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Re: [spectrumanalyzer] MO stability

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  • william sprowls
    Hi Jerry and All, First off, a precision 16 MHz source is a good choice as an option. Now, let me add a few cents on the subject of temperature compensation
    Message 1 of 17 , Aug 9, 2010
      Hi Jerry and All,
      First off, a precision 16 MHz source is a good choice as an option.
      Now, let me add a few cents on the subject of temperature compensation for Frequency and one cent for Phase.
      There are three components in the MSA/VNA that are susceptable to temperature changes:
      Master Oscillator - Frequency Change vs. Temp
      Coaxial Cavity Filter - Resonant Frequency Change vs. Temp (phase)
      Final Resolution Filter - Resonant Frequency Change vs. Temp (phase)
      All three have such a minor change in Magnitude vs. Temp, it is not even worth discussing (unless the Resolution Filter is extremely narrow).

      The Master Oscillator
       My original MSA concept did not have the VNA capability in mind. For Spectrum Analyzer and Tracking Generator operation, a minor amount of the Master Oscillator's Frequency drift is noticeable only if the Final Resolution Filter is extremely narrow (less than a few hundred Hz.). Of course, if the Tracking Generator is used as a Frequency Source, its frequency is dependent on the accuracy of the Master Oscillator. With a Master Oscillator stability of .15 ppm/1 deg F (9.6 Hz/1 deg F, as measured in the Verification MSA), this equates to a TG error of about 150 Hz / deg F.
       The Master Oscillator frequency of 64 MHz was chosen because this is a "standard" that is available from multiple sources. The present oscillator (Cash chose this one for price, availability, and stability) is a good one. With a little redesign of the SLIM-MO-64, it could be temperature compensated to much better than its .15 ppm/1 deg F.
       For those who wish to use a precision frequency source as a replacement to this oscillator, these are the requirements:
      A. Minimal requirement - 6 MHz to 100 MHz in 2 MHz increments (6,8,32,34,etc)
      B. Nominal requirement - 12 MHz to 100 MHz in 4 MHz increments
      1. For oscillator frequencies less than 22 MHz, the DDS's X4 multiplier can be utilized. The maximum division ratio in the DDS must be less than 2, due to Nyquist. Since the output of the DDS is appx. 10.7 MHz, its minimum clock must be greater than 21.4 MHz. Utilizing its X4 Multiplier, the minimum clock input must be greater than 21.4/4 or 5.35 MHz.
      2. PLO 2 uses the LMX 2326 pll and its minimum clock divider ratio is 3. Its phase/frequency detector should operate at a minimum of 2 MHz (4 MHz is optimal). Therefore, its minimum clock input (Master Oscillator) must be 6 MHz (12 MHz is preferred to obtain the 4 MHz PDF for PLO 2).
      3. The maximum frequency for the DDS is 128 MHz, but the maximum for the LMX 2326 is 100 MHz. Therefore, the Master Oscillator can not be greater than 100 MHz unless it is divided down.
      C. Optional Requirement. Requirements A and B assume the MSA's 2nd LO is 1024 MHz. However, this is not absolutely necessary. Any frequency between 1010 MHz and 1030 MHz could be used. It is possible to use almost any oscillator frequency between 6 and 100 MHz, but changes to the MSA software would need to be performed.

      For VNA operation, the Cavity Filter and Final Resolution Filters become the dominant phase drift factors for the MSA. If I had designed an MSA for utilization as a VNA only, I would not have used a Cavity Filter or "Resolution Filter". They are not necessary for VNA operation. In fact, the final filter would not be called a "Resolution Filter". It would just be called a noise limiting filter. A very simple single pole filter could replace the Cavity Filter, so could a resistive attenuator. Either would exhibit little or no phase drift over temperature. Same goes for a wide band final noise filter.

      To make a long story short, if you are extremely critical to Spectrum Analyzer frequency measurements, use a precision Master Oscillator. If you are critical for phase measurements in VNA mode, use a precision MO and modify the filter requirements for the First IF and Final IF.
       I added these comments on my Temperature Testing Web page for everyone to see.
      Scotty

      --- On Sat, 8/7/10, undercoupled <undercoupled@...> wrote:

      From: undercoupled <undercoupled@...>
      Subject: [spectrumanalyzer] MO stability
      To: spectrumanalyzer@yahoogroups.com
      Date: Saturday, August 7, 2010, 11:15 PM

       

      I am not familiar with what is available from Milliren, but have been looking for a more stable source of 64 MHz. My junk collection includes an ovenized, low phase noise 16 MHz source. I recently stumbled across some clock multipliers from IDT, carried by Digikey. The ICS670-01 operates from 5v, claims low phase noise, and can multiply by several different factors. Would these be useful in generating 64 MHz from a more available lower frequency standard?
      Jerry


    • nealmartini
      Scotty, Thanks for the writeup on alternatives for MO stability. I have been toying with the idea of adding an external reference oscillator input like those
      Message 2 of 17 , Aug 10, 2010
        Scotty,

        Thanks for the writeup on alternatives for MO stability. I have been toying with the idea of adding an external reference oscillator input like those that exist on most commercial spectrum analyzers.

        I can't locate it right now, but I think I recall you saying somewhere that we should avoid using the frequency multiplier feature in the AD9851. In fact, I think the data sheet even says something to that effect. Did you ever characterize the effect on phase noise in the PLLs if the multiplier was used?

        Also, Sam, is there one place in the code that I could change to activate the AD9851 multiplier?

        Neal


        --- In spectrumanalyzer@yahoogroups.com, william sprowls <wsprowls@...> wrote:
        >
        > Hi Jerry and All,
        > First off, a precision 16 MHz source is a good choice as an option.
        > Now, let me add a few cents on the subject of temperature compensation for Frequency and one cent for Phase.
        > There are three components in the MSA/VNA that are susceptable to temperature changes:
        > Master Oscillator - Frequency Change vs. Temp
        > Coaxial Cavity Filter - Resonant Frequency Change vs. Temp (phase)
        > Final Resolution Filter - Resonant Frequency Change vs. Temp (phase)
        > All three have such a minor change in Magnitude vs. Temp, it is not even worth discussing (unless the Resolution Filter is extremely narrow).
        >
        > The Master Oscillator
        >  My original MSA concept did not have the VNA capability in mind. For Spectrum Analyzer and Tracking Generator operation, a minor amount of the Master Oscillator's Frequency drift is noticeable only if the Final Resolution Filter is extremely narrow (less than a few hundred Hz.). Of course, if the Tracking Generator is used as a Frequency Source, its frequency is dependent on the accuracy of the Master Oscillator. With a Master Oscillator stability of .15 ppm/1 deg F (9.6 Hz/1 deg F, as measured in the Verification MSA), this equates to a TG error of about 150 Hz / deg F.
        >  The Master Oscillator frequency of 64 MHz was chosen because this is a "standard" that is available from multiple sources. The present oscillator (Cash chose this one for price, availability, and stability) is a good one. With a little redesign of the SLIM-MO-64, it could be temperature compensated to much better than its .15 ppm/1 deg F.
        >  For those who wish to use a precision frequency source as a replacement to this oscillator, these are the requirements:
        > A. Minimal requirement - 6 MHz to 100 MHz in 2 MHz increments (6,8,32,34,etc)
        > B. Nominal requirement - 12 MHz to 100 MHz in 4 MHz increments
        > 1. For oscillator frequencies less than 22 MHz, the DDS's X4 multiplier can be utilized. The maximum division ratio in the DDS must be less than 2, due to Nyquist. Since the output of the DDS is appx. 10.7 MHz, its minimum clock must be greater than 21.4 MHz. Utilizing its X4 Multiplier, the minimum clock input must be greater than 21.4/4 or 5.35 MHz.
        > 2. PLO 2 uses the LMX 2326 pll and its minimum clock divider ratio is 3. Its phase/frequency detector should operate at a minimum of 2 MHz (4 MHz is optimal). Therefore, its minimum clock input (Master Oscillator) must be 6 MHz (12 MHz is preferred to obtain the 4 MHz PDF for PLO 2).
        > 3. The maximum frequency for the DDS is 128 MHz, but the maximum for the LMX 2326 is 100 MHz. Therefore, the Master Oscillator can not be greater than 100 MHz unless it is divided down.
        > C. Optional Requirement. Requirements A and B assume the MSA's 2nd LO is 1024 MHz. However, this is not absolutely necessary. Any frequency between 1010 MHz and 1030 MHz could be used. It is possible to use almost any oscillator frequency between 6 and 100 MHz, but changes to the MSA software would need to be performed.
        >
        > For VNA operation, the Cavity Filter and Final Resolution Filters become the dominant phase drift factors for the MSA. If I had designed an MSA for utilization as a VNA only, I would not have used a Cavity Filter or "Resolution Filter". They are not necessary for VNA operation. In fact, the final filter would not be called a "Resolution Filter". It would just be called a noise limiting filter. A very simple single pole filter could replace the Cavity Filter, so could a resistive attenuator. Either would exhibit little or no phase drift over temperature. Same goes for a wide band final noise filter.
        >
        > To make a long story short, if you are extremely critical to Spectrum Analyzer frequency measurements, use a precision Master Oscillator. If you are critical for phase measurements in VNA mode, use a precision MO and modify the filter requirements for the First IF and Final IF.
        >  I added these comments on my Temperature Testing Web page for everyone to see.
        > Scotty
        >
        > --- On Sat, 8/7/10, undercoupled <undercoupled@...> wrote:
        >
        > From: undercoupled <undercoupled@...>
        > Subject: [spectrumanalyzer] MO stability
        > To: spectrumanalyzer@yahoogroups.com
        > Date: Saturday, August 7, 2010, 11:15 PM
        >
        >
        >
        >
        >
        >
        >
        >  
        >
        >
        >
        >
        >
        >
        >
        >
        >
        > I am not familiar with what is available from Milliren, but have been looking for a more stable source of 64 MHz. My junk collection includes an ovenized, low phase noise 16 MHz source. I recently stumbled across some clock multipliers from IDT, carried by Digikey. The ICS670-01 operates from 5v, claims low phase noise, and can multiply by several different factors. Would these be useful in generating 64 MHz from a more available lower frequency standard?
        >
        > Jerry
        >
      • Sam
        Neal, This is the line you are looking for: w0= 0 a 1 here will activate the x4 internal multiplier, but not recommended Sam W.
        Message 3 of 17 , Aug 10, 2010
          Neal,
          This is the line you are looking for:

