Speaker Notes
July 2007
| Module-1 | Module-2 | Module-3 | Module-4 | Module-5 | Module-6 | Print Version |
| Slide Number |
Footnote |
| 1-2 |
The reference to Pages 23 through 64 is to the
Gordon West General Class Study guide, 7th edition.
This guide is available from HRO
either in the store or order on-line, or through the W5YI VEC
http://www.w5yi.org
Cost is $21 plus tax and shipping.
This guide is not only a great aid to passing
your test but will remain a valuable desk reference long after
you receive your license.
|
| 1-4 |
CSCE: Certificate of Successful Completion.
This document is sort of like a “receipt” to prove that
you passed a particular element. It’s main purpose is to serve
as proof of completion if a candidate wishes to upgrade before
his permanent license is issued.
At the current time, VECs and FCC are processing
license applications in less than two weeks.
Once you have the permanent “hard copy” of your license
the CSCE has little importance.
|
| 1-8 |
Once your license has been “Granted” (FCC speak
for Issued) you don’t need the AG.
This is not the same as being “Filed” as in answer D. In
reality, the difference between “Filed” and “Granted” is usually
only a day or two but be careful;
sometimes things will hold up an application, such as a
previously pending
application. Your
license is not “Granted” until the ULS database says it is.
|
| 1-15 |
The formulas at the top are useful in converting
frequency to wavelength.
For example, if the question asks:
Which of the following frequencies is in the 12
meter band?
A: 3.940 mHz
B: 12.940 mHz
C: 17.940 mHz
D: 24.940 mHz
You can divide each into 300 until you get a
reasonable answer. For example, 300/24.940 = 12.03..Close
enough?
The next line looks like a phone number.
I did that to make it easy to memorize.
Here’s what it does:
.707 (point seven oh seven) is the number you use
to convert a peak AC voltage to RMS (Root Mean Squared).
This needs to be done since an AC voltage can not be used
in a DC calculation.
Converting it to RMS first “makes the wave stand still” so it
can be measured. Read
the questions carefully as they sometimes ask for Peak-to-peak
voltage. RMS
calculations are made on Peak voltages only!
Example: What is the RMS value of a peak-to-peak AC
voltage of 5 volts?
Answer: divide 5 by 2 and then multiply 2.5 times .707.
1.77 volts RMS is the answer.
468 is a “constant” used to calculate the length
of a half-wave dipole.
Divide 468 by the frequency in mHz.
For example: What is the length of a half-wave dipole cut
for 7.1 mHz? Answer:
468/7.1=65.9 feet.
1005 is used in the same way to calculate the
length of the wire needed for a “quad” antenna. The question
might ask you “How long is one side of a quad loop cut for 7.1
mHz? The answer is
1005/7.1=141.5 (feet) divided by 4=35.4 feet.
The bottom collection of formulae are all the
ones you need for the test even though there are actually 12
variations. Memorize
these and you will have it made.
More on Ohms law later.
|
| 1-16 |
A chronological guide.
The original Ham bands were those shown on the
left side of the screen in white.
Notice that they all were related harmonically.
This was to simplify construction
since the operating frequencies were determined by crystals.
In 1953 15 meters was added.
It was also harmonically related.
In 1967 there were five classes of license;
Novice, Technician, Conditional, General and Extra.
There was very little incentive for a General to upgrade
to Extra since the only thing you got for it was the right to
request a one by two callsign such as W6CO. The FCC in an effort
to get Generals to upgrade, thus improving their skills, decided
to take away blocks of frequencies for everyone except Extras.
Once we got over the outrage, we bit the bullet and
upgraded getting our frequencies back.
You can still see those bands that were affected today:
They are the ones stating with nn025.
Notice that only 80, 40, 20 and 15 have the missing
blocks. The FCC left 160
and 10 alone since they were too lightly used to apply
“incentives” to.
The bands shown in “rust” color were added during
a WARC (World Amateur Radio Conference) in 1979.
Incentive licensing had been in effect for more than ten
years and was not needed any more.
Notice that the “WARC” bands are quite narrow
compared to the older bands.
30 meters is so narrow that only CW is permitted. No
phone and no image. It is also a shared band so power is limited
to 200 Watts max.
Finally in 2003 60 meters was opened up for
shared use under very strict operating standards.
|
| 1-17 |
These are the bands and the corresponding
frequencies. The
question pool asks about those shown in green.
For some reason they skip over the ones in white although
you need to know them to operate properly.
Get a copy of the band plan and keep it on your operating
desk.
|
| 1-19 |
Thinking
outside the box: The QPC
seems to have overlooked the 60m band where all amateurs have
equal privileges. No
matter, the above information is what the
examination requires.
|
| 1-23 |
It is probably easiest to remember that 1500
Watts PEP is the legal limit on all bands except:
30 meters (200 Watts) and 60 meters (50 Watts).
