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Sked and rx frequency - help and clarification

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  • Enrico - IZ0GYP
    Hi all, I m a novice for EME (QRP with 9 element and 200W) and i m still studying the JT65B to be more familiar with the communication procedures, trying to
    Message 1 of 5 , Nov 13, 2006
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      Hi all,

      I'm a novice for EME (QRP with 9 element and 200W) and i'm still
      studying the JT65B to be more familiar with the communication
      procedures, trying to avoid mistakes and loose of time to the stations
      that would reply to my skeds.
      Up to now i succesfully completed 3 QSOs.

      Anyhow my problem is the following.

      If someone, on the EME chat, state a CQ call on 137 (144.137) this
      means that both the calling station and the station that would like to
      reply to his call shall have the VFO on 137,0 during TX.

      Now, i'm using a FT-736R and i'm almost sure about correctness of the
      freq calibration.

      Usually a receive CQ station EME calls at SpecJT center when my VFO is
      approx. 0,7 KHz higher (144.137,7).
      Otherwise, leaving the VFO at 137,0 , i will see caller EME signals at
      the far right side of the SpecJT screen (or even outside).
      That's of course due to the Doppler effect but my concern is if 0,7
      KHz is a standard frequency doppler shift on VHF or is a little bit
      too big?
      Due to my QRP conditions i can't receive my own echoes and the other
      stations will see only light signals on their PCs.
      I would like also to be sure at least that i'm not spending time
      calling on a wrong frequency where the CQ caller station would never
      receive me.

      Shall i therefore use the second FT-736 VFO on 0,7 KHz higher during
      rx (FT-736R does not have independent RIT function)?

      Is my understanding correct that if i will be transmitting on the sked
      frequency also my EME signals will be "falling" in the center part of
      SpecJT screen of the other station (i guess that he will be also
      listening 0,7 KHz higher)?

      Sorry if the questions may be appear probably confused (or even
      terrible) to you but your help will be very appreciated on my side.

      Thanks for your kind reply and understandings


      Best 73's de Enrico - IZ0GYP
    • Lee Scott - AA1YN
      ... Hi Enrico, You are in the same situation I was in two years ago. Put his signal in the center of SpecJT s window. I don t know how you determined your
      Message 2 of 5 , Nov 13, 2006
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        At 08:58 AM 11/13/2006 +0000, Enrico - IZ0GYP wrote:
        >Hi all,
        >
        >I'm a novice for EME (QRP with 9 element and 200W) and i'm still
        >studying the JT65B to be more familiar with the communication
        >procedures, trying to avoid mistakes and loose of time to the stations
        >that would reply to my skeds.
        >Up to now i succesfully completed 3 QSOs.
        >
        >Anyhow my problem is the following.
        >
        >If someone, on the EME chat, state a CQ call on 137 (144.137) this
        >means that both the calling station and the station that would like to
        >reply to his call shall have the VFO on 137,0 during TX.
        >
        >Now, i'm using a FT-736R and i'm almost sure about correctness of the
        >freq calibration.
        >
        >Usually a receive CQ station EME calls at SpecJT center when my VFO is
        >approx. 0,7 KHz higher (144.137,7).
        >Otherwise, leaving the VFO at 137,0 , i will see caller EME signals at
        >the far right side of the SpecJT screen (or even outside).
        >That's of course due to the Doppler effect but my concern is if 0,7
        >KHz is a standard frequency doppler shift on VHF or is a little bit
        >too big?
        >Due to my QRP conditions i can't receive my own echoes and the other
        >stations will see only light signals on their PCs.
        >I would like also to be sure at least that i'm not spending time
        >calling on a wrong frequency where the CQ caller station would never
        >receive me.
        >
        >Shall i therefore use the second FT-736 VFO on 0,7 KHz higher during
        >rx (FT-736R does not have independent RIT function)?
        >
        >Is my understanding correct that if i will be transmitting on the sked
        >frequency also my EME signals will be "falling" in the center part of
        >SpecJT screen of the other station (i guess that he will be also
        >listening 0,7 KHz higher)?
        >
        >Sorry if the questions may be appear probably confused (or even
        >terrible) to you but your help will be very appreciated on my side.
        >
        >Thanks for your kind reply and understandings
        >
        >
        >Best 73's de Enrico - IZ0GYP