          w0= 0 'a "1" here will activate the x4 internal multiplier, but not recommended

          Sam W.

          --- In spectrumanalyzer@yahoogroups.com, "nealmartini" <nealmartini@...> wrote:
          >
          > Scotty,
          >
          > Thanks for the writeup on alternatives for MO stability. I have been toying with the idea of adding an external reference oscillator input like those that exist on most commercial spectrum analyzers.
          >
          > I can't locate it right now, but I think I recall you saying somewhere that we should avoid using the frequency multiplier feature in the AD9851. In fact, I think the data sheet even says something to that effect. Did you ever characterize the effect on phase noise in the PLLs if the multiplier was used?
          >
          > Also, Sam, is there one place in the code that I could change to activate the AD9851 multiplier?
          >
          > Neal
          >
          >
          > --- In spectrumanalyzer@yahoogroups.com, william sprowls <wsprowls@> wrote:
          > >
          > > Hi Jerry and All,
          > > First off, a precision 16 MHz source is a good choice as an option.
          > > Now, let me add a few cents on the subject of temperature compensation for Frequency and one cent for Phase.
          > > There are three components in the MSA/VNA that are susceptable to temperature changes:
          > > Master Oscillator - Frequency Change vs. Temp
          > > Coaxial Cavity Filter - Resonant Frequency Change vs. Temp (phase)
          > > Final Resolution Filter - Resonant Frequency Change vs. Temp (phase)
          > > All three have such a minor change in Magnitude vs. Temp, it is not even worth discussing (unless the Resolution Filter is extremely narrow).
          > >
          > > The Master Oscillator
          > >  My original MSA concept did not have the VNA capability in mind. For Spectrum Analyzer and Tracking Generator operation, a minor amount of the Master Oscillator's Frequency drift is noticeable only if the Final Resolution Filter is extremely narrow (less than a few hundred Hz.). Of course, if the Tracking Generator is used as a Frequency Source, its frequency is dependent on the accuracy of the Master Oscillator. With a Master Oscillator stability of .15 ppm/1 deg F (9.6 Hz/1 deg F, as measured in the Verification MSA), this equates to a TG error of about 150 Hz / deg F.
          > >  The Master Oscillator frequency of 64 MHz was chosen because this is a "standard" that is available from multiple sources. The present oscillator (Cash chose this one for price, availability, and stability) is a good one. With a little redesign of the SLIM-MO-64, it could be temperature compensated to much better than its .15 ppm/1 deg F.
          > >  For those who wish to use a precision frequency source as a replacement to this oscillator, these are the requirements:
          > > A. Minimal requirement - 6 MHz to 100 MHz in 2 MHz increments (6,8,32,34,etc)
          > > B. Nominal requirement - 12 MHz to 100 MHz in 4 MHz increments
          > > 1. For oscillator frequencies less than 22 MHz, the DDS's X4 multiplier can be utilized. The maximum division ratio in the DDS must be less than 2, due to Nyquist. Since the output of the DDS is appx. 10.7 MHz, its minimum clock must be greater than 21.4 MHz. Utilizing its X4 Multiplier, the minimum clock input must be greater than 21.4/4 or 5.35 MHz.
          > > 2. PLO 2 uses the LMX 2326 pll and its minimum clock divider ratio is 3. Its phase/frequency detector should operate at a minimum of 2 MHz (4 MHz is optimal). Therefore, its minimum clock input (Master Oscillator) must be 6 MHz (12 MHz is preferred to obtain the 4 MHz PDF for PLO 2).
          > > 3. The maximum frequency for the DDS is 128 MHz, but the maximum for the LMX 2326 is 100 MHz. Therefore, the Master Oscillator can not be greater than 100 MHz unless it is divided down.
          > > C. Optional Requirement. Requirements A and B assume the MSA's 2nd LO is 1024 MHz. However, this is not absolutely necessary. Any frequency between 1010 MHz and 1030 MHz could be used. It is possible to use almost any oscillator frequency between 6 and 100 MHz, but changes to the MSA software would need to be performed.
          > >
          > > For VNA operation, the Cavity Filter and Final Resolution Filters become the dominant phase drift factors for the MSA. If I had designed an MSA for utilization as a VNA only, I would not have used a Cavity Filter or "Resolution Filter". They are not necessary for VNA operation. In fact, the final filter would not be called a "Resolution Filter". It would just be called a noise limiting filter. A very simple single pole filter could replace the Cavity Filter, so could a resistive attenuator. Either would exhibit little or no phase drift over temperature. Same goes for a wide band final noise filter.
          > >
          > > To make a long story short, if you are extremely critical to Spectrum Analyzer frequency measurements, use a precision Master Oscillator. If you are critical for phase measurements in VNA mode, use a precision MO and modify the filter requirements for the First IF and Final IF.
          > >  I added these comments on my Temperature Testing Web page for everyone to see.
          > > Scotty
          > >
          > > --- On Sat, 8/7/10, undercoupled <undercoupled@> wrote:
          > >
          > > From: undercoupled <undercoupled@>
          > > Subject: [spectrumanalyzer] MO stability
          > > To: spectrumanalyzer@yahoogroups.com
          > > Date: Saturday, August 7, 2010, 11:15 PM
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >  
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > >
          > > I am not familiar with what is available from Milliren, but have been looking for a more stable source of 64 MHz. My junk collection includes an ovenized, low phase noise 16 MHz source. I recently stumbled across some clock multipliers from IDT, carried by Digikey. The ICS670-01 operates from 5v, claims low phase noise, and can multiply by several different factors. Would these be useful in generating 64 MHz from a more available lower frequency standard?
          > >
          > > Jerry
          > >
          >
        • william sprowls
          Hi Neal,  The multiplier function is in the code, but not accessable thru the Manager Windows. It could be, however. I did do some testing with the X4
          Message 4 of 17 , Aug 10, 2010
            Hi Neal,
             The multiplier function is in the code, but not accessable thru the Manager Windows. It could be, however.
            I did do some testing with the X4 multiplier of the 9850. It is supposed to increase its phase noise, but we can't see the affect in the MSA because the base phase noise of PLO 1 dominates and covers it up.
            Scotty

            --- On Tue, 8/10/10, nealmartini <nealmartini@...> wrote:

            From: nealmartini <nealmartini@...>
            Subject: [spectrumanalyzer] Re: MO stability
            To: spectrumanalyzer@yahoogroups.com
            Date: Tuesday, August 10, 2010, 10:03 AM

             

            Scotty,

            Thanks for the writeup on alternatives for MO stability. I have been toying with the idea of adding an external reference oscillator input like those that exist on most commercial spectrum analyzers.

