Welcome to the Home Page of Chuck Adams, K7QO

This page updated March 26, 2015.

Material that was here previously will reappear, so be patient.



I bought a TenTec Paragon 585 transceiver at an auction for a ridiculously low price. It has low output and I am going to refurbish it.

  • TenTec Paragon 585 Alignment Manual. March 3, 2015.
  • TenTec Paragon 585 User Manual. March 3, 2015.
  • TenTec Paragon 585 User Manual with Schematics. March 12, 2015.



    The Famous K7QO Code Course

    Here is the K7QO Code Course 3.0 in ISO format. Enjoy. Feel free to use and give away. Teach a class and make me proud. As of Jan 2015, more than 16,000 copies have been given away worldwide.

  • K7QO Code Course. Back online March 6, 2015.



    TenTec Paragon 585 Restoration Project - March 2015

    Here are some photos to show the progress and steps taken to fix a TenTec Paragon 585, circa 1985. I got this from an auction for $150 US dollars. As you can see from the photos, it is in excellent shape. I am going to make it better or at least try. Not failure, but low aim is crime. Since I have very little invested in the rig, I am not willing to spend $110 an hour and the risk of shipping across the country to have it looked at. If I can't repair it, then I am not as educated as I think I am. Educated beyond my intelligence level and spent a lot of money on books. :-) I do love a challenge.

    Click on thumbnails to get a larger image.

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    Photo 1:  Front of Paragon 585 with cover removed.
    
    Photo 2:  Top View of the insides.
    
    Photo 3:  Back Left section of transceiver.
    

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    Photo 4:  81340 board.
    
    Photo 5:  Scratches on top cover.
    
    Photo 6:  500Hz 6.3MHz IF Crystal Filter
    
    Photo 7:  Restored top cover.
    

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    Photo 8:  P/S and Cover.
    
    Photo 9:  P/S side view.  Yikes.  Water soaked at one time.  Katrina?
    
    Photo 10:  Rectifier board.
    
    Photo 11:  Speaker.  Corrosion definitely due to exposure to water.
    
    Photo 12:  Crowbar circuit board.  Definitely a layer of some crud.
    
    Photo 13:  Power transformer with serious corrosion.   But, the darn things works just fine.
    
    Photo 14:  PCB cleaned with CRC Contact Cleaner from Home Depot electrical department area.
    

    Had I known the shape of the power supply, I would have never plugged the rig in and turned it on. I assumed, and incorrectly so, that because the inside of the Paragon was clean that the power supply would be in the same shape and thus I plugged it in. Even worked a couple of stations on 20m at 11W output. After listening in another receiver to make sure the signal was clean.

    I'm invoking the DFW rule. Don't Fool With it. It is working, the PLL stays locked, so damn the torpedoes and full speed ahead..... March 20, 2015. Hell of way to start Spring.



    The K7QO Crystal Test Fixture

    In 1961 I started at McMurry College working on degrees in physics and mathematics. The first day I went into the office of Dr Virgil E Bottom, chair of the department of physics, and was hired immediately as a research assistant to work on a quartz crystal research project that was funded by James Knight, HP and Collins Radio. This was due to the fact that I knew how to grind quartz crystals, having done so as a Novice to get World War II surplus FT-243 crystals moved from outside the ham bands into the novice bands. This was at the time (1957) when novices were required to be crystal controlled.

    I had to derive two sets of equations for the resonant modes quartz crystal unit for resonant frequencies. One set of two equations for the crystal itself and one set for the crystal in series with a capacitor.

    The equivalent circuit for a quartz crystal unit is:

    The R, L and C are the motional parameters for the quartz crystal unit. There are no inductor, capacitor or resistors in the quartz crystal unit (except for C_0). The piezoelectric effect and resonance makes the system act like there is. I will use the subscript m to indicate the motional parameters in the following equations.

    I set up the equation for the impedance between points A and B, crunched the numbers and then solved a quadratic equation for the two roots for resonance. I obtained two roots.

