January 2003
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 .......…... Jim Markus .............. N1ZFS ........... 316-8585
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/w1ee/ctsara.htm
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 n1awj@
att.net.
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.
PRESIDENT'S MESSAGE
Happy Holidays to all. As many of you I have been under the weather for a while
and finally got released from the hospital the day
before Thanksgiving. I came home from NY Presbyterian in a stretch limo, wearing
a pair of summer shorts, a hospital gown and bare
feet, in a snow storm. Walking to the limo, no one on the
streets of Manhattan gave me a second glance.
I would like to thank all of you that called or sent cards, it's uncanny how
they arrived just when I needed a pick me up the most.
I am trying to get the ball rolling on the repeater replacement, by the time you
read this it should be ordered and being built. I
have also talked with K1FC and N1AWJ about getting the machine back up at higher
power level.
Happy New Year, and I hope to be strong enough to attend the January or February
meeting
Andy.
REPEATER COMMITTEE MEETING
Due to the inclement weather on December 5, our meeting/holiday party had to be
cancelled, therefore there is no meeting minutes to
report. We hope that the weather will be more cooperative for the January
meeting. On Tuesday December 10, the Repeater Committee
met at Andy's (KA1SLG) house. Present were Ernest, KA1NGG, Mike, N1FOA, Andy,
KA1SLG, Fred, K1FC and Marv, N1AWJ. The meeting
centered on the selection of the repeater and accessories as well as the type of
duplexer to purchase. The committee reviewed
several manufacturers of repeaters and selected a VHF Hi Pro Repeater by
Maggiore Electronic Lab. The repeater's output power is 35
Watts. We have not selected a power amplifier as yet, but plan to in the near
future. The repeater comes complete with a
controller (with full autopatch, speed dialing, voice ID and PL decoding
functions) but requires an external power supply. We
selected the MFJ 40A switching power supply for its compact size, low weight and
reliability. Purchase of the repeater and duplexer
will have been made by the time you read this report. A full report on the
repeater will be made at the January meeting.
Marv, N1AWJ
ASK ELMER
Dear Elmer,
All of the radios that I have use a Phase Locked Loop Frequency Synthesizer for
tuning. I can easily understand the crystal
oscillator controlled radio, but how can a single quartz crystal produce all of
the discrete frequencies needed to tune my radio.
Signed Puzzled.
Dear Puzzled,
The principals of the Frequency Synthesizer were developed early in the 1950's.
Over the years they have been refined and appear in
many, if not most, of the communications and entertainment devices we use today.
The basic principal on which the Phase Locked Loop (PLL) Frequency Synthesizer is bases upon is signal feedback, comparison and
error correction. Below is a block diagram of a simple
PLL Frequency Synthesizer.
To understand its operation, we must understand the operation of each block
independently, and then as a system. The first block we
will discuss is the “Voltage Controlled Oscillator” (VCO). This is a free
running variable frequency oscillator operating at the
desired frequency range. As an example, if you wanted to operate on the 15 meter
band, this oscillator would have a frequency range
of 21 MHz to 21.45 MHz. The way the frequency would be varied is with an
external voltage using a varactor, rather than a
mechanical variable element (such as a variable capacitor or inductor).
The oscillator would be defined by it's “Transfer Characteristic” which has
the units of MHz/Volt. As an example, the 15 meter unit
might have a transfer characteristic of 0.45 MHz/V. This means that 1 volt will
change the oscillators output frequency over the
full 15 meter band. The next block is the “Variable Ratio Frequency Divider”.
This is the block that controls the tuning of the
entire synthesizer. We won't go into details of how a divider works, but the
divider is a digital circuit which is capable of
dividing the frequency of the VCO by any number (including a fractional number
like 1/213.5). The division ratio is selected by the
tuning dial of the radio. Instead of it being marked in division ratios, it is
marked in output frequency. The next block is the
“Phase Comparator”. The circuit of this block can be similar to a diode
balanced mixer or a digital circuit with a similar
function. The purpose of this block is to compare the phase difference between 2
frequencies and produce a DC voltage proportional
to the frequency and then the phase difference. Its transfer characteristic is
in Degrees/Volt when the two frequencies being
compared are within 1 Hz of each other. The “Reference Oscillator” block is
generally a precision crystal oscillator at some
sub-multiple of the Synthesizers output frequency. Its frequency is chosen so
that the demands on the variable ratio frequency
divider are kept to a minimum. As with anything in electronics, compromises have
to be made between the complexity of the frequency
divider and the output frequency of the reference oscillator. For our discussion
we will not go into the details of the
compromises, as the choices will be left to the system designer. The most
important requirement for the reference oscillator is
that it be very stable and its output signal have a very low phase noise. We
hear the term “phase noise” frequently, but many do
not understand what it is and why is it important. Without going into a very
long and overly technical discussion, all electronic
components have associated with themselves electrical noise being generated by
the random motion of electrons. In oscillators, this
noise modulates (like in your FM and AM transmitter) the output signal in a
random fashion. The ideal oscillator would
Have an absolute unvarying output frequency. Phase noise FM modulates this
signal causing it to jump around in a random fashion.
The greater the phase noise the more the frequency jumps around. Intuitively,
you can see that if the frequency jumps around,
reception and demodulation of the signal to obtain its message becomes
increasingly difficult. Ultimately, if the phase noise is
great enough the signal disappears into the noise and cannot be recovered. This
is rarely the case for amateur communications
except in EME and other weak signal transmissions. Needless to say, the lower
the phase noise the better the signal. One
characteristic of phase noise is that when you frequency multiply a signal, you
also multiply its phase noise proportionally. This
is one of the considerations in choosing the reference oscillator frequency for
a synthesizer. The last block we will discuss is
the “Low Pass Filter”. This is a very standard resistor capacitor low pass
filter circuit, though in some implementations it can be
an electronic filter using an operational amplifier. Its function is to remove
any of the high frequency noise components from the
output of the phase detector, as well as control the response speed of the
system to external noise, and other instabilities.