            I can't locate it right now, but I think I recall you saying somewhere that we should avoid using the frequency multiplier feature in the AD9851. In fact, I think the data sheet even says something to that effect. Did you ever characterize the effect on phase noise in the PLLs if the multiplier was used?

            Also, Sam, is there one place in the code that I could change to activate the AD9851 multiplier?

            Neal

            --- In spectrumanalyzer@yahoogroups.com, william sprowls <wsprowls@...> wrote:
            >
            > Hi Jerry and All,
            > First off, a precision 16 MHz source is a good choice as an option.
            > Now, let me add a few cents on the subject of temperature compensation for Frequency and one cent for Phase.
            > There are three components in the MSA/VNA that are susceptable to temperature changes:
            > Master Oscillator - Frequency Change vs. Temp
            > Coaxial Cavity Filter - Resonant Frequency Change vs. Temp (phase)
            > Final Resolution Filter - Resonant Frequency Change vs. Temp (phase)
            > All three have such a minor change in Magnitude vs. Temp, it is not even worth discussing (unless the Resolution Filter is extremely narrow).
            >
            > The Master Oscillator
            > Â My original MSA concept did not have the VNA capability in mind. For Spectrum Analyzer and Tracking Generator operation, a minor amount of the Master Oscillator's Frequency drift is noticeable only if the Final Resolution Filter is extremely narrow (less than a few hundred Hz.). Of course, if the Tracking Generator is used as a Frequency Source, its frequency is dependent on the accuracy of the Master Oscillator. With a Master Oscillator stability of .15 ppm/1 deg F (9.6 Hz/1 deg F, as measured in the Verification MSA), this equates to a TG error of about 150 Hz / deg F.
            > Â The Master Oscillator frequency of 64 MHz was chosen because this is a "standard" that is available from multiple sources. The present oscillator (Cash chose this one for price, availability, and stability) is a good one. With a little redesign of the SLIM-MO-64, it could be temperature compensated to much better than its .15 ppm/1 deg F.
            > Â For those who wish to use a precision frequency source as a replacement to this oscillator, these are the requirements:
            > A. Minimal requirement - 6 MHz to 100 MHz in 2 MHz increments (6,8,32,34,etc)
            > B. Nominal requirement - 12 MHz to 100 MHz in 4 MHz increments
            > 1. For oscillator frequencies less than 22 MHz, the DDS's X4 multiplier can be utilized. The maximum division ratio in the DDS must be less than 2, due to Nyquist. Since the output of the DDS is appx. 10.7 MHz, its minimum clock must be greater than 21.4 MHz. Utilizing its X4 Multiplier, the minimum clock input must be greater than 21.4/4 or 5.35 MHz.
            > 2. PLO 2 uses the LMX 2326 pll and its minimum clock divider ratio is 3. Its phase/frequency detector should operate at a minimum of 2 MHz (4 MHz is optimal). Therefore, its minimum clock input (Master Oscillator) must be 6 MHz (12 MHz is preferred to obtain the 4 MHz PDF for PLO 2).
            > 3. The maximum frequency for the DDS is 128 MHz, but the maximum for the LMX 2326 is 100 MHz. Therefore, the Master Oscillator can not be greater than 100 MHz unless it is divided down.
            > C. Optional Requirement. Requirements A and B assume the MSA's 2nd LO is 1024 MHz. However, this is not absolutely necessary. Any frequency between 1010 MHz and 1030 MHz could be used. It is possible to use almost any oscillator frequency between 6 and 100 MHz, but changes to the MSA software would need to be performed.
            >
            > For VNA operation, the Cavity Filter and Final Resolution Filters become the dominant phase drift factors for the MSA. If I had designed an MSA for utilization as a VNA only, I would not have used a Cavity Filter or "Resolution Filter". They are not necessary for VNA operation. In fact, the final filter would not be called a "Resolution Filter". It would just be called a noise limiting filter. A very simple single pole filter could replace the Cavity Filter, so could a resistive attenuator. Either would exhibit little or no phase drift over temperature. Same goes for a wide band final noise filter.
            >
            > To make a long story short, if you are extremely critical to Spectrum Analyzer frequency measurements, use a precision Master Oscillator. If you are critical for phase measurements in VNA mode, use a precision MO and modify the filter requirements for the First IF and Final IF.
            > Â I added these comments on my Temperature Testing Web page for everyone to see.
            > Scotty
            >
            > --- On Sat, 8/7/10, undercoupled <undercoupled@...> wrote:
            >
            > From: undercoupled <undercoupled@...>
            > Subject: [spectrumanalyzer] MO stability
            > To: spectrumanalyzer@yahoogroups.com
            > Date: Saturday, August 7, 2010, 11:15 PM
            >
            >
            >
            >
            >
            >
            >
            > Â
            >
            >
            >
            >
            >
            >
            >
            >
            >
            > I am not familiar with what is available from Milliren, but have been looking for a more stable source of 64 MHz. My junk collection includes an ovenized, low phase noise 16 MHz source. I recently stumbled across some clock multipliers from IDT, carried by Digikey. The ICS670-01 operates from 5v, claims low phase noise, and can multiply by several different factors. Would these be useful in generating 64 MHz from a more available lower frequency standard?
            >
            > Jerry
            >


          • Sam
            A simple way to do the code would be to use the multiplier if the clock is below 21.4 MHz. Anything below that would have to use the multiplier, and I don t
            Message 5 of 17 , Aug 10, 2010
              A simple way to do the code would be to use the multiplier if the clock is below 21.4 MHz. Anything below that would have to use the multiplier, and I don't think anyone would be using a precision reference above that and still want to use the multiplier.

              I looked through eBay and 90% of the precision references are 10 MHz. If you use the x4 multiplier so you get a DDS clock of 40 MHz, do you get higher spur levels at 10.7 MHz output than you would at 64 MHz?

              Here would be an interesting source to use with the x4 multipler:

              <http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=300304396557&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en>

              It is roughly 19.45 MHz, relatively small, runs off 12V (24V is more typical) and has good specs. Not as good as Rubidium, but very nice, especially for its size and $21 cost (includes shipping). Apparently, many are available. Temp stability of 20 ppb over a very broad temp range. One year aging of 0.1 ppm.

              Sam W.


