 two meter receivers,
                          and it is connected to the internet via RF, and no interference either way.

                          By the way, the Thinkpad, new, cost me over $4200, while the new Dell with
                          all kinds of accessories like an extra portable (car/airplane/wall) charger,
                          leather carrying case, docking station, 1.6 Ghz Pentium 4, 60 Gig hard
                          drive, 512 meg memory, 2 meg USB ram drive, and wireless mouse, cost only
                          around $1800. See, you can get more for less. I would have bought another
                          Thinkpad, but the current models just did not stand up to the Dell in terms
                          of features, performance, or price.

                          73, Russ K2TXB

                          > -----Original Message-----
                          > From: aflowers@... [mailto:aflowers@...]
                          > Sent: Sunday, December 19, 2004 7:20 PM
                          > To: wsjtgroup@yahoogroups.com
                          > Subject: Re: [wsjtgroup] laptop RFI--help!
                          >
                          >
                          >
                          > It seems like most folks have been using thinkpads in a rover
                          > environment. Can you throw some model #'s at me that are known to be
                          > quiet? I might go down to the used computer place and see if I can dig
                          > something up. If worse comes to worse I can set the antenna on a
                          > portable mast away from the car, but I'd like to avoid doing that if I
                          > can.
                          >
                          > Andy K0SM
                          >
                          >
                          >
                          > Quoting Bruce Brackin <bbrackin@...>:
                          >
                          > >
                          > > Andy - not sure how well behaved the Compac would be, but I run older
                          > > Thinkpad right off lighter out (~13.6 vdc). Its charger is 16 or 17
                          > > vdc
                          > > and while it wont top off charge, it runs weeks/months at a time fed
                          > > with 13.6 in the truck. Until I had some amp grounding issues, I'd
                          > > never needed any beads on power cord and that was not the real
                          > > problem
                          > > after the fact. I try to remember to bring it in occasionally and
                          > > use
                          > > real charger, particularly in cold weather.
                          > >
                          > > Bruce, N5SIX
                          > >
                          > >
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                        • Mike H
                          I used the Thinkpad 760 with a 166 MHz processor, 64 Mb, and W95. It was $200 on ebay. I recall that it took about 4-5 seconds to decode FSK441a. I ran it
                          Message 12 of 13 , Dec 19, 2004
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                            I used the Thinkpad 760 with a 166 MHz processor, 64 Mb, and W95. It was
                            $200 on ebay. I recall that it took about 4-5 seconds to decode FSK441a.
                            I ran it from the same deep cycle battery that powered the radio. Never
                            got near the cig lighter adaptor. To make this work, I connected a female
                            cig adaptor to the battery to accomodate the laptop's 12V power cord.
                            Note that I use 'past tense' here as most of my WSJT rover equipment was
                            stolen this past summer when I got burglarized. Andy: if you'd like the
                            female cig adaptor, which was left behind, let me know.

                            Mike WB2FKO
                          • SP8RHP
                            Hi All... I have similar problem how Andy K0SM... He manifests itself this : noise changes during bowing matrix (screen) from S1 -S5-6. How do to remedy this
                            Message 13 of 13 , Dec 20, 2004
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                              Hi All...
                              I have similar problem how Andy K0SM...
                              He manifests itself this : noise changes during bowing matrix (screen) from S1 -S5-6.
                              How do to remedy this ??? .
                              Someone had similar problems maybe and it knows how from this to fight ? .
                              Laptoop this HP4150 366MHz 192RAM...
                              I used once Toshiba Satellite Pro 166MHz and nothing of the sort did not it notice ..
                              enlargement of level of noise .
                              Metric TRX - HP4150 ~ 2 feets...
                              Bob SP8RHP




                              --
                              Pozdrowienia,
                              SP8RHP
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