    \omega_s = \sqrt{\frac{1}{L_m C_m}}

    where

    \omega_s = 2 \pi f_s

    for the series resonant frequency and

    \omega_a = \sqrt{\frac{1}{L_m C_m}+\frac{1}{L_m C_0}}

    for the parallel resonant or anti-resonant frequency. Note that this frequency is always higher than the series resonant frequency.

    I will come back later, after a paper I submitted gets rejected or accepted, and show all the math, for the inquiring minds in the Universe. In the meantime, you can try to derive the equations yourself.

    Now. For the circuit:

    the impedance equation yields two roots

    \omega_c = \sqrt{\frac{1}{L_m C_m}+\frac{1}{L_m (C_0 + C_x)}}

    and

    \omega_a = \sqrt{\frac{1}{L_m C_m}+\frac{1}{L_m C_0}}

    The subscript c is to show that the equation is for the case with the crystal in series with a capacitor. You will also note that the parallel resonant frequency did not change and is not affected by C_x. Once again note that the series resonant frequency is lower than the parallel resonant frequency.

    It is also important to note that C_0 \mbox{ and } C_x MUST include stray capacitance in the fixture. This was not an issue in the true series resonant frequency for the first case without the series cap.

    Here is the schematic for my fixture.

    Here is a photograph of the fixture I built using the muppet board PCB technique and showing the input cable from a NorCal FCC-2 DDS RF generator and an output cable going to an HP RF voltmeter.

    The values for R3 and R4 should be around 10 ohms or slightly lower. It is not critical. If you make them too low you will require an extra sensitive RF voltmeter. With 0.5V input from the FCC-2, the output voltage at resonance is on the order of 15mV at the peak. If you make R3 and R4 larger, you will broaden the peak and increase the voltage and make it more difficult to find the resonant point within 1 Hz. BTW, you must do this with a frequency counter or DDS with 1Hz resolution to get accurate results. My Cx value was around 47pF. The fixture has an approximate input and output impedance of 50 ohms dependent upon the Rm of the crystal at resonance. Once again, not critical.

    Too large of a value for R3 and R4 will give you a value for Rm that is going to be higher than the actual value of the crystal due to the loading factor. Also, the lower R3 and R4 values will swamp additional distributed capacitance of the fixture.

    Note that I used an Augat machined socket for the crystal. I soldered the center pin to ground to reduce the distributed capacitance of the socket. I use 0.10" headers for the shorting of Cx and a Berg connector. I even cut a portion of the header off to reduce the distributed capacitance. The cap is a NPO mono at 47pF.

    It is important to use a good L/C meter and measure the capacitance across the socket and across the jumper without the cap before building the rest of the circuit. Accurately measure Cx before installing. This will determine just how well your results are going to be

    OK. How do we do the measurements and the calculations?

  • Place crystal in holder with Cx shorted.
  • Used DDS RF generator to find the series resonant frequency. Monitor output RF voltage as you sweep the crystal. Start a KHz or so lower than the marked frequency on the crystal and carefully move up til you find the peak output. You will need to practice on this. The Q is very high and the peak very sharp and you must might miss it if you start out with too high a step size in moving the frequency. At the peak you should be able to find it within a Hz. I know that I can with my setup.
  • Write down the frequency for the peak as f_s. Also note the output voltage and write it down.
  • With everything as is, remove the crystal. Replace it with a variable resistor. I use a 25 turn Cermet trim pot with 0.2" lead spacing between the two out leads and short the middle lead to one of the outter leads. Put this in place of the crystal and adjust to get the exact same output voltage. Remove and measure the resistance. This is Rm, the ESR or motional resistance of the crystal.
  • Put crystal back in socket and remove the jumper, the Berg connector in may case. Now move the DDS generator up in frequency to find the next peak. Should be about 500Hz or so. Write this frequency down as f_c.
  • Remove crystal from socket and put it into an L/C meter and measure the capacitance. This is C0. This is due to the plating on the crystal and the leads. Use the best L/C meter you can afford. I use a Chinese L/C meter model LC-100A that works for me. I find it gets better results than my AADE L/C Meter II, which is a good meter, but on some days it is off by 5 percent or more. Go figure.