              --- In spectrumanalyzer@yahoogroups.com, william sprowls <wsprowls@...> wrote:
              >
              > Hi Neal,
              >  The multiplier function is in the code, but not accessable thru the Manager Windows. It could be, however.
              > I did do some testing with the X4 multiplier of the 9850. It is supposed to increase its phase noise, but we can't see the affect in the MSA because the base phase noise of PLO 1 dominates and covers it up.
              > Scotty
              >
              > --- On Tue, 8/10/10, nealmartini <nealmartini@...> wrote:
              >
              > From: nealmartini <nealmartini@...>
              > Subject: [spectrumanalyzer] Re: MO stability
              > To: spectrumanalyzer@yahoogroups.com
              > Date: Tuesday, August 10, 2010, 10:03 AM
              >
              >
              >
              >
              >
              >
              >
              >  
              >
              >
              >
              >
              >
              >
              >
              >
              >
              > Scotty,
              >
              >
              >
              > Thanks for the writeup on alternatives for MO stability. I have been toying with the idea of adding an external reference oscillator input like those that exist on most commercial spectrum analyzers.
              >
              >
              >
              > I can't locate it right now, but I think I recall you saying somewhere that we should avoid using the frequency multiplier feature in the AD9851. In fact, I think the data sheet even says something to that effect. Did you ever characterize the effect on phase noise in the PLLs if the multiplier was used?
              >
              >
              >
              > Also, Sam, is there one place in the code that I could change to activate the AD9851 multiplier?
              >
              >
              >
              > Neal
              >
              >
              >
              > --- In spectrumanalyzer@yahoogroups.com, william sprowls <wsprowls@> wrote:
              >
              > >
              >
              > > Hi Jerry and All,
              >
              > > First off, a precision 16 MHz source is a good choice as an option.
              >
              > > Now, let me add a few cents on the subject of temperature compensation for Frequency and one cent for Phase.
              >
              > > There are three components in the MSA/VNA that are susceptable to temperature changes:
              >
              > > Master Oscillator - Frequency Change vs. Temp
              >
              > > Coaxial Cavity Filter - Resonant Frequency Change vs. Temp (phase)
              >
              > > Final Resolution Filter - Resonant Frequency Change vs. Temp (phase)
              >
              > > All three have such a minor change in Magnitude vs. Temp, it is not even worth discussing (unless the Resolution Filter is extremely narrow).
              >
              > >
              >
              > > The Master Oscillator
              >
              > > Â My original MSA concept did not have the VNA capability in mind. For Spectrum Analyzer and Tracking Generator operation, a minor amount of the Master Oscillator's Frequency drift is noticeable only if the Final Resolution Filter is extremely narrow (less than a few hundred Hz.). Of course, if the Tracking Generator is used as a Frequency Source, its frequency is dependent on the accuracy of the Master Oscillator. With a Master Oscillator stability of .15 ppm/1 deg F (9.6 Hz/1 deg F, as measured in the Verification MSA), this equates to a TG error of about 150 Hz / deg F.
              >
              > > Â The Master Oscillator frequency of 64 MHz was chosen because this is a "standard" that is available from multiple sources. The present oscillator (Cash chose this one for price, availability, and stability) is a good one. With a little redesign of the SLIM-MO-64, it could be temperature compensated to much better than its .15 ppm/1 deg F.
              >
              > > Â For those who wish to use a precision frequency source as a replacement to this oscillator, these are the requirements:
              >
              > > A. Minimal requirement - 6 MHz to 100 MHz in 2 MHz increments (6,8,32,34,etc)
              >
              > > B. Nominal requirement - 12 MHz to 100 MHz in 4 MHz increments
              >
              > > 1. For oscillator frequencies less than 22 MHz, the DDS's X4 multiplier can be utilized. The maximum division ratio in the DDS must be less than 2, due to Nyquist. Since the output of the DDS is appx. 10.7 MHz, its minimum clock must be greater than 21.4 MHz. Utilizing its X4 Multiplier, the minimum clock input must be greater than 21.4/4 or 5.35 MHz.
              >
              > > 2. PLO 2 uses the LMX 2326 pll and its minimum clock divider ratio is 3. Its phase/frequency detector should operate at a minimum of 2 MHz (4 MHz is optimal). Therefore, its minimum clock input (Master Oscillator) must be 6 MHz (12 MHz is preferred to obtain the 4 MHz PDF for PLO 2).
              >
              > > 3. The maximum frequency for the DDS is 128 MHz, but the maximum for the LMX 2326 is 100 MHz. Therefore, the Master Oscillator can not be greater than 100 MHz unless it is divided down.
              >
              > > C. Optional Requirement. Requirements A and B assume the MSA's 2nd LO is 1024 MHz. However, this is not absolutely necessary. Any frequency between 1010 MHz and 1030 MHz could be used. It is possible to use almost any oscillator frequency between 6 and 100 MHz, but changes to the MSA software would need to be performed.
              >
              > >
              >
              > > For VNA operation, the Cavity Filter and Final Resolution Filters become the dominant phase drift factors for the MSA. If I had designed an MSA for utilization as a VNA only, I would not have used a Cavity Filter or "Resolution Filter". They are not necessary for VNA operation. In fact, the final filter would not be called a "Resolution Filter". It would just be called a noise limiting filter. A very simple single pole filter could replace the Cavity Filter, so could a resistive attenuator. Either would exhibit little or no phase drift over temperature. Same goes for a wide band final noise filter.
              >
              > >
              >
              > > To make a long story short, if you are extremely critical to Spectrum Analyzer frequency measurements, use a precision Master Oscillator. If you are critical for phase measurements in VNA mode, use a precision MO and modify the filter requirements for the First IF and Final IF.
              >
              > > Â I added these comments on my Temperature Testing Web page for everyone to see.
              >
              > > Scotty
              >
              > >
              >
              > > --- On Sat, 8/7/10, undercoupled <undercoupled@> wrote:
              >
              > >
              >
              > > From: undercoupled <undercoupled@>
              >
              > > Subject: [spectrumanalyzer] MO stability
              >
              > > To: spectrumanalyzer@yahoogroups.com
              >
              > > Date: Saturday, August 7, 2010, 11:15 PM
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > > Â
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > >
              >
              > > I am not familiar with what is available from Milliren, but have been looking for a more stable source of 64 MHz. My junk collection includes an ovenized, low phase noise 16 MHz source. I recently stumbled across some clock multipliers from IDT, carried by Digikey. The ICS670-01 operates from 5v, claims low phase noise, and can multiply by several different factors. Would these be useful in generating 64 MHz from a more available lower frequency standard?
              >
              > >
              >
              > > Jerry
              >
              > >
              >
            • nealmartini
              Scotty, How did you come up with the MO spec of .15 ppm/ deg F? I can t find it on the clock data sheet. Neal
              Message 6 of 17 , Aug 11, 2010
                Scotty,

                How did you come up with the MO spec of .15 ppm/ deg F? I can't find it on the clock data sheet.

                Neal





                --- In spectrumanalyzer@yahoogroups.com, william sprowls <wsprowls@...> wrote:
                >
                > Hi Jerry and All,
                > First off, a precision 16 MHz source is a good choice as an option.
                > Now, let me add a few cents on the subject of temperature compensation for Frequency and one cent for Phase.
                > There are three components in the MSA/VNA that are susceptable to temperature changes:
                > Master Oscillator - Frequency Change vs. Temp
                > Coaxial Cavity Filter - Resonant Frequency Change vs. Temp (phase)
                > Final Resolution Filter - Resonant Frequency Change vs. Temp (phase)
                > All three have such a minor change in Magnitude vs. Temp, it is not even worth discussing (unless the Resolution Filter is extremely narrow).
                >
                > The Master Oscillator
                >  My original MSA concept did not have the VNA capability in mind. For Spectrum Analyzer and Tracking Generator operation, a minor amount of the Master Oscillator's Frequency drift is noticeable only if the Final Resolution Filter is extremely narrow (less than a few hundred Hz.). Of course, if the Tracking Generator is used as a Frequency Source, its frequency is dependent on the accuracy of the Master Oscillator. With a Master Oscillator stability of .15 ppm/1 deg F (9.6 Hz/1 deg F, as measured in the Verification MSA), this equates to a TG error of about 150 Hz / deg F.
                >  The Master Oscillator frequency of 64 MHz was chosen because this is a "standard" that is available from multiple sources. The present oscillator (Cash chose this one for price, availability, and stability) is a good one. With a little redesign of the SLIM-MO-64, it could be temperature compensated to much better than its .15 ppm/1 deg F.
                >  For those who wish to use a precision frequency source as a replacement to this oscillator, these are the requirements:
                > A. Minimal requirement - 6 MHz to 100 MHz in 2 MHz increments (6,8,32,34,etc)
                > B. Nominal requirement - 12 MHz to 100 MHz in 4 MHz increments
                > 1. For oscillator frequencies less than 22 MHz, the DDS's X4 multiplier can be utilized. The maximum division ratio in the DDS must be less than 2, due to Nyquist. Since the output of the DDS is appx. 10.7 MHz, its minimum clock must be greater than 21.4 MHz. Utilizing its X4 Multiplier, the minimum clock input must be greater than 21.4/4 or 5.35 MHz.
                > 2. PLO 2 uses the LMX 2326 pll and its minimum clock divider ratio is 3. Its phase/frequency detector should operate at a minimum of 2 MHz (4 MHz is optimal). Therefore, its minimum clock input (Master Oscillator) must be 6 MHz (12 MHz is preferred to obtain the 4 MHz PDF for PLO 2).
                > 3. The maximum frequency for the DDS is 128 MHz, but the maximum for the LMX 2326 is 100 MHz. Therefore, the Master Oscillator can not be greater than 100 MHz unless it is divided down.
                > C. Optional Requirement. Requirements A and B assume the MSA's 2nd LO is 1024 MHz. However, this is not absolutely necessary. Any frequency between 1010 MHz and 1030 MHz could be used. It is possible to use almost any oscillator frequency between 6 and 100 MHz, but changes to the MSA software would need to be performed.
                >
                > For VNA operation, the Cavity Filter and Final Resolution Filters become the dominant phase drift factors for the MSA. If I had designed an MSA for utilization as a VNA only, I would not have used a Cavity Filter or "Resolution Filter". They are not necessary for VNA operation. In fact, the final filter would not be called a "Resolution Filter". It would just be called a noise limiting filter. A very simple single pole filter could replace the Cavity Filter, so could a resistive attenuator. Either would exhibit little or no phase drift over temperature. Same goes for a wide band final noise filter.
                >
                > To make a long story short, if you are extremely critical to Spectrum Analyzer frequency measurements, use a precision Master Oscillator. If you are critical for phase measurements in VNA mode, use a precision MO and modify the filter requirements for the First IF and Final IF.
                >  I added these comments on my Temperature Testing Web page for everyone to see.
                > Scotty
                >
                > --- On Sat, 8/7/10, undercoupled <undercoupled@...> wrote:
                >
                > From: undercoupled <undercoupled@...>
                > Subject: [spectrumanalyzer] MO stability
                > To: spectrumanalyzer@yahoogroups.com
                > Date: Saturday, August 7, 2010, 11:15 PM
                >
                >
                >
                >
                >
                >
                >
                >  
                >
                >
                >
                >
                >
                >
                >
                >
                >
                > I am not familiar with what is available from Milliren, but have been looking for a more stable source of 64 MHz. My junk collection includes an ovenized, low phase noise 16 MHz source. I recently stumbled across some clock multipliers from IDT, carried by Digikey. The ICS670-01 operates from 5v, claims low phase noise, and can multiply by several different factors. Would these be useful in generating 64 MHz from a more available lower frequency standard?
                >
                > Jerry
                >
              • william sprowls
                Hi Neal, Correct, it isn t there. This was measured on the bench, using a sample of one. Scotty ... From: nealmartini Subject:
                Message 7 of 17 , Aug 11, 2010
                  Hi Neal,
                  Correct, it isn't there. This was measured on the bench, using a sample of one.
                  Scotty

