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Re: Anyone built the Ensemble RXTX for 40-30- & 20 meters ?

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  • pauldebono@rocketmail.com
    John, 0.5 watts is just about the 4 volts I am getting !! It will be interesting to remove C27, the 330pf connected to the switching FET, Q10, and see what
    Message 1 of 98 , Jan 1, 2013
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      John,

      0.5 watts is just about the 4 volts I am getting !!

      It will be interesting to remove C27, the 330pf connected to the switching FET, Q10, and see what happens.

      Have you ever came across of a T37-6 or some other core, with a different permeability , characteristics or even tolerance , from those specified ??

      I have checked the capacitors values, out of circuit. But suspicious capacitors tend to behave differently in-circuit, with power on !

      Since you mentioned Q6, here are the measurements I got on the secondary of T3 !

      On R47: 40M 120mV 30M 160mV 20M 100mV
      On R46 142mV 115mV 100mV (WORTH NOTHING !)

      As for an outboard LPF, I have plenty, some factory wound, from a partial kit, and other home brewed. That's interesting !

      Paul
      9H1FQ

      --- In softrock40@yahoogroups.com, John Greusel <greusel@...> wrote:
      >
      > Paul,
      > I do have that exact unit (40,30,20) and I can output roughly 1 watt at 20 meters. Warren would probably say he can bump that up or down .5 watts with the simple change of a mosfet.
      > There has been considerable discussion about this topic over several years and if you do a search within this group you'll find references to it but so far it's been inconclusive at best. It might be interesting to jumper the LPF on the board and breadboard a few different filters on a proto board and see what you get. If you discover the source of this lament (you're not the first) we'll award you the "Hats Off" award for good detective work. Warren probably has a 40,30,20 too (since he has one of everything :-))  and can quote you chapter and verse the power output potential employing different configurations of the PA. You could be right and I only have 1 watt because I have a "robust" Q6. I just don't understand how the filter could be wrong unless there is some inefficiency (or as you say interaction with other elements of the circuit) that has been overlooked.
      >  
      > John
      > KC9OJV
      >
      >
      >
      > ________________________________
      > From: "pauldebono@..." <pawlud@...>
      > To: softrock40@yahoogroups.com
      > Sent: Tuesday, January 1, 2013 12:57 PM
      > Subject: [softrock40] Re: Anyone built the Ensemble RXTX for 40-30- & 20 meters ?
      >
      >
      >  
      > John,
      >
      > I must stress, that I need feedback from a particular version, the Ensemble RXTX 40-30-20 meters. Other versions have different values for the low pass filter !.
      >
      > I measured all the driver/pa voltages, with an RF probe. Even the simplest home made diode probe, should not behave significantly different between 40 and 20 meters. I also, reduced the tone input level, to a safe level, able to check the said stages, safely, with a frequency counter, to avoid overloading and any harmonic measurements etc. All components as per builders notes, and in their proper places !
      >
      > I got this result:
      >
      > At base of Q6 (DRIVER) 40M 85mV 30M 92mV 20M 73mV
      >
      > Other measurements made on the secondary of T3, may be irrelevant
      >
      > At secondary T4 (PA OUTPUT XFORMER) 40m 8.5v 30m 7.6v 20m 10.7v
      >
      > On 40m & 30m, full power appears at the antenna output
      >
      > On 20m, Junction of L2 and C25 (470pf) is only 4 volts !
      >
      > Reduced turns on L2 from 16 to 12, and the voltage came up to 10.7 volts, and still indicating a frequency of 14Mhz !
      >
      > Before modifying L3 as well, I want to make sure that I am on the right track.