        Hi Enrico,

        You are in the same situation I was in two years ago. Put his signal in the
        center of SpecJT's window. I don't know how you determined your FT-736
        frequency's accuracy but I would bet you are at least 500 Hz off. I don't
        know what the Moon's Doppler effect was at the time you were trying to
        contact someone but IF the Doppler was +200Hz and your station was +500Hz
        off, that would account for +700Hz. Doppler effect depends on the location
        of you and the other station. If your echo would have a Doppler of +200Hz
        and the other stations echo had a Doppler of -200Hz, then the QSO Doppler
        would be 0Hz. If this was the case, then your rig's frequency offset would
        have been +700Hz off. So it is hard to tell without knowing the circumstances.

        If you signal is getting through, the other station will locate you. JT65
        is in many ways like PSK31 but then again better. JT65 has the capability
        of searching over a +/- 400Hz range for your sync signal. Do not try to
        compensate for the Moon's Doppler effect. Just set your frequency so that
        their signal is in the center of SpecJT and let the other station find your
        signal. When the other station sees your sync signal, they will generally
        freeze their receive frequency on it and provide them with a better decode.
        Even if they don't, JT65 will search the tolerance range for a sync signal
        down to the noise level and attempt to decode it. The best operation you
        can do is make sure your PC time clock is matched with a time standard.

        The second best thing you can do is make sure your rig does not drift in
        frequency when transmitting. If Yaseu has a high stability option for the
        736, then get it. My Icom 746 has a bad drift and I had to build an oven
        for the crystal to fix it. I know that 2 stations both running barefoot
        IC-746 have a very hard time working each other even with AFC checked.

        I hope my answers help - if not ask away.

        73's and hope to catch you on the Moon.


        Lee Scott - AA1YN http://www.aa1yn.com
        Home of the VHF & Up Register http://www.aa1yn.com/vhf
        Home of the VHF Talk chatroom http://vhftalk.aa1yn.com
        Hooksett, NH
        FN43gc52
      • Paul Whatton
        Hi Enrico Congratulations on your QRP EME. I m also using a small station which is very similar to yours, a FT736R, 400 watts and a single 9 element F9FT. The
        Message 3 of 5 , Nov 13, 2006
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          Hi Enrico

          Congratulations on your QRP EME. I'm also using a small station which is
          very similar to yours, a FT736R, 400 watts and a single 9 element F9FT.
          The FT736R is very stable and works really well on WSJT. The FT-736R is
          much stabler than my second rig, an Icom 746.

          It sounds from what you sayt that your 736 calibration is 700Hz out.
          Mine is about 200Hz out, so I know when my display reads say, 144.130.2
          I am actually on 144.130. So just take your 700Hz error into account. Or
          even better if you have the workshop facilities you could re-calibrate
          your display.

          Having done that you know what frequency you are tuned to, but what
          about the doppler? On 2m it is only a maximum value of about 300Hz and
          most of the time much less than that if like me you use elevation. But
          it is nice to be close to the correct frequency and the doppler can be
          tricky to get your head around. Having said that, if there is a pileup,
          it's often better to call a bit off frequency!

          I don't pretend to be an expert and maybe someone will correct me if I'm
          wrong here. But this is what I figured out.

          If you have a sked then yes you are right, transmit on what you know to
          be the correct frequency and stay there. Then look for your sked partner
          to be shifted by his doppler. You won't need the RIT, his traces will
          just be offset away from the centre frequency in WSJT by the amount of
          his doppler plus/minus any error in his transmit frequency. That's fine.

          BTW. I've noticed that even some big guns are not always exactly on the
          frequency they say they will be :-) If (when) you find your sked partner
          is a long, long way off frequency then you have a dilemma. Should you
          stay where you are or should you move?

          But how about when you want to answer a CQ?

          Even with just a single 9 element the majority of QSOs I make are by
          calling someone. Either by tail ending or by answering their CQ call.
          Most are random, I usually don't tell them in N0UK or ON4KST that I'm
          going to call.

          Here's what I do. Let's say I hear a station calling CQ and when WSJT
          decodes him it indicates I am receiving him with a DF of +300Hz. But
          entering his locator tells me his doppler is actually say, -120Hz. So I
          retune the receiver to a frequency 420Hz higher. I should now get a DF
          of -120HZ on his decoded signal, the same figure as his predicted
          doppler shift. I then call him on that frequency. If I have it figured
          out correctly this will make my transmit frequency the same as his, and
          my received signal will be close to where he hears his own echos (all
          the stations I work will be able to hear their own echos).