                  --- On Wed, 8/11/10, nealmartini <nealmartini@...> wrote:

                  From: nealmartini <nealmartini@...>
                  Subject: [spectrumanalyzer] Re: MO stability
                  To: spectrumanalyzer@yahoogroups.com
                  Date: Wednesday, August 11, 2010, 10:39 AM

                   

                  Scotty,

                  How did you come up with the MO spec of .15 ppm/ deg F? I can't find it on the clock data sheet.

                  Neal

                  --- In spectrumanalyzer@yahoogroups.com, william sprowls <wsprowls@...> wrote:
                  >
                  > Hi Jerry and All,
                  > First off, a precision 16 MHz source is a good choice as an option.
                  > Now, let me add a few cents on the subject of temperature compensation for Frequency and one cent for Phase.
                  > There are three components in the MSA/VNA that are susceptable to temperature changes:
                  > Master Oscillator - Frequency Change vs. Temp
                  > Coaxial Cavity Filter - Resonant Frequency Change vs. Temp (phase)
                  > Final Resolution Filter - Resonant Frequency Change vs. Temp (phase)
                  > All three have such a minor change in Magnitude vs. Temp, it is not even worth discussing (unless the Resolution Filter is extremely narrow).
                  >
                  > The Master Oscillator
                  > Â My original MSA concept did not have the VNA capability in mind. For Spectrum Analyzer and Tracking Generator operation, a minor amount of the Master Oscillator's Frequency drift is noticeable only if the Final Resolution Filter is extremely narrow (less than a few hundred Hz.). Of course, if the Tracking Generator is used as a Frequency Source, its frequency is dependent on the accuracy of the Master Oscillator. With a Master Oscillator stability of .15 ppm/1 deg F (9.6 Hz/1 deg F, as measured in the Verification MSA), this equates to a TG error of about 150 Hz / deg F.
                  > Â The Master Oscillator frequency of 64 MHz was chosen because this is a "standard" that is available from multiple sources. The present oscillator (Cash chose this one for price, availability, and stability) is a good one. With a little redesign of the SLIM-MO-64, it could be temperature compensated to much better than its .15 ppm/1 deg F.
                  > Â For those who wish to use a precision frequency source as a replacement to this oscillator, these are the requirements:
                  > A. Minimal requirement - 6 MHz to 100 MHz in 2 MHz increments (6,8,32,34,etc)
                  > B. Nominal requirement - 12 MHz to 100 MHz in 4 MHz increments
                  > 1. For oscillator frequencies less than 22 MHz, the DDS's X4 multiplier can be utilized. The maximum division ratio in the DDS must be less than 2, due to Nyquist. Since the output of the DDS is appx. 10.7 MHz, its minimum clock must be greater than 21.4 MHz. Utilizing its X4 Multiplier, the minimum clock input must be greater than 21.4/4 or 5.35 MHz.
                  > 2. PLO 2 uses the LMX 2326 pll and its minimum clock divider ratio is 3. Its phase/frequency detector should operate at a minimum of 2 MHz (4 MHz is optimal). Therefore, its minimum clock input (Master Oscillator) must be 6 MHz (12 MHz is preferred to obtain the 4 MHz PDF for PLO 2).
                  > 3. The maximum frequency for the DDS is 128 MHz, but the maximum for the LMX 2326 is 100 MHz. Therefore, the Master Oscillator can not be greater than 100 MHz unless it is divided down.
                  > C. Optional Requirement. Requirements A and B assume the MSA's 2nd LO is 1024 MHz. However, this is not absolutely necessary. Any frequency between 1010 MHz and 1030 MHz could be used. It is possible to use almost any oscillator frequency between 6 and 100 MHz, but changes to the MSA software would need to be performed.
                  >
                  > For VNA operation, the Cavity Filter and Final Resolution Filters become the dominant phase drift factors for the MSA. If I had designed an MSA for utilization as a VNA only, I would not have used a Cavity Filter or "Resolution Filter". They are not necessary for VNA operation. In fact, the final filter would not be called a "Resolution Filter". It would just be called a noise limiting filter. A very simple single pole filter could replace the Cavity Filter, so could a resistive attenuator. Either would exhibit little or no phase drift over temperature. Same goes for a wide band final noise filter.
                  >
                  > To make a long story short, if you are extremely critical to Spectrum Analyzer frequency measurements, use a precision Master Oscillator. If you are critical for phase measurements in VNA mode, use a precision MO and modify the filter requirements for the First IF and Final IF.
                  > Â I added these comments on my Temperature Testing Web page for everyone to see.
                  > Scotty
                  >
                  > --- On Sat, 8/7/10, undercoupled <undercoupled@...> wrote:
                  >
                  > From: undercoupled <undercoupled@...>
                  > Subject: [spectrumanalyzer] MO stability
                  > To: spectrumanalyzer@yahoogroups.com
                  > Date: Saturday, August 7, 2010, 11:15 PM
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  > Â
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  > I am not familiar with what is available from Milliren, but have been looking for a more stable source of 64 MHz. My junk collection includes an ovenized, low phase noise 16 MHz source. I recently stumbled across some clock multipliers from IDT, carried by Digikey. The ICS670-01 operates from 5v, claims low phase noise, and can multiply by several different factors. Would these be useful in generating 64 MHz from a more available lower frequency standard?
                  >
                  > Jerry
                  >