    Now you are ready to do some math. You have f_s and f_c. You have C0 and Cx and you have the stray capacitance across the crystal socket and the jumper. Calculate C_t as the sum of all four cap values. Plug into the following equation.

    L_m = \frac{1}{4 \pi^2 (f_c + f_s) (f_c - f_s) C_t}

    OK, now plug and play. Note. A lot of people may have a formula that looks similar to this. If they have a term that looks like:

    2 \cdot \Delta f \cdot f

    Then they made an approximation to the difference of two large square numbers. That kills off some of the precision and accuracy in the calculation. Use my formula. Also, use some mathematical software like Mathematica, Maple, Wolfram Alpha or other software to do the calculation. You need at least 10 or more significant digits to get good results, even though the results are only good to 4 or 5 places depending upon how well you can measure capacitance.

    You get Cm from the first formula

    C_m = \frac{1}{4 \pi^2 f_s^2 L_m}

    and you get the Q from the formula

    C_m = \frac{2 \pi f_s L_m}{R_m}

    and there you have it.

    OK. I know you doubt my sanity. So, to prove to you that this stuff works. I sent off a set of crystals to the great state of Colorado months ago. Tom Thomson, W0IVJ, and Larry Benko, W0QE, measured the parameters for the crystals using their own AIM 4170 VNAs. Here are their results.

    Lab      Crystal  FSeries      FParallel      Rs       Ls(mH)       Cs(pf)        Cp(pf)     Qs   Measuring
    Tech     Number                                                                                   Instrument
    
    W0IVJ     1      3.578426      3.585154     49.822    139.418      0.0141885      3.780     65801 AIM 4170 VNA
    W0QE      1      3.578427      3.585256     49.700    142.449      0.0138866      3.638     64443 AIM 4170 VNA
    
    W0IVJ     2      4.193154      4.200966     16.943    111.185      0.0129572      3.484    180122 AIM 4170 VNA
    W0QE      2      4.193163      4.200894     17.159    115.719      0.0124495      3.376    177674 AIM 4170 VNA
    
    W0IVJ     3      4.031548      4.036547     40.962    309.640      0.0050332      2.032    211124 AIM 4170 VNA
    W0QE      3      4.031552      4.036428     40.046    340.051      0.0045830      1.895    215101 AIM 4170 VNA
    
    W0IVJ     4      4.193152      4.201202     18.176    107.122      0.0134487      3.509    165524 AIM 4170 VNA
    W0QE      4      4.193157      4.201100     18.432    112.633      0.0127907      3.376    160993 AIM 4170 VNA
    
    W0IVJ     5      4.094814      4.102963     23.238    134.404      0.0112398      2.830    147508 AIM 4170 VNA
    W0QE      5      4.094819      4.103052     23.469    134.440      0.0112368      2.794    147386 AIM 4170 VNA
    
    W0IVJ     6      3.998939      4.005005     22.484    132.716      0.0119351      3.940    153331 AIM 4170 VNA
    W0QE      6      3.998953      4.005015     22.619    136.166      0.0116326      3.837    151261 AIM 4170 VNA
    
    W0IVJ     7     11.055203     11.079818      7.407     11.640      0.0178059      4.007    109648 AIM 4170 VNA
    W0QE      7     11.055211     11.079788      7.337     11.755      0.0176319      3.965    111282 AIM 4170 VNA
    
    W0IVJ     8      4.094873      4.102956     24.034    130.270      0.0115962      2.943    144651 AIM 4170 VNA
    W0QE      8      4.094876      4.103023     24.476    134.745      0.0112110      2.818    141641 AIM 4170 VNA
    
    W0IVJ     9     13.499968     13.529170      4.063      5.074      0.0273900      6.345    100390 AIM 4170 VNA
    W0QE      9     13.499973     13.529200      4.129      5.064      0.0274465      6.339    104041 AIM 4170 VNA
    
    
    Crystal Identification Printed on Each Unit
    
    1  HC-49U  MPCO  3.579545
    2. HC-49U  HOSONIC 4.1943 B603
    3. HC-49S  4.032
    4. HC-49U  HOSONIC 4.1943 B603
    5. HC-49U  MMD A18BA1 4.096JHz 9942G
    6. HC-49U  ABRACON 4.000 AB 0443
    7. HC-49U  FOX115-20 11.0592
    8. HC-49U  MMD A18BA1 4.096MHz
    9. HC-49U  78941-1  13.500 KDS 5K
    

    This morning, March 23rd, 2015, I took the above fixture and measured crystal 1-6 and here is what I got.