In all cases however, the operator has the responsibility
to use no more power than necessary to maintain the contact.
|
| 1-25,29 |
10 meter repeaters can be found between 29.5 and 29.7
mHz. This sub-band is open
only to General class and above operators but Technician class
operators can use the facilities in a cross-band configuration when
the repeater has a General class or higher operator at the control
point. The Technician class
operator can either transmit on 2-meters, where he does have
privileges or on Echolink.
In either case it is the responsibility of the control operator to
be present when ever the repeater is in operation.
|
| 1-30 |
Amateurs are allowed 1500 watts PEP with a few
exceptions. There are
only a few bands where power restrictions are universal.
Only the 30m question (200 watts)
will be on the test.
Other power restrictions are based on operating class
(Novice/Technician) and location (near the White Sands Missile
Test Range or the Canadian border).
§97.313 Transmitter power standards.
(a) An amateur station must use the minimum
transmitter power necessary to carry out the desired
communications.
(b) No station may transmit with a transmitter
power exceeding 1.5 kW PEP.
(c) No station may transmit with a transmitter
power exceeding 200 W PEP:
(1) On the 10.10-10.15 MHz segment; (2) When the
control operator is a Novice Class operator or a Technician
Class operator who has received credit for proficiency in
telegraphy in accordance with the international requirements; or
(3) The 7.050-7.075 MHz segment when the station
is within ITU Regions 1 or 3.
(d) No station may transmit with a transmitter
power exceeding 25 W PEP on the VHF 1.25 m band when the control
operator is a Novice operator.
(e) No station may transmit with a transmitter
power exceeding 5 W PEP on the UHF 23 cm band when the control
operator is a Novice operator.
(f) No station may transmit with a transmitter
power exceeding 50 W PEP on the UHF 70 cm band from an area
specified in footnote US7 to §2.106 of the FCC Rules, unless
expressly authorized by the FCC after mutual agreement, on a
case-by-case basis, between the District Director of the
applicable field facility and the military area frequency
coordinator at the applicable military base. An Earth station or
telecommand station, however, may transmit on the 435-438 MHz
segment with a maximum of 611 W effective radiated power (1 kW
equivalent isotropically radiated power) without the
authorization otherwise required. The transmitting antenna
elevation angle between the lower half-power (-3 dB relative to
the peak or antenna bore sight) point and the horizon must
always be greater than 10°.
(g) No station may transmit with a transmitter
power exceeding 50 W PEP on the 33 cm band from within 241 km of
the boundaries of the White Sands Missile Range. Its boundaries
are those portions of Texas and New Mexico bounded on the south
by latitude 31° 41' North, on the east by longitude 104° 11'
West, on the north by latitude 34° 30' North, and on the west by
longitude 107° 30' West.
(h) No station may transmit with a transmitter
power exceeding 50 W PEP on the 219-220 MHz segment of the 1.25
m band.
|
| 1-36 |
This is one of the basic rules for operating on any
band.
|
| 1-38,40 |
This band is only 50 KHz wide so Phone and broad
data is not permitted.
|
| 1-48 |
This band is so narrow and shared with other
services that it is channelized.
Very strict controls are in place restricting type of
emissions.
|
| 1-54 |
The reason for this is because we are restricted
to only 50 Watts ERP (Effective Radiated Power).
If you use a dipole, which is considered a “Unity Gain”
antenna, your PEP and your ERP will be the same.
If you use a gain antenna however, such as a Yagi, your
ERP will be your PEP multiplied by the gain.
You must then reduce your PEP so that your ERP is back
within limits. You must note this in your logbook, which becomes
a permanent part of your station records.
|
| 1-60 |
As a general rule, if you can hear them, they
will be able to hear YOU.
It’s best not to use the frequency if you can copy other
signals on it.
|
| 1-63,64 |
Notice the absence of decimal points in the
frequency choices. For
the purposes of this course, both forms are the same but if you
want to convert to wavelength, by dividing into 300, put the
decimal where it belongs first. (after the first digit)
|
| 1-72 |
Don’t be fooled.
You may be used to hearing CB operators on our 10 meter
band. They aren’t
“sharing” the band, they are operating illegally!
|
| 1-76 |
It may be difficult to find printed guidelines
indicating the “DX window”.
As a rule of thumb, these exist primarily in the bottom
25 kHz of the HF bands with the exception of 3790 to 3800 in the
80 meter band. If you
confine ragchewing to the General class portion of any band you
won’t be in the DX window.
|
| 1-79 |
This is a very unlikely circumstance, but it’s
the answer they want.
|
| 1-81 |
There are much better reasons for keeping a log
than in the previous question, and they are all personal
reasons. If you
participate in exchanging QSL cards, a log is vital since it
contains vital information you will need to verify a contact
sometimes years after the fact.