          As an alternative, if you really want to use the RIT you can dial in the
          amount of the doppler and then aim to receive the other station with a
          DF of 0.

          I didn't have much time in the EME contest yesterday before I had to go
          out. But I called CQ and two stations called me who were both
          "off-channel" by about 100Hz more than I would have expected from their
          doppler. So don't worry about it too much, even the big EMEers are not
          always spot on frequency.

          73 Paul G4DCV

          Enrico - IZ0GYP wrote:
          >
          > Hi all,
          >
          > I'm a novice for EME (QRP with 9 element and 200W) and i'm still
          > studying the JT65B to be more familiar with the communication
          > procedures, trying to avoid mistakes and loose of time to the stations
          > that would reply to my skeds.
          > Up to now i succesfully completed 3 QSOs.
          >
          > Anyhow my problem is the following.
          >
          > If someone, on the EME chat, state a CQ call on 137 (144.137) this
          > means that both the calling station and the station that would like to
          > reply to his call shall have the VFO on 137,0 during TX.
          >
          > Now, i'm using a FT-736R and i'm almost sure about correctness of the
          > freq calibration.
          >
          > Usually a receive CQ station EME calls at SpecJT center when my VFO is
          > approx. 0,7 KHz higher (144.137,7).
          > Otherwise, leaving the VFO at 137,0 , i will see caller EME signals at
          > the far right side of the SpecJT screen (or even outside).
          > That's of course due to the Doppler effect but my concern is if 0,7
          > KHz is a standard frequency doppler shift on VHF or is a little bit
          > too big?
          > Due to my QRP conditions i can't receive my own echoes and the other
          > stations will see only light signals on their PCs.
          > I would like also to be sure at least that i'm not spending time
          > calling on a wrong frequency where the CQ caller station would never
          > receive me.
          >
          > Shall i therefore use the second FT-736 VFO on 0,7 KHz higher during
          > rx (FT-736R does not have independent RIT function)?
          >
          > Is my understanding correct that if i will be transmitting on the sked
          > frequency also my EME signals will be "falling" in the center part of
          > SpecJT screen of the other station (i guess that he will be also
          > listening 0,7 KHz higher)?
          >
          > Sorry if the questions may be appear probably confused (or even
          > terrible) to you but your help will be very appreciated on my side.
          >
          > Thanks for your kind reply and understandings
          >
          > Best 73's de Enrico - IZ0GYP
          >
          >
          > ------------------------------------------------------------------------
          >
          > No virus found in this incoming message.
          > Checked by AVG Free Edition.
          > Version: 7.5.430 / Virus Database: 268.14.3/531 - Release Date: 12/11/2006 19:34
          >
        • Jim Forsyth
          Enrico, Both of my 736s are off by about 100Hz on 144, more on the higher bands. On 2m I always set my VFO 100Hz low to compensate for the known error. The
          Message 4 of 5 , Nov 13, 2006
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            Enrico,

            Both of my 736s are off by about 100Hz on 144, more on the higher bands. On
            2m I always set my VFO 100Hz low to compensate for the known error. The
            other guy may be off frequency as well so between your error, his error and
            the Doppler it is possible to be off by quite a lot.

            You don't have to wonder about the Doppler shift because the JT65 screen
            tells you what the shift is between your grid and the grid that is entered
            for the other station (be sure you have the Band menu set correctly).

            To compensate for the Doppler on receive you can use the second VFO but it
            is easier to just press the CLAR button and tune the RX to where it needs to
            be.

            The +/- 600 Hz range of the WSJT software means you almost do not need to
            deal with the Doppler shift on 2m but on the higher bands it is essential.

            73 Jim, AF6O


            ----- Original Message -----
            From: Enrico - IZ0GYP
            To: wsjtgroup@yahoogroups.com
            Sent: Monday, November 13, 2006 12:58 AM
            Subject: [wsjtgroup] Sked and rx frequency - help and clarification


            Hi all,

            I'm a novice for EME (QRP with 9 element and 200W) and i'm still
            studying the JT65B to be more familiar with the communication
            procedures, trying to avoid mistakes and loose of time to the stations
            that would reply to my skeds.
            Up to now i succesfully completed 3 QSOs.