    Nr    f_s       f_c        C0         Lm           Cm         Rm         Q
    1   3573435   3578898    3.65pF    144.38mH      13.70fF     47.1     68,900
    2   4193162   4193654    3.45pF    115.13mH      12.51fF     15.7    193,200
    3   4031554   4031738    1.97pF    329.34mH       4.73fF     39.7    210,100
    4   4193162   4193664    3.37pF    113.01mH      12.75fF     16.3    182,700
    5   4094821   4095266    2.75pF    132.08mH      11.44fF     22.4    151,700
    6   3998949   3999388    3.66pF    134.77mH      11.75fF     21.4    158,200
    

    As you can see, excellent agreement. Resistance values a few ohms low and I think that is due to inductance in variable resistor and I'm going to return to try another variable resistor to see the Cermet variable does indeed have distributed inductance in it. Film at 11, meaning I'll get back on it PDQ.

    March 26, 2015, 0230 UTC. OK, put the Cermet 25T variable resistor into the AADE L/C II meter and found 1.0uH. That means at 7MHz I've got 50 ohms of inductive reactance in the circuit, so my voltage out match is off due to the inductance. So, next step is to take an ordinary trim pot and make a small board with leads to fit the socket and remeasure all the R_m values. This will, in turn, change the Q values for the crystals. Stay tuned.




    My email address is the usual hiding from Internet bots.

    chuck dot adams dot k7qo at gmail dot com

    100 Books to Read Before You Die

    Having just watched 'The Equalizer' movie, I thought it interesting to have a list of 100 books that one should read before dying. I, like every one else, got on the Web and googled for the list. It seems that there is not a list that every one can agree on. No surprise there. So, I just picked one and here it is:

  • The Time Machine by H.G. Wells     March 11, 2015 Kindle Paperwhite, MOBI format from Gutenberg.org.
  • Moby Dick by Herman Melville       March 17, 2015 Ipad, EPUB from Gutenberg.org
  • The Plague by Albert Camus       March 25, 2015 Kindle Paperwhite, MOBI
  • Gilgamesh, Anonymous
  • Analects, by Confucius
  • The Iliad, by Homer
  • The Odyssey, by Homer
  • The History of the Peloponnesian War, by Thucydides
  • Aesop’s Fables
  • Oedipus, Antigone, and Oedipus at Colonus, by Sophocles
  • The Orestia, by Aeschylus
  • The Republic, by Plato
  • The Nicomachean Ethics, by Aristotle
  • Histories of Herodotus
  • Hortensius, by Cicero
  • The Aeneid, by Virgil
  • The Metamorphoses, by Ovid
  • The Meditations of Marcus Aurelius
  • The Confessions of St. Augustine
  • The Consolation of Philosophy, by Boethius
  • On Loving God, by Bernard of Clairvaux
  • The Mind’s Road to God, by Bonaventure
  • Didascalicon, by Hugh of St. Victor
  • The Summa Theologica (selections are okay), by Aquinas
  • Beowulf, Anonymous
  • The Canterbury Tales, by Geoffrey Chaucer
  • Sir Gawain and the Green Knight, by the Pearl Poet
  • The Cloud of Unknowing, Anonymous
  • The Divine Comedy, by Dante Alighieri
  • The Fairie Queen, by Edmund Spencer
  • The Prince, by Niccolo Machiavelli
  • Utopia, by Thomas More
  • Four Great Tragedies (Othello, Macbeth, Hamlet, & Lear), by Shakespeare
  • Henriad Tetrology (Richard II, 1-2 Henry IV, & Henry V), by Shakespeare
  • Four Great Comedies (Merchant of Venice, Much Ado about Nothing, Twelfth Night, & The Tempest), by Shakespeare
  • Institutes of the Christian Religion, by John Calvin
  • The Temple, by George Herbert
  • Paradise Lost, by John Milton
  • Pilgrim’s Progress, by John Bunyan
  • Tartuffe, by Jean-Baptiste Poquelin Moliere
  • Groundwork of a Metaphysic of Morals, by Immanuel Kant
  • Pensees, by Blaise Pascal
  • Gulliver’s Travels, by Jonathan Swift
  • Essay on Man, by Alexander Pope
  • Candide, by Voltaire
  • Robinson Crusoe, by Daniel Defoe
  • The Federalist Papers, by various authors
  • The Declaration of Independence and the United States Constitution
  • The Wealth of Nations, by Adam Smith
  • Lyrical Ballads (2nd ed.), by Wordsworth and Coleridge
  • Vindication of the Rights of Woman, by Mary Wollstonecraft
  • A Practical View of Christianity, by William Wilberforce
  • Faust, by Johann Wolfgang von Goethe
  • Pride and Prejudice, by Jane Austen
  • Grimm’s Fairy Tales
  • Democracy in America, by Alexis de Tocqueville
  • The Scarlet Letter, by Nathaniel Hawthorne
  • Adventures of Huckleberry Finn, by Mark Twain
  • Leaves of Grass, by Walt Whitman
  • Walden, by Henry David Thoreau
  • Middlemarch, by George Eliot
  • Barchester Towers, by Anthony Trollope
  • Narrative of the Life of Fred D., an American Slave, by Frederick Douglass
  • In Memoriam, by Alfred, Lord Tennyson
  • The Origin of Species, by Charles Darwin
  • Tales of the Grotesque and Arabesque, by Edgar Allan Poe
  • Bleak House, by Charles Dickens
  • Unspoken Sermons, by George MacDonald
  • The Idea of a University, by John Henry Newman
  • The Brothers Karamazov, by Fydor Dostoyevsky
  • Anna Karenina, by Leo Tolstoy
  • Madame Bovary, by Gustave Flaubert
  • Les Miserables, by Victor Hugo
  • Tess of the D’Urbervilles, by Thomas Hardy
  • The Complete Sherlock Holmes, by Sir Arthur Conan Doyle
  • Genealogy of Morals, by Friedrich Nietzsche
  • The Communist Manifesto, by Karl Marx and Friedrich Engles
  • The Cherry Orchard, by Anton Chekhov
  • Rerum Novarum, by Pope Leo XIII
  • Heart of Darkness, by Joseph Conrad
  • Portrait of an Artist as a Young Man, by James Joyce
  • Howards End, by E.M. Forster
  • Civilization and Its Discontents, by Sigmund Freud
  • Orthodoxy, by G. K. Chesterton
  • Fear and Trembling, by Soren Kierkegaard
  • Four Quartets, by T. S. Eliot
  • Brideshead Revisited, by Evelyn Waugh
  • Waiting for Godot – Samuel Beckett
  • Deus Caritas Est, by Pope John Paul II
  • The Lord of the Rings, by J. R. R. Tolkien
  • Death of a Salesman, by Arthur Miller
  • The Cost of Discipleship, by Dietrich Bonhoeffer
  • The Chronicles of Narnia, by C. S. Lewis
  • One Hundred Years of Solitude, by Gabriel Garcia Marquez
  • 1984, by George Orwell
  • Brave New World, by Aldous Huxley
  • The Sound and the Fury, by William Faulkner
  • Silence, by Endo Shusaku
  • One Day in the Life of Ivan Denisovich, by Alexander Solzhenitsyn
  • Complete Short Stories, by Flannery O’Connor
  • The Complete Calvin and Hobbes, by Bill Waterson

    I got the list from the web site http://tinyurl.com/mjzbvsl