                • Ron
                  MO stability is a subject that I am quite interested in. My MSA is to the final firing up stage. All coming together nicely. Working on the RBW filters at
                  Message 8 of 17 , Aug 11, 2010
                    MO stability is a subject that I am quite interested in.
                    My MSA is to the final firing up stage. All coming together nicely.
                    Working on the RBW filters at present then I'll come back to the MO.
                    My aim is to lock the MO to my GPS disciplined oscillator. Stability will then be a non issue.
                    A couple of years ago I built a GPS disciplined oscillator based on the design by James Miller, G3RUH. Google will find it for you. I used a 13 MHz OCXO. Works brilliantly. It outputs a 1 MHz reference signal. I then built a DDS oscillator and frequency counter. Google "S53MV DDS" and you will find them. Brilliant devices. I then phased locked the frequency counter to the GPS disciplined oscillator. The VCXO I used in the counter can be found as eBay item 160437166617. Plenty more available.
                    These are a very nice TC-VCXO and worth considering for a 10 MHz oscillator. If I was building the GPS oscillator again I would try using this device instead of the 13 MHz OCXO.
                    But I had trouble finding a suitable VCXO to phase lock the DDS oscillator. I eventually found eBay item 350271667341, a 32 MHz Murata VCXO. I am yet to incorporate this into the DDS oscillator because at this stage I started working on the MSA. I then realised that this Murata VCXO might be suitable for phase locking the MSA to the GPS oscillator.
                    I then read Scotty's post on this thread re using frequencies other than 64 MHz for the MO. So, I pulled the 64 MHz oscillator out of my MO and substituted a 32 MHz oscillator I had on hand and adjusted the configuration. All worked fine. I have only done a quick check but the only change I can see so far is the DDS's can only be used up to 16 MHz, as expected - not a problem.
                    So my aim is to design an MO phased locked to my GPS oscillator. All my test gear will then be locked to the one source. It will be about a month before I can start on this.
                    My only concern at this stage is the possible effects of phase noise from the phase locked MO. Any comments anyone?

                    Ron, VK7ZRO.
                  • Sam
                    Your scheme is certainly workable. Scotty mentioned that the on-board DDS multiplier s phase noise seems to be dwarfed by that of the PLO s. It certainly
                    Message 9 of 17 , Aug 12, 2010
                      Your scheme is certainly workable. Scotty mentioned that the on-board DDS multiplier's phase noise seems to be dwarfed by that of the PLO's. It certainly should be possible to build a phase locked oscillator that is as least as good as the one on the DDS.

                      The extreme frequency accuracy from using GPS may have some use if you are using an external output of one of the DDSs as a signal generator. I'm not sure that it actually improves the performance of the SA or VNA beyond what you would get with an ovenized oscillator. But if you already have the GPS device, it makes sense to use it.

                      Sam W.


                      --- In spectrumanalyzer@yahoogroups.com, "Ron" <ronbrown1@...> wrote:
                      >
                      >
                      > MO stability is a subject that I am quite interested in.
                      > My MSA is to the final firing up stage. All coming together nicely.
                      > Working on the RBW filters at present then I'll come back to the MO.
                      > My aim is to lock the MO to my GPS disciplined oscillator. Stability will then be a non issue.
                      > A couple of years ago I built a GPS disciplined oscillator based on the design by James Miller, G3RUH. Google will find it for you. I used a 13 MHz OCXO. Works brilliantly. It outputs a 1 MHz reference signal. I then built a DDS oscillator and frequency counter. Google "S53MV DDS" and you will find them. Brilliant devices. I then phased locked the frequency counter to the GPS disciplined oscillator. The VCXO I used in the counter can be found as eBay item 160437166617. Plenty more available.
                      > These are a very nice TC-VCXO and worth considering for a 10 MHz oscillator. If I was building the GPS oscillator again I would try using this device instead of the 13 MHz OCXO.
                      > But I had trouble finding a suitable VCXO to phase lock the DDS oscillator. I eventually found eBay item 350271667341, a 32 MHz Murata VCXO. I am yet to incorporate this into the DDS oscillator because at this stage I started working on the MSA. I then realised that this Murata VCXO might be suitable for phase locking the MSA to the GPS oscillator.
                      > I then read Scotty's post on this thread re using frequencies other than 64 MHz for the MO. So, I pulled the 64 MHz oscillator out of my MO and substituted a 32 MHz oscillator I had on hand and adjusted the configuration. All worked fine. I have only done a quick check but the only change I can see so far is the DDS's can only be used up to 16 MHz, as expected - not a problem.
                      > So my aim is to design an MO phased locked to my GPS oscillator. All my test gear will then be locked to the one source. It will be about a month before I can start on this.
                      > My only concern at this stage is the possible effects of phase noise from the phase locked MO. Any comments anyone?
                      >
                      > Ron, VK7ZRO.
                      >
                    • william sprowls
                      Hi All,  Sam took the words out of my mouth, but since I wrote this, I ll post it anyway: Hi All,  The subject of phase noise is starting to get popular, so
                      Message 10 of 17 , Aug 12, 2010
                        Hi All,
                         Sam took the words out of my mouth, but since I wrote this, I'll post it anyway:
                        Hi All,
                         The subject of phase noise is starting to get popular, so let me say a couple of things.
                         The original goal of the MSA was to build a Spectrum Analyzer on a modest budget. The primary function of any SA is to measure RF power in a limited bandwidth (Resolution). Phase noise, even lousy phase noise, has little affect on this purpose. Also, the effect of phase noise in the VNA is minor. Therefore, I will leave VNA discussion out of this.
                         Of some interest is the function of an SA to measure and analyze the phase noise of a signal. In its present form, the MSA will do that, but with extremely limited capability. In any SA, the quality of a phase noise measurement is limited by the phase noise of the measurement system.
                          The phase noise limitations in the MSA are PLO 1 and PLO 2, PLO 1 being the main contributor. The phase noise limitations of a PLO are the combined phase noise contributions of the following:
                        PLL chip (LMX2326 or ADF4112)
                        PLL loop filter
                        VCO
                        Reference oscillator (Master Oscillator and DDS combo)
                         Of course, a "perfect" MO would not contribute to MSA phase noise. Actually, the MO phase noise contribution is dominant only at very low offset frequencies from the carrier, less than 100 Hz. Above that, the other three contributors are dominant.
                         To make a long story short, a super-duper MO is an overkill for the MSA. The three other contributors are the main factors.
                         The only way to make the MSA a low phase noise system is to replace the VCO's with ultra, low noise VCO's (YIG's) and design a PLL system around them. This can not be done on a "modest" budget, unless you have a few junk box YIG Oscillators.
                        Scotty

                        ---
                        On Thu, 8/12/10, Sam <swetterlin@...> wrote:

                        From: Sam <swetterlin@...>
                        Subject: [spectrumanalyzer] Re: MO stability
                        To: spectrumanalyzer@yahoogroups.com
                        Date: Thursday, August 12, 2010, 9:21 AM

                         

                        Your scheme is certainly workable. Scotty mentioned that the on-board DDS multiplier's phase noise seems to be dwarfed by that of the PLO's. It certainly should be possible to build a phase locked oscillator that is as least as good as the one on the DDS.

                        The extreme frequency accuracy from using GPS may have some use if you are using an external output of one of the DDSs as a signal generator. I'm not sure that it actually improves the performance of the SA or VNA beyond what you would get with an ovenized oscillator. But if you already have the GPS device, it makes sense to use it.

                        Sam W.

                        --- In spectrumanalyzer@yahoogroups.com, "Ron" <ronbrown1@...> wrote:
                        >
                        >
                        > MO stability is a subject that I am quite interested in.
                        > My MSA is to the final firing up stage. All coming together nicely.
                        > Working on the RBW filters at present then I'll come back to the MO.
                        > My aim is to lock the MO to my GPS disciplined oscillator. Stability will then be a non issue.
                        > A couple of years ago I built a GPS disciplined oscillator based on the design by James Miller, G3RUH. Google will find it for you. I used a 13 MHz OCXO. Works brilliantly. It outputs a 1 MHz reference signal. I then built a DDS oscillator and frequency counter. Google "S53MV DDS" and you will find them. Brilliant devices. I then phased locked the frequency counter to the GPS disciplined oscillator. The VCXO I used in the counter can be found as eBay item 160437166617. Plenty more available.
                        > These are a very nice TC-VCXO and worth considering for a 10 MHz oscillator. If I was building the GPS oscillator again I would try using this device instead of the 13 MHz OCXO.
                        > But I had trouble finding a suitable VCXO to phase lock the DDS oscillator. I eventually found eBay item 350271667341, a 32 MHz Murata VCXO. I am yet to incorporate this into the DDS oscillator because at this stage I started working on the MSA. I then realised that this Murata VCXO might be suitable for phase locking the MSA to the GPS oscillator.
                        > I then read Scotty's post on this thread re using frequencies other than 64 MHz for the MO. So, I pulled the 64 MHz oscillator out of my MO and substituted a 32 MHz oscillator I had on hand and adjusted the configuration. All worked fine. I have only done a quick check but the only change I can see so far is the DDS's can only be used up to 16 MHz, as expected - not a problem.
                        > So my aim is to design an MO phased locked to my GPS oscillator. All my test gear will then be locked to the one source. It will be about a month before I can start on this.
                        > My only concern at this stage is the possible effects of phase noise from the phase locked MO. Any comments anyone?
                        >
                        > Ron, VK7ZRO.
                        >


