THE SQUELCH BURST
a monthly publication of the
STAMFORD AMATEUR RADIO ASSOCIATION
President .......… Andy Laska .............. KA1SLG ........ 531-9493
Vice Pres .……..Fred Cunningham...... K1FC …......... 322-8274
Secretary .....…. Mike Cordelli .....…... N1FOA .…..... 838-3661
Treasurer ...…... Dick Finn .…..............WA1VUU ..... 323-0982
Trustee .......…... Spence Heath ........... W1BWK......... 322-7539
Editors .......…... Marv Fleischman ...... N1AWJ ....….. 438-7889
Mike Cordelli ........... N1FOA .....….. 838-3661
Dick Finn ..................WA1VUU …... 323-0982
Y.O.J.B. Ed..…. Marv Fleischman .... N1AWJ ...….... 438-7889
Circ/Pub..…...... Dick Finn ................. WA1VUU …... 323-0982
Repeaters: W1EE/R........ 146.055 in; 146.655 out (PL. 1Z, 100Hz)
W1EE/R.... 442.125 in; 447.125 out (PL. 2A, 114.8Hz)
Internet Home Page at http://www.qsl.net/ctsara
Yearly membership $20.00 ($ 15.00 for retirees, senior members over 62, $10.00 for full time students, members under 16 years of age and members living over 100 miles from Stamford; $20.00 for family memberships.) This includes a copy of the club bulletin and a copy of the club roster.
Send your dues, membership applications, etc. to the club Treasurer, Dick Finn, WA1VUU, 27 Ivy St., Stamford CT 06902.
Non-commercial ads are printed in the SQUELCH BURST on a no charge basis, club members only. Send your ads for Ye Olde Jonque Boxxx and articles for the SQUELCH BURST to Marv Fleischman, N1AWJ, P.O. Box 113, Ridgefield, CT 06877-0113, or e-mail to .
Unless noted, meetings are held on the first Thursday of every month in the 4th floor cafeteria of the Stamford Government Center, Tresser and Washington B'lvds., Stamford, CT. Meetings start at 8:00 P.M. Free parking in the Government Center garage with the entrance on Washington B'lvd.
The Stamford Amateur Radio Association is a tax exempt organization under section 501 (c) (3) of the Internal Revenue code.
May 2002
EMPIRE SLOW SPEED NET
Join the Empire Slow Speed CW Net every evening on 3590 KHz at 6PM local time. CW speed is between 6 and 8 wpm. A great way to improve your CW proficiency and learn net operation. Joe, W1LUH is one of the rotating Net
Control stations.
ASK ELMER
Dear Elmer
What useful things can be done with an Oscilloscope in both the ham shack and also building, diagnosing and checking equipment?
Signed C. R. O'Scope
Dear CR,
This is a subject that one could, and have written many application notes and books on over the years. It's interesting that this instrument was initially thought of as having an extremely limited use (primarily only in some scientific and television applications). Wow, were they wrong! The Tektronics Corp. had built itself initially on this instrument alone. To those who are unfamiliar with an Oscilloscope, I will describe the instrument and its basic function. Most of us are familiar with a voltmeter, as a basic measuring instrument. A voltmeter measures the voltage level at a point in a circuit at any fixed instant of time. The reading does not indicate what the voltage was at an earlier time, or how it varies with time. You could write down successive measurements and then graph them to obtain this information. If the voltage was varying at a high rate, you could not keep up with the changes, no matter how fast you could write. Something like trying to copy CW at 30 WPM…. Your hand-ear coordination is just too slow. You need some help. Here is where the Oscilloscope comes in. The display on the oscilloscope consists of a screen which generally displays the measured voltage as a point (of illumination) on the vertical axis while this point of light is being swept across the screen at a defined rate of speed. What I mean as a defined rate of speed is the point of light (lets shorten this to and call it a “Beam” to save my typing) is moved across the screen at a very constant and repetitive 1 screen division per (centi, milli, micro, nano) second. Now, if the voltage varies during the time the beam is sweeping across the screen, you will see this variation. Due to the materials used to display the Beam in the Oscilloscope, and the persistence of vision of the eye, and if the voltage variations are repetitive, then you have a real time graphical representation of the voltage verses time. This is the basic Oscilloscope. There are controls to vary the speed of the Beam and the ability to synchronize the Beam with the incoming signal, and to adjust the sensitivity of the instrument to give it maximum flexibility, but these don't change its basic function.