Without this filter, the circuit would probably be very unstable. A good way of
visualizing the function of the filter, is to think
of a weight, at the end of a spring hung from the ceiling of your room. If
you
were to pull down on the weight and release it, it
would oscillate up and down for quite some time. If there were no losses in the
spring and no air friction, the weight would
oscillate forever. If, you would do the same experiment in a room filled with
motor oil, the weight would not oscillate forever,
but would settle down fairly rapidly. The low pass filter acts like the room
filled with motor oil, to get the system to settle
down to its steady state condition rapidly, and essentially stay there until
something pulls the weight again. The only other
item I wish to mention is that strange symbol (two parallel lines) at the output
of the VCO and connected to the frequency divider.
This is the symbol of a signal sampler. Its function is to sample a small
portion of the output signal and send it to the frequency
divider.
Well Puzzled, I think you will have to remain so until the next issue of the
SQUELCH BURST.
Until then,
73 and a Happy New Year!
Elmer
Send your questions to “ASK ELMER”, c/o Marv Fleischman, N1AWJ, PO Box 113, Ridgefield, CT 06877 or e-mail to [email protected]. WE NEED ELMER QUESTIONS !!!!!!!!!!!
LICENSE EXAMINATION SCHEDULE
For 2003
Unless otherwise notified, Amateur Radio License examinations will be held at
the Stamford Government Center on Tresser and
Washington B'lvd's on the following dates:
Saturday, February 8 at 9:30 AM
Saturday, May 10 at 9:30 AM
Saturday, August 9 at 9:30 AM
Saturday, November 8 at 9:30 AM
Pre-registration is NOT required. Walk-ins are encouraged.
The fee for the test session remains at $10, and we would appreciate a check
(rather than cash, though we will accept cash) made out
to the ARRL/VEC. Bring 2 forms of ID, one being a photo ID. Those who are
licensed and are upgrading, bring a photocopy of your
current license which will be attached to the NVEC-605 form. Bring any CSCE's
that you may have indicating any test elements passed.
TREASURER'S REPORT AS OF 15 DECEMBER 2002
INCOME EXPENSE
Dues 20.00 440 rptr. 50.00
Reptr.Fund 410.00 Postage 37.00
Int. 4.59 Phone 25.70
_______ _______
Totals $434.59 $112.70
Balances: Checking-$983.12 Savings-$3,486.72
De WA1VUU
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.
YE OLDE JONQUE BOXXX
ICOM IC-2AT 2m HT w/Charger, Batty., & SS-32MP micro-min. CTCSS Encoder
kit, VGC, $100; Simpson 260 VOM, VGC, $50.
Call Geoff, N1CAT, (203) 966-7444 evenings
HALLICRAFTER SX-28A RECEIVER, recapped, $275. Works good.
Call Joe, N1GWO, (203) 322-4061 Evenings
PARTS GALORE- Xerox 3000 Word Processor (antique) w/transformer,
p/s, etc., connection to Diablo printer. FOR FREE!!! Take it away!
Call Mike, KA1VWP, (203) 838-8089
AOR 1000 XLT, 1000 Channel HH Scanner, 5KHz to 1.3 GHz cont. coverage. Exc.
cond. $ 275.
Call Rick, N1LYK, (203) 531-1756
YAESU FT-757 GXII, HF Rig, FP 757 HD Power Supply, FC 757 AT Tuner
and MD 1B8 Desk Mike.
Call George, N1HIX, (203) 357-1879
Mac Laserwriter printer, best offer.
Call Jeanine, KY1Q, (203) 324-6865
FatMac Computer w/ 1Meg Ram, Free!!!; FOR PARTS..Olevetti Accounting Machine.
FREE!!!!! Take it away!!!
Call Marv, N1AWJ, (203) 438-7889
HD-73 ROTOR w/CONTROL & CABLE, $50; Cushcraft 10-40M Vert. Ant., $15;
Heathkit Station Monitor Mod. 614, $50. 2 South Bend 7.5 HP
Go-Cart Engines. Call for Info.
Call Irv, N1ATS, 348-3425 or e-mail [email protected]
2M 30W AMPLIFIER, $25; 6M Amplifier, 10W in 150W out, $175: AM6155 2M SSB
Amplifier, 8930 Tube based, Cavity Tuned, 400 W Out (not
cont. duty) $325.
Call Andy, KA1SLG, (203) 531-9493
MFJ ANTENNA TUNER A-1 Cond. $100; Cushcraft R4 Ant , New, $25; ¼ ? Mag. Mt.
Ant., $12; ? ? Mag. Mt. Ant, $15, ? ? Trunk Mt. Ant.,
$10; Measurements Grid Dip Meter, $25; HP Signal Gen.; $15; Code Pract. Mach.,
$15
Call Milt, K2DLT, (203) 324-2723
MICROTEK SCANMAKER, Flat Bed Scanner Mod. E3 w/cables, software and ISA SCSI
card. FREE to a good home
Call Dick, WA1VUU, (203) 323-0982
Send all your ad's for YE OLDE JONQUE BOXXX to Marv Fleischman, N1AWJ, PO Box
113, Ridgefield, CT 06877. E-mail to
[email protected]. Ad's must be in by the meeting
night of the month prior to the publication. (December meeting for January
publication)