      > That is why I am asking for feedback from constructors of this particular version. Maybe no one noticed these facts,or the problem could be caused by another part of the circuit, which is indirectly affecting the bandwidth of the LPF !
      >
      > Paul
      >
      > --- In softrock40@yahoogroups.com, John Greusel <greusel@> wrote:
      > >
      > >
      > >
      > >  Paul,
      > >
      > > I have built it and use it daily.
      > > I had a 20 meter ssb QSO with someone in PA Sunday and a couple 20 meter PSK31 contacts last night.
      > > I get less output on 20 than 40 and I get more output from a 30,20,17 SR63ng (essentially the same) as a 6.3)
      > >  than my 40,30,20 Softrock RXTX. 
      > > Warren did a lot of research recently and determined that output is very closely tied to the PA bias circuit- Q6 I think.
      > > All that being said there's nothing remarkable about that filter- you can check it yourself with an online calculator.
      > > I would check the actual inductance if you have a means of measuring it.
      > > Something isn't right- you're essentially experiencing a giant insertion loss.
      > >
      > > John
      > > KC9OJV
      > >
      > >
      > >
      > > ________________________________
      > > From: "pauldebono@" <pawlud@>
      > > To: softrock40@yahoogroups.com
      > > Sent: Tuesday, January 1, 2013 10:34 AM
      > > Subject: [softrock40] Re: Anyone built the Ensemble RXTX for 40-30- & 20 meters ?
      > >
      > >
      > >  
      > > John,
      > >
      > > I have checked it a hundred times.
      > > All components on the PA stage are as per builders note, all in their correct places and proper values.
      > >
      > > There is full one watt at T4 secondary on 14Mhz, but goes down to 4 volts at C25 with 16 turns on T37-6 yellow core. Reducing to 12 turns, yealds full one watt on 14 Mhz. But on C26, still 4 volts.
      > > I have checked the frequency, by reducing the input level and using a frequency counter !
      > > Before shortening from 16 to 12 turns on L3, I want to hear from others who have actually built this particular 40-30-20 m version, not just any other version !
      > >
      > > Paul
      > >
      > > --- In softrock40@yahoogroups.com, John Greusel <greusel@> wrote:
      > > >
      > > > Might be worth a check to see if you've got C25 in the position of C24 or C26. That would be about the right shift in C value to skew the whole thing. This 5 element filter has been used hundreds (or thousands) of time successfully with this design.
      > > >
      > > > John
      > > > KC9OJV
      > > >  
      > > >
      > > >
      > > >
      > > > ________________________________
      > > > From: Alan <alan4alan@>
      > > > To: softrock40@yahoogroups.com
      > > > Sent: Tuesday, January 1, 2013 8:37 AM
      > > > Subject: Re: [softrock40] Anyone built the Ensemble RXTX for 40-30- & 20 meters ?
      > > >
      > > >
      > > >  
      > > >
      > > > ----- Original Message -----
      > > > Subject: [softrock40] Anyone built the Ensemble RXTX for 40-30- & 20 meters ?
      > > >
      > > > >I am getting low PA output on 20 meters
      > > > > Reduced L2 to 12 turns and the output at L2 increased to 10volts at 14 Mhz.
      > > > >
      > > > > Would like to hear from builders of this version to verify if the LPF coils should be 16 turns on T37-6 yellow core, as per
      > > > > builders notes !!
      > > > >
      > > >
      > > > Paul,
      > > >
      > > > I've not built one but the values quoted seem correct.
      > > > And I do not think it is a known problem.
      > > > It is possible you have a rogue core or capacitor.
      > > > What is the voltage at the input of the LPF?
      > > >
      > > > 73 Alan G4ZFQ
      > > >
      > >
      >
    • R. R. (Robby) Robson
      Gentlemen: Please review the projects on the new WB5RVZ website. I have added a Revisions/Errata tab to the menu on each project. Not much populated there,
      Message 98 of 98 , Jan 7, 2013
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        Gentlemen:

        Please review the projects on the new WB5RVZ website.
        I have added a "Revisions/Errata" tab to the menu on each project.  Not much populated there, but the RXTX info that was raised in this thread has been posted.

        Check it out.

        On Sun, Jan 6, 2013 at 9:43 AM, richard.lawn@... <rjlawn@...> wrote:
         

        I couldn't agree more about the need to make a clear errata page obvious and available on the website with dates. Tnx for making this suggestion.
        Rick
        W2JAZ



        --- In softrock40@yahoogroups.com, "hladikz" wrote:
        >
        > Hi Oms,
        >
        > I just ended RXTXE building and found those build changes for 40/30/20 version.
        >
        > I think that it will be very nice if you will add errata/changes subpage to your new documentation web. Date of changes will be also very usable. At this time if I am coreect there are two changes:
        >
        > 1. Crossing of ant TR leads
        > 2. changes of values for 40/30/20 LPF C's and L's (please add also previous number of winds for L, to allow avoid recounting of winds)
        >
        > Yet something missing?
        >
        > I also think that way of band variant selection is not very clear. Especially for beginners it is not simple to recognize that you must go to band subpage. It will be more friendly if there will be possibility to change bands variant on each page.
        >
        > On other way I think that Softrock DOC at all is excelent and very easy to understand.
        >
        > 73 Zdenek OK7DR
        >
        >
        >
        > --- In softrock40@yahoogroups.com, "R. R. (Robby) Robson" wrote:
        > >
        > > I have made the changes to the documentation. See
        > > http://wb5rvz.org/ensemble_rxtx/05_rf (be sure to select the 40/30/20m band
        > > option).
        > >
        > > On Thu, Jan 3, 2013 at 10:33 AM, pauldebono@
        > > wrote:
        > >
        > > > **
        > > >
        > > >
        > > > Tony,
        > > >
        > > > Thanks very much.
        > > >
        > > > I was the the one who raised the issue.
        > > > I had already started reducing the turns and was going to make the
        > > > capacitors variable to determine the optimum values.
        > > >
        > > > 73's
        > > >
        > > > Paul
        > > > 9H1FQ
        > > >
        > > >
        > > > --- In softrock40@yahoogroups.com, "Parks, Tony" wrote:
        > > > >
        > > > > Good Morning All,
        > > > >
        > > > > Sure looks like it would be appropriate to make the 40m/30m/20m LP filter
        > > > > component changes starting right away.
        > > > >
        > > > > I will get the schematic values changed today with the following changes:
        > > > >
        > > > > C24 and C26 each become 180pF
        > > > > C25 becomes 390pF
        > > > > L2 and L3 each become 0.6uH, 14 turns of #26 wire on T37-6 cores.
        > > > >
        > > > > A continue to appreciate the thoughtful input from the group and hope the
        > > > > kits are still providing a positive entry level SDR experience for many.
        > > > >
        > > > > Thanks and 73,
        > > > > Tony KB9YIG
        > > > >
        > > > > On Thu, Jan 3, 2013 at 8:15 AM, John Greusel wrote:
        > > > >
        > > > > > **
        > > >
        > > > > >
        > > > > >
        > > > > > My vote is that Tony's suggested change and Warren's empirical results
        > > > > > point strongly to this modest change as a good thing.
        > > > > > The prior variance in output for different builders makes me think it's
        > > > > > related to the bias differences (via Q6) that Warren uncovered
        > > > recently. In
        > > > > > other words, those of us that are experiencing near 1 watt output are
        > > > > > actually having much higher output with attenuation.
        > > > > >
        > > > > > John
        > > > > > KC9OJV
        > > > > >
        > > > > >
        > > > > > ------------------------------
        > > > > > *From:* warrenallgyer
        > > > > > *To:* softrock40@yahoogroups.com
        > > > > > *Sent:* Thursday, January 3, 2013 5:31 AM
        > > > > >
        > > > > > *Subject:* [softrock40] Re: Anyone built the Ensemble RXTX for 40-30- &
        > > >
        > > > > > 20 meters ?
        > > > > >
        > > > > >
        > > > > > I have bread-boarded and tested Tony's suggested filter with caps of
        > > > > > 180,390,180 pF and T37 toroids with 14 turns, again terminated in 47
        > > > ohms
        > > > > > and fed directly by the output of an MFJ antenna analyzer.
        > > > > >
        > > > > > 7 MHz: Reference at 0 dB
        > > > > > 10 MHz: -0.1 dB
        > > > > > 14.2 MHz: -.7 dB
        > > > > > 16.3 MHz: -3.0 dB
        > > > > > 20 MHz: -12.3 dB
        > > > > > 21 MHz: -15.2 dB
        > > > > >
        > > > > > Warren Allgyer - W8TOD
        > > > > >
        > > > > > --- In softrock40@yahoogroups.com, "warrenallgyer" wrote:
        > > > > > >
        > > > > > > I just calculated different results with the external filter. The
        > > > > > > results reported previously were a comparison of simultaneous
        > > > readings
        > > > > > > on the input and the terminated output of the filter.
        > > > > > > The new readings are looking at the terminated output only and using
        > > > the
        > > > > > > value at 7MHz as the reference. Doing it this way I get
        > > > > > > 7 MHz: 0 dB10 MHz: -0.1 dB13.5 MHz: -3.3 dB14.0 MHz: -4.8 dB14.2 MHz:
        > > > > > > -5.4 dB 14.5 MHz: -6.6 dB
        > > > > > > The output of the analyzer, when terminated and measured separately
        > > > > > > across the range 7 - 14.5 MHz is flat within 0.2 dB.
        > > > > > > The discrepancy between the early results with simultaneous input and
        > > > > > > output measurements is the input impedance of the filter changes as