Now that we know how the instrument works, we will discuss some of its applications both in the shack and on the test bench, without going into the details of the test procedure. The most common application in the shack is a modulation monitor. The Oscilloscope can display the RF envelope and the modulation pattern of your transmitter. Using a technique known as a “Trapezoidal pattern”, you can monitor the depth of modulation of an AM transmitter. You can, with a wideband Oscilloscope, determine of there is any distortion of your RF carrier and see if there is any spurious signals being generated by your rig. With the proper auxiliary circuitry, you can use the Oscilloscope as a spectral display, which shows the frequency and relative strength of the signals seen by your receiver. This is only the “tip of the iceberg”, as the instrument can be used wherever a voltage verses time display or voltage display in real time is needed. By the way, I always mention Voltage measurement, but you can, just as well, substitute Current or Power for Voltage. On the test bench, the primary function of the Oscilloscope is to determine of a circuit is operating properly by observing the voltages within the circuit. You can measure the signals amplitude, frequency, phase, duty cycle and period, just to mention a few. The following are a few references which can assist you in use of the Oscilloscope (besides many sites on the Internet):
ARRL ed.; “Handbook for Radio Amateurs”; ARRL Pub.; 2001
Rider, Uslan; Encyclopedia of the Cathode Ray Oscilloscope and their Uses”
“Complete Book of Oscilloscopes”; Tab Pub.; 1992
Sams, H. W.; “Oscilloscope Guide”; Prompt Pub.; 2001
Well, CR, this was but a very brief description of the instrument's uses which is limited only by your imagination.
73,
Elmer
Send your questions to “ASK ELMER”, c/o Marv Fleischman, N1AWJ, PO Box 113, Ridgefield, CT 06877-0113 or e-mail them to
VE EXAMS
The next regularly scheduled SARA sponsored Amateur Radio License examinations will be held on Saturday, May 11. They will be held in the Stamford Government Center on Tresser and Washington B'lvd's in Stamford. Check-in is at 9:30 AM with the examinations starting at 10AM. The fee for the examination session is $10, and we would appreciate a check made out to the ARRL-VEC (cash is accepted, but a check is preferred). Pre-registration is not required. Bring 2 pieces of ID, one being a photo ID (Drivers license, etc.) For those seeking upgrades, bring your current license and a photocopy of your current license to attach to the NVEC605 form, as well as any CSCE's that you may have showing any credit for exams passed in excess of your current license.
May 2002
MINUTES OF THE MEETING OF 4 APRIL, 2002
No guests, no new members, no call sign changes this month.
Committee reports: Jim reported the class has been a success, they will have a special VE session once the class is over for the people who took the class.
VE- Next session Saturday, May 11th, 9:30 check in time at Government Center in Stamford. Fee is $10.00 for the session. Bring youe License, a copy of your license radio) another form of ID, and a filled out 605 form.
Possible Upcoming Public Service events: These are possible because we haven't been contacted by them all yet: Cancer Walk June 2, Mayors Cup June 9, Denmark Race in September.
Emergency: We will be exercising our call out list soon.
Tech: The moving of the repeater was set to be completed after the writing of these minutes.
Old Business: The Slow Speed CW net on 2 meters is progressing with the completion of several of the kits. Marv has plans available for those who want to connect (Below) a Heath Keyer. The net will start up on the first Sunday in May at 9pm local right after the regular net.