            Anyhow my problem is the following.

            If someone, on the EME chat, state a CQ call on 137 (144.137) this
            means that both the calling station and the station that would like to
            reply to his call shall have the VFO on 137,0 during TX.

            Now, i'm using a FT-736R and i'm almost sure about correctness of the
            freq calibration.

            Usually a receive CQ station EME calls at SpecJT center when my VFO is
            approx. 0,7 KHz higher (144.137,7).
            Otherwise, leaving the VFO at 137,0 , i will see caller EME signals at
            the far right side of the SpecJT screen (or even outside).
            That's of course due to the Doppler effect but my concern is if 0,7
            KHz is a standard frequency doppler shift on VHF or is a little bit
            too big?
            Due to my QRP conditions i can't receive my own echoes and the other
            stations will see only light signals on their PCs.
            I would like also to be sure at least that i'm not spending time
            calling on a wrong frequency where the CQ caller station would never
            receive me.

            Shall i therefore use the second FT-736 VFO on 0,7 KHz higher during
            rx (FT-736R does not have independent RIT function)?

            Is my understanding correct that if i will be transmitting on the sked
            frequency also my EME signals will be "falling" in the center part of
            SpecJT screen of the other station (i guess that he will be also
            listening 0,7 KHz higher)?

            Sorry if the questions may be appear probably confused (or even
            terrible) to you but your help will be very appreciated on my side.

            Thanks for your kind reply and understandings

            Best 73's de Enrico - IZ0GYP
          • Enrico - IZ0GYP
            Paul, once again my apologies to you and all the other friends that replied to my question. I have received and read your mails both on WSJT and direct to my
            Message 5 of 5 , Nov 18, 2006
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              Paul,

              once again my apologies to you and all the other friends that replied
              to my question.
              I have received and read your mails both on WSJT and direct to my
              private mail.
              Let me just inform you that i had sent my reply and thanks to all of
              you already on November 14th but i did probably an uncorrect
              operation while sending the answer back on the WSJT area.

              Therefore herebelow is the text that i wrote few days ago thanking
              all of you for the kind, prompt and precise support.

              - - - - - - - - - -

              Ok OM,

              thank you very much all of you for the appreciated suggestions.
              Due to the replies and to the emails received on my mail account i
              have understood very well principles, tecniques and i realized that
              my FT-736R would probably require a freq calibration.

              So thanks Jim (AF6O), Lee (AA1YN), John (W5UWB), Paul (G4DCV) and Don
              (KE7NR) for the valid support and CU all via the moon.

              Ciao

              Enrico - IZ0GYP


              - - - - - - - -

              So, once again, thanks and sorry if my post did not came through.

              I will be trying to call starting from tomorrow morning.