                      • Ken Holt
                        Scotty-Before I proceed to install fences, I would appreciate your advice on PLO output power levels required. The block diagram of the MSA with TG and VNA
                        Message 11 of 17 , Aug 15, 2010

                          Scotty-Before I proceed to install fences, I would appreciate your advice on PLO output power levels required. The block diagram of the MSA with TG and VNA indicates that each PLO has two outputs at +10 dBm. I have that on PLO2 but each output on PLO1 and PLO3 is approximately 5.5 dBm. That agrees with the typical values Mini Circuits gives for the ROS2150VW and ERA33SM. I have seen some message traffic on low PLO output in the past and I remember you suggesting that the U5 78L05 regualtor could be replaced with a 78L06 (6.2 volts) regulator to gain a couple of db. However, that still leaves a shortfall of 2.5 to 3 dBm (in my case). I have two questions.

                           

                          1) What is an acceptable output level for PLO1 and PLO3, based on your practical experience? My guess is that +5.5 dBm is acceptable for PLO3 (with some loss in TG output) but will result in a dB per dB loss in MSA dynamic range if PLO1 is less than +10 dBm. I just don't have a feel for how much loss is tolerable in the home lab situation.

                           

                          2) If +10dBm is the desired level, I am considering replacing the -14 dB three-way splitter (R8, R10, R11, R24 and R25) with a -9.5 dB three-way splitter that consists of four 25 Ohm (24.9 @ 1%) resistors connected in a star (three prong pitchfork) configuration. I would change R7 to 56 ohms to make the synthesizer Fin input approximate 50 ohms. I would have to stand some resistors on end but it seems doable and would yield +10 dBm at the PLO outputs. Your thoughts on this approach?

                           

                          Thanks in advance for your advice.

                           

                          Ken Holt

                        • Sam
                          That s a good question for Scotty, but as long as I am online I will thrown in my two-cents worth. The 6 V regulator is definitely a good idea, and I think it
                          Message 12 of 17 , Aug 15, 2010
                            That's a good question for Scotty, but as long as I am online I will thrown in my two-cents worth. The 6 V regulator is definitely a good idea, and I think it will provide all the power you need.

                            The splitter/attenuator to which you refer is important in creating isolation between the outputs (so incoming signals at one output, resulting from leakage through a mixer, don't contaminate the other output). Some of the problematic leakage occurs at harmonics of the PLO frequencies, so it is extremely high frequency stuff. Reducing the attenuation, or sticking resistors in the air, sounds like a bad idea to me. If you go that route, maybe you can do it with 0603 resistors.

                            Sam W.

                            --- In spectrumanalyzer@yahoogroups.com, Ken Holt <kenholt2@...> wrote:
                            >
                            > Scotty-Before I proceed to install fences, I would appreciate your advice on PLO
                            > output power levels required. The block diagram of the MSA with TG and VNA
                            > indicates that each PLO has two outputs at +10 dBm. I have that on PLO2 but each
                            > output on PLO1 and PLO3 is approximately 5.5 dBm. That agrees with the typical
                            > values Mini Circuits gives for the ROS2150VW and ERA33SM. I have seen some
                            > message traffic on low PLO output in the past and I remember you suggesting that
                            > the U5 78L05 regualtor could be replaced with a 78L06 (6.2 volts) regulator to
                            > gain a couple of db. However, that still leaves a shortfall of 2.5 to 3 dBm (in
                            > my case). I have two questions.
                            >  
                            > 1) What is an acceptable output level for PLO1 and PLO3, based on your practical
                            > experience? My guess is that +5.5 dBm is acceptable for PLO3 (with some loss in
                            > TG output) but will result in a dB per dB loss in MSA dynamic range if PLO1 is
                            > less than +10 dBm. I just don't have a feel for how much loss is tolerable in
                            > the home lab situation.
                            >  
                            > 2) If +10dBm is the desired level, I am considering replacing the -14 dB
                            > three-way splitter (R8, R10, R11, R24 and R25) with a -9.5 dB three-way splitter
                            > that consists of four 25 Ohm (24.9 @ 1%) resistors connected in a star (three
                            > prong pitchfork) configuration. I would change R7 to 56 ohms to make the
                            > synthesizer Fin input approximate 50 ohms. I would have to stand some resistors
                            > on end but it seems doable and would yield +10 dBm at the PLO outputs. Your
                            > thoughts on this approach?
                            >  
                            > Thanks in advance for your advice.
                            >  
                            > Ken Holt
                            >
                          • william sprowls
                            Hi Ken, The minimum power for the L port of any of the mixers is +4 dBm. This would mean that +7 dBm would be the minimum output from the SLIM-PLO. You can
                            Message 13 of 17 , Aug 15, 2010
                              Hi Ken,
                              The minimum power for the L port of any of the mixers is +4 dBm. This would mean that +7 dBm would be the minimum output from the SLIM-PLO. You can decrease the internal attenuator values or change the power dividers as you suggest. However, this will decrease the isolation from module to module. In the SA mode, this is not a concern. In TG or VNA mode, the crosstalk will increase.
                              I would suggest completing your build and initial set-ups and calibrations. Play with your MSA a little to determine if these low outputs are detrimental. If performance suffers, I would suggest the 6.2 v regulators.
                              Scotty

                              --- On Sun, 8/15/10, Ken Holt <kenholt2@...> wrote:

                              From: Ken Holt <kenholt2@...>
                              Subject: [spectrumanalyzer] PLO Output Levels
                              To: spectrumanalyzer@yahoogroups.com
                              Date: Sunday, August 15, 2010, 5:36 PM

                               

                              Scotty-Before I proceed to install fences, I would appreciate your advice on PLO output power levels required. The block diagram of the MSA with TG and VNA indicates that each PLO has two outputs at +10 dBm. I have that on PLO2 but each output on PLO1 and PLO3 is approximately 5.5 dBm. That agrees with the typical values Mini Circuits gives for the ROS2150VW and ERA33SM. I have seen some message traffic on low PLO output in the past and I remember you suggesting that the U5 78L05 regualtor could be replaced with a 78L06 (6.2 volts) regulator to gain a couple of db. However, that still leaves a shortfall of 2.5 to 3 dBm (in my case). I have two questions.

                               

                              1) What is an acceptable output level for PLO1 and PLO3, based on your practical experience? My guess is that +5.5 dBm is acceptable for PLO3 (with some loss in TG output) but will result in a dB per dB loss in MSA dynamic range if PLO1 is less than +10 dBm. I just don't have a feel for how much loss is tolerable in the home lab situation.

                               

                              2) If +10dBm is the desired level, I am considering replacing the -14 dB three-way splitter (R8, R10, R11, R24 and R25) with a -9.5 dB three-way splitter that consists of four 25 Ohm (24.9 @ 1%) resistors connected in a star (three prong pitchfork) configuration. I would change R7 to 56 ohms to make the synthesizer Fin input approximate 50 ohms. I would have to stand some resistors on end but it seems doable and would yield +10 dBm at the PLO outputs. Your thoughts on this approach?

                               

                              Thanks in advance for your advice.

                               

                              Ken Holt


                            • jghbeta
                              For PLO1 and 3, the ROS2150VW nominal output level is specified as 4dBm by MiniCircuits. Then it is followed by a -14dBm splitter, a +18.7 dBm ERA-33S
                              Message 14 of 17 , Aug 16, 2010
                                For PLO1 and 3, the ROS2150VW nominal output level is specified as 4dBm by MiniCircuits. Then it is followed by a -14dBm splitter, a +18.7 dBm ERA-33S amplifier and a -2.5 dBm attenuator. That is a net gain of 6.2 dBm which is the output I am getting. How do we get to 10 dBm? Should we substitute the ROS2150 by a higher output unit?

