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Re: [wsjtgroup] Sked and rx frequency - help and clarification

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  • 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 1 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 2 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 3 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 4 of 5 , Nov 18, 2006
          • 0 Attachment
            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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