              Ciao e grazie

              Enrico



              --- In wsjtgroup@yahoogroups.com, Paul Whatton <paul@...> wrote:
              >
              > Hi Enrico
              >
              > Congratulations on your QRP EME. I'm also using a small station
              which is
              > very similar to yours, a FT736R, 400 watts and a single 9 element
              F9FT.
              > The FT736R is very stable and works really well on WSJT. The FT-
              736R is
              > much stabler than my second rig, an Icom 746.
              >
              > It sounds from what you sayt that your 736 calibration is 700Hz
              out.
              > Mine is about 200Hz out, so I know when my display reads say,
              144.130.2
              > I am actually on 144.130. So just take your 700Hz error into
              account. Or
              > even better if you have the workshop facilities you could re-
              calibrate
              > your display.
              >
              > Having done that you know what frequency you are tuned to, but what
              > about the doppler? On 2m it is only a maximum value of about 300Hz
              and
              > most of the time much less than that if like me you use elevation.
              But
              > it is nice to be close to the correct frequency and the doppler can
              be
              > tricky to get your head around. Having said that, if there is a
              pileup,
              > it's often better to call a bit off frequency!
              >
              > I don't pretend to be an expert and maybe someone will correct me
              if I'm
              > wrong here. But this is what I figured out.
              >
              > If you have a sked then yes you are right, transmit on what you
              know to
              > be the correct frequency and stay there. Then look for your sked
              partner
              > to be shifted by his doppler. You won't need the RIT, his traces
              will
              > just be offset away from the centre frequency in WSJT by the amount
              of
              > his doppler plus/minus any error in his transmit frequency. That's
              fine.
              >
              > BTW. I've noticed that even some big guns are not always exactly on
              the
              > frequency they say they will be :-) If (when) you find your sked
              partner
              > is a long, long way off frequency then you have a dilemma. Should
              you
              > stay where you are or should you move?
              >
              > But how about when you want to answer a CQ?
              >
              > Even with just a single 9 element the majority of QSOs I make are
              by
              > calling someone. Either by tail ending or by answering their CQ
              call.
              > Most are random, I usually don't tell them in N0UK or ON4KST that
              I'm
              > going to call.
              >
              > Here's what I do. Let's say I hear a station calling CQ and when
              WSJT
              > decodes him it indicates I am receiving him with a DF of +300Hz.
              But
              > entering his locator tells me his doppler is actually say, -120Hz.
              So I
              > retune the receiver to a frequency 420Hz higher. I should now get a
              DF
              > of -120HZ on his decoded signal, the same figure as his predicted
              > doppler shift. I then call him on that frequency. If I have it
              figured
              > out correctly this will make my transmit frequency the same as his,
              and
              > my received signal will be close to where he hears his own echos
              (all
              > the stations I work will be able to hear their own echos).
              >
              > As an alternative, if you really want to use the RIT you can dial
              in the
              > amount of the doppler and then aim to receive the other station
              with a
              > DF of 0.
              >
              > I didn't have much time in the EME contest yesterday before I had
              to go
              > out. But I called CQ and two stations called me who were both
              > "off-channel" by about 100Hz more than I would have expected from
              their
              > doppler. So don't worry about it too much, even the big EMEers are
              not
              > always spot on frequency.
              >
              > 73 Paul G4DCV
              >
              > Enrico - IZ0GYP wrote:
              > >
              > > Hi all,
              > >
              > > I'm a novice for EME (QRP with 9 element and 200W) and i'm still
              > > studying the JT65B to be more familiar with the communication
              > > procedures, trying to avoid mistakes and loose of time to the
              stations
              > > that would reply to my skeds.
              > > Up to now i succesfully completed 3 QSOs.
              > >
              > > Anyhow my problem is the following.
              > >
              > > If someone, on the EME chat, state a CQ call on 137 (144.137) this
              > > means that both the calling station and the station that would
              like to
              > > reply to his call shall have the VFO on 137,0 during TX.
              > >
              > > Now, i'm using a FT-736R and i'm almost sure about correctness of
              the
              > > freq calibration.
              > >
              > > Usually a receive CQ station EME calls at SpecJT center when my
              VFO is
              > > approx. 0,7 KHz higher (144.137,7).
              > > Otherwise, leaving the VFO at 137,0 , i will see caller EME
              signals at
              > > the far right side of the SpecJT screen (or even outside).
              > > That's of course due to the Doppler effect but my concern is if
              0,7
              > > KHz is a standard frequency doppler shift on VHF or is a little
              bit
              > > too big?
              > > Due to my QRP conditions i can't receive my own echoes and the
              other
              > > stations will see only light signals on their PCs.
              > > I would like also to be sure at least that i'm not spending time
              > > calling on a wrong frequency where the CQ caller station would
              never
              > > receive me.
              > >
              > > Shall i therefore use the second FT-736 VFO on 0,7 KHz higher
              during
              > > rx (FT-736R does not have independent RIT function)?
              > >
              > > Is my understanding correct that if i will be transmitting on the
              sked
              > > frequency also my EME signals will be "falling" in the center
              part of
              > > SpecJT screen of the other station (i guess that he will be also
              > > listening 0,7 KHz higher)?
              > >
              > > Sorry if the questions may be appear probably confused (or even
              > > terrible) to you but your help will be very appreciated on my
              side.
              > >
              > > Thanks for your kind reply and understandings
              > >
              > > Best 73's de Enrico - IZ0GYP
              > >
              > >
              > > ------------------------------------------------------------------
              ------
              > >
              > > No virus found in this incoming message.
              > > Checked by AVG Free Edition.
              > > Version: 7.5.430 / Virus Database: 268.14.3/531 - Release Date:
              12/11/2006 19:34
              > >
              >
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