                                Jim W1JGH

                                --- In spectrumanalyzer@yahoogroups.com, "Sam" <swetterlin@...> wrote:
                                >
                                > That's a good question for Scotty, but as long as I am online I will thrown in my two-cents worth. The 6 V regulator is definitely a good idea, and I think it will provide all the power you need.
                                >
                                > The splitter/attenuator to which you refer is important in creating isolation between the outputs (so incoming signals at one output, resulting from leakage through a mixer, don't contaminate the other output). Some of the problematic leakage occurs at harmonics of the PLO frequencies, so it is extremely high frequency stuff. Reducing the attenuation, or sticking resistors in the air, sounds like a bad idea to me. If you go that route, maybe you can do it with 0603 resistors.
                                >
                                > Sam W.
                                >
                                > --- In spectrumanalyzer@yahoogroups.com, Ken Holt <kenholt2@> wrote:
                                > >
                                > > Scotty-Before I proceed to install fences, I would appreciate your advice on PLO
                                > > output power levels required. The block diagram of the MSA with TG and VNA
                                > > indicates that each PLO has two outputs at +10 dBm. I have that on PLO2 but each
                                > > output on PLO1 and PLO3 is approximately 5.5 dBm. That agrees with the typical
                                > > values Mini Circuits gives for the ROS2150VW and ERA33SM. I have seen some
                                > > message traffic on low PLO output in the past and I remember you suggesting that
                                > > the U5 78L05 regualtor could be replaced with a 78L06 (6.2 volts) regulator to
                                > > gain a couple of db. However, that still leaves a shortfall of 2.5 to 3 dBm (in
                                > > my case). I have two questions.
                                > >  
                                > > 1) What is an acceptable output level for PLO1 and PLO3, based on your practical
                                > > experience? My guess is that +5.5 dBm is acceptable for PLO3 (with some loss in
                                > > TG output) but will result in a dB per dB loss in MSA dynamic range if PLO1 is
                                > > less than +10 dBm. I just don't have a feel for how much loss is tolerable in
                                > > the home lab situation.
                                > >  
                                > > 2) If +10dBm is the desired level, I am considering replacing the -14 dB
                                > > three-way splitter (R8, R10, R11, R24 and R25) with a -9.5 dB three-way splitter
                                > > that consists of four 25 Ohm (24.9 @ 1%) resistors connected in a star (three
                                > > prong pitchfork) configuration. I would change R7 to 56 ohms to make the
                                > > synthesizer Fin input approximate 50 ohms. I would have to stand some resistors
                                > > on end but it seems doable and would yield +10 dBm at the PLO outputs. Your
                                > > thoughts on this approach?
                                > >  
                                > > Thanks in advance for your advice.
                                > >  
                                > > Ken Holt
                                > >
                                >
                              • william sprowls
                                Hi Jim and All, Here are the numbers that I have for PLO1 and PLO2 for the current design: Minicircuits ROS-2150VW = +5 dBm guaranteed minimum from 1000 to
                                Message 15 of 17 , Aug 16, 2010
                                  Hi Jim and All,
                                  Here are the numbers that I have for PLO1 and PLO2 for the current design:
                                  Minicircuits ROS-2150VW = +5 dBm guaranteed minimum from 1000 to 2000 MHz.
                                  3 way power divider = -13.3 dB attenuation
                                  ERA-33 gain = 19.5 dB minimum at 1 GHZ, 18 dB at 2 GHz
                                  PLO1 and PLO3 output pads = 2.7 dB attenuation
                                  Internal pads in Mixers = 2.5 dB attenuation.
                                  + 5 dBm - 13.3 dB + 19 dB - 2.7 dB - 2.5dB = +5.5 dBm nominal power to the mixer port (+4.5 dBm worse case).

                                   Originally, the Minicircuits ROS-2150VW was rated at +10volts for Vcc with at output of +10 dBm. When I got my 2, they had changed the spec to +5v with an output of +8 dBm. Mine measured an output of +8 dBm at 1000 MHz to +7 dBm at 2000 MHz. They also spec'ed the ERA-33 at 20 dB gain (which I duplicated). I can't control Minicircuits changing their specs, but the present parts and configuration should still give good results in the MSA.
                                  I have an idea that the Minicircuits ROS-2150VW could be operated at +10volts, but I have not gambled with the $30 part. + 6.2  volts would be no problem, however.

                                  At one time, the 3 way power divider was designed for 9.5 dB loss. This probably accounts for my loss of memory in thinking the output should be much higher.
                                  Scotty

                                  --- On Mon, 8/16/10, jghbeta <jghalpha@...> wrote:

                                  From: jghbeta <jghalpha@...>
                                  Subject: [spectrumanalyzer] Re: PLO Output Levels
                                  To: spectrumanalyzer@yahoogroups.com
                                  Date: Monday, August 16, 2010, 10:44 AM

                                   

                                  For PLO1 and 3, the ROS2150VW nominal output level is specified as 4dBm by MiniCircuits. Then it is followed by a -14dBm splitter, a +18.7 dBm ERA-33S amplifier and a -2.5 dBm attenuator. That is a net gain of 6.2 dBm which is the output I am getting. How do we get to 10 dBm? Should we substitute the ROS2150 by a higher output unit?

                                  Jim W1JGH

                                  --- In spectrumanalyzer@yahoogroups.com, "Sam" <swetterlin@...> wrote:
                                  >
                                  > That's a good question for Scotty, but as long as I am online I will thrown in my two-cents worth. The 6 V regulator is definitely a good idea, and I think it will provide all the power you need.
                                  >
                                  > The splitter/attenuator to which you refer is important in creating isolation between the outputs (so incoming signals at one output, resulting from leakage through a mixer, don't contaminate the other output). Some of the problematic leakage occurs at harmonics of the PLO frequencies, so it is extremely high frequency stuff. Reducing the attenuation, or sticking resistors in the air, sounds like a bad idea to me. If you go that route, maybe you can do it with 0603 resistors.
                                  >
                                  > Sam W.
                                  >
                                  > --- In spectrumanalyzer@yahoogroups.com, Ken Holt <kenholt2@> wrote:
                                  > >
                                  > > Scotty-Before I proceed to install fences, I would appreciate your advice on PLO
                                  > > output power levels required. The block diagram of the MSA with TG and VNA
                                  > > indicates that each PLO has two outputs at +10 dBm. I have that on PLO2 but each
                                  > > output on PLO1 and PLO3 is approximately 5.5 dBm. That agrees with the typical
                                  > > values Mini Circuits gives for the ROS2150VW and ERA33SM. I have seen some
                                  > > message traffic on low PLO output in the past and I remember you suggesting that
                                  > > the U5 78L05 regualtor could be replaced with a 78L06 (6.2 volts) regulator to
                                  > > gain a couple of db. However, that still leaves a shortfall of 2.5 to 3 dBm (in
                                  > > my case). I have two questions.
                                  > >
                                  > > 1) What is an acceptable output level for PLO1 and PLO3, based on your practical
                                  > > experience? My guess is that +5.5 dBm is acceptable for PLO3 (with some loss in
                                  > > TG output) but will result in a dB per dB loss in MSA dynamic range if PLO1 is
                                  > > less than +10 dBm. I just don't have a feel for how much loss is tolerable in
                                  > > the home lab situation.
                                  > >
                                  > > 2) If +10dBm is the desired level, I am considering replacing the -14 dB
                                  > > three-way splitter (R8, R10, R11, R24 and R25) with a -9.5 dB three-way splitter
                                  > > that consists of four 25 Ohm (24.9 @ 1%) resistors connected in a star (three
                                  > > prong pitchfork) configuration. I would change R7 to 56 ohms to make the
                                  > > synthesizer Fin input approximate 50 ohms. I would have to stand some resistors
                                  > > on end but it seems doable and would yield +10 dBm at the PLO outputs. Your
                                  > > thoughts on this approach?
                                  > >
                                  > > Thanks in advance for your advice.
                                  > >
                                  > > Ken Holt
                                  > >
                                  >


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