        > > > the
        > > > > > > filter begins to engage and that causes the voltage to rise. These
        > > > > > > latter results are more appropriate and still show a significant
        > > > problem
        > > > > > > with the specified turns counts and cap values
        > > > > > > I will build Tony's suggested filter and model it the same way.
        > > > > > >
        > > > > > >
        > > > > > > Warren Allgyer - W8TOD
        > > > > > >
        > > > > > > --- In softrock40@yahoogroups.com, "Parks, Tony" wrote:
        > > > > > > >
        > > > > > > > 16 turns on a T37-6 core is supposed to result in an 0.8uH inductor
        > > > > > > > according to the calculator on Diz's website.
        > > > > > > http://toroids.info/T37-6.php
        > > > > > > >
        > > > > > > > Checking the 40m/30m/20m LP filter design with AADE Filter Design
        > > > v4.5
        > > > > > > I
        > > > > > > > see about 1dB of additional attenuation at 14.3 MHz compared to
        > > > lower
        > > > > > > > frequencies.
        > > > > > > >
        > > > > > > > My recent experience with a freshly built 40m/30m/20m RXTX board
        > > > was
        > > > > > > the
        > > > > > > > 20m output was down about 1.5 dB.
        > > > > > > >
        > > > > > > > The capacitors supplied in the RXTX kit are 5%. Increasing
        > > > capacitor
        > > > > > > and
        > > > > > > > inductor values by 5% results in 2.5 dB 20m attenuation. Increasing
        > > > > > > > capacitor values by 5% and inductor values by 10% results in about
        > > > > > > 3.2 dB
        > > > > > > > of additional attenuation.
        > > > > > > >
        > > > > > > > The design seems to be reasonable but some kit builder's experience
        > > > > > > > suggests that the filter should be changed. Changing the 220pF
        > > > > > > capacitors
        > > > > > > > to 180pF, the 470pF capacitor to 390pF and the inductors to 0.6uH,
        > > > (14
        > > > > > > > turns on a T37-6 core), results in a LP filter with about the same
        > > > Z
        > > > > > > but
        > > > > > > > the 1dB of additional attenuation is at 18 MHz.
        > > > > > > >
        > > > > > > > Thoughts?
        > > > > > > >
        > > > > > > > Tony KB9YIG
        > > > > > > >
        > > > > > > > On Thu, Jan 3, 2013 at 4:14 AM, Orin wrote:
        > > > > > > >
        > > > > > > > > **
        > > > > > > > >
        > > > > > > > >
        > > > > > > > > --- In softrock40@yahoogroups.com, "warrenallgyer" wrote:
        > > > > > > > > >
        > > > > > > > > > Further to the above post:
        > > > > > > > > >
        > > > > > > > > > I have breadboarded the 43/30/20 filter externally, feeding it
        > > > > > > from an
        > > > > > > > > MFJ
        > > > > > > > > > antenna analyzer and terminating it on the breadboard with a 47
        > > > > > > ohm
        > > > > > > > > resister. I
        > > > > > > > > > have dual scope probes on for simultaneous measurement on the
        > > > > > > input and
        > > > > > > > > output
        > > > > > > > > > of the filter.
        > > > > > > > >
        > > > > > > > > Will you antenna analyzer measure inductance @ 14MHz? If so, what
        > > > > > > does it
        > > > > > > > > measure your inductors at. My 259B will give a result +/- 10nH
        > > > or so
        > > > > > > which
        > > > > > > > > is close enough for these filters.
        > > > > > > > >
        > > > > > > > >
        > > > > > > > > >
        > > > > > > > > > The 6 dB point of my breadboard filter is 12.5 MHz. At 14.2 MHz
        > > > > > > the
        > > > > > > > > output is 13
        > > > > > > > > > dB down.
        > > > > > > > > >
        > > > > > > > > > Toroids are T37 Yellow each 16 turns. Caps are 220 pf input and
        > > > > > > output
        > > > > > > > > shunts
        > > > > > > > > > with 470 pf. in the center shunt.
        > > > > > > > >
        > > > > > > > > I put those values into Elsie (800nH for the inductors) and got
        > > > > > > -1.3dB at
        > > > > > > > > 14.2MHz assuming 50 ohms input and your 47 ohms ouput. I tried
        > > > > > > adding 10%
        > > > > > > > > to the inductors (880nH) and got -2.6dB at 14.2MHz. 16 turns on a
        > > > > > > T37-6
        > > > > > > > > should give 768nH though and Elsie give -1dB at 14MHz in that
        > > > case.
        > > > > > > > >
        > > > > > > > > Another thing to try would be 14 turns on an T37-2 if you have
        > > > any
        > > > > > > around
        > > > > > > > > (I do from unused options on my Ensemble). The -2s have been more
        > > > > > > reliable
        > > > > > > > > for me in getting the 'advertised' inductance.
        > > > > > > > >
        > > > > > > > > Anyone wondering what "Elsie" is, it's an LC filter
        > > > design/network
        > > > > > > > > analysis program. I'm using the free student/hobbyist version.
        > > > > > > Details are
        > > > > > > > > here: http://tonnesoftware.com/elsie.html . I wish I could
        > > > justify
        > > > > > > > > spending the money for the full version.
        > > > > > > > >
        > > > > > > > > Orin.
        > > > > > > > >
        > > > > > > > >
        > > > > > > > >
        > > > > > > >
        > > > > > >
        > > > > >
        > > > > >
        > > > > >
        > > > > >
        > > > > >
        > > > >
        > > >
        > > >
        > > >
        > >
        > >
        > >
        > > --
        > > Cheers,
        > > Robby
        > >
        > > Richard R. (Robby) Robson
        > > LTC USA (RET)
        > > www.wb5rvz.com
        > > www.wb5rvz.org
        > > www.rafino.org
        > >
        >




        --
        Cheers,
        Robby
         
        Richard R. (Robby) Robson
        LTC USA (RET)
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