Logs also serve as “journals” and can be fun to review
years after they are closed.
Ignore the green “happy face”. Its used in the
“live” course to signal a change in topic.
|
| 1-97 |
The retransmission of a space shuttle or ISS
traffic would be done by a bulletin station.
This would be one example of an allowed “broadcast” or
one-way transmission which would otherwise be illegal.
Remember, one-way transmissions are allowed when they are
“of general interest to the amateur radio community.” 97.3(a)10
|
| 1-99 |
Read about space stations and Amateur Radio at
www.amsat.org. AMSAT is a
very active group of Amateur Radio operators who provision and
operate repeater and telemetry equipment on satellites. Control of
this equipment is confined to “secret codes” for security reasons
and is the only type of secret code permitted
|
| 1-101 |
CW operators use abbreviations extensively to
speed up the conversation. You will also hear DX CW using
something called “Cut numbers” to save time.
All perfectly legal.
|
| 1-103 |
This is done quite often.
There are “Swap nets” where amateur gear is listed for
sale. It is considered
poor practice to conduct the actual sale on the air, rather get
the other party’s email address or telephone number and finalize
the deal off the air.
|
Module-1 (continued) Go back to top
| Slide Number |
Footnote |
| 1-105 |
This is a condition set forth by the FCC as part
of the “punishment” of a licensee who’s license has been
revoked. He is not
permitted to use Amateur Radio under any circumstances.
|
| 1-111 |
Third party agreements and reciprocal licensing
agreements are published on the web.
You should print out this information and keep it with
your operating aids in your station.
|
| 1-133 |
FYI:
On HF phone nets,
“Break-Break” usually indicates priority traffic.
A triple break as in C: above would indicate emergency
traffic.
|
| 1-137,139 |
The key to getting along in confined spaces in to
act in a non-confrontation manner in all things. Don’t let
road-rage type behavior get started on the ham bands.
|
| 1-145 |
Helpful hint:
Q-signals often includes abbreviations.
QRP stands for “Reduce Power”
There are many hams who enjoy QRP operation and
they even have contests to see how far they can make a contact
(miles per milliwatt).
Some consider 5 Watts to be the upper limit of QRP
operation. Give it a
try, you may be amazed at what you can accomplish with just a
fraction of a Watt.
|
| 1-147 |
Voice Operated (VOX) headsets and speaker/mikes
are available. These
permit hands-free operation by detecting the voice of the user
and automatically activating the push-to-talk (PTT).
Most of these unit offer a way to switch to manual
operation to eliminate falsing (inadvertent transmissions) in a
noisy environment. They
also generally offer some means to control the sensitivity
(gain) of the VOX circuitry.
Better units include VOX delay to eliminate falsing on
pulse noises and anti-VOX to prevent received audio from
activating the transmitter.
|
| 1-165 |
This is the appearance of an AM signal on a
spectrum scope. There is
a carrier in the center that uses power but contains no
information (it can be used for tuning).
Each of the two sidebands (upper and lower) are identical
but inverted. HF amateur
communications are generally on a single sideband (SSB) by
suppressing the carrier and opposite sideband.
This is more efficient by using less bandwidth and power
is not wasted transmitting a dead carrier and duplicate
sideband.
Because of radio design simplicity, the
convention has been to use lower sideband (LSB) below 14 MHz and
upper sideband (USB) above 14 MHz.
|
| 1-178 |
Make a mental note:
These 3 bands, (the lower 3) use Lower Sideband, all
others use Upper Sideband.
A recent exception is 60 meters which also uses Upper
Sideband. On 60 meters
you MUST use upper sideband.
All other bands, the sideband you use is recommended, not
required by the rules.
|
| 1-180 |
Once again, this is a STRONG recommendation, not
the rule.
|
| 1-182 |
On CW, “de” is the abbreviation for “from”.
CW ops use many other abbreviations as well.
|
| 1-186 |
In matching one tone to another (yours versus
his) as you get close to being matched you will notice a
harmonic caused by the two audio tones mixing.
As you get closer and closer to matching the harmonic
will get lower and lower in frequency until it gets so low you
can’t hear it. This is
“zero beat”.
|
| 1-192 |
In CW each Q-signal will have two meanings.
If QRS? The meaning is “Shall I send slower?”
Without the question mark it means “please send slower”.
|
| 1-238 |
In
fact, the
code is referred to as “Varicode”.
|
| End Notes for Module-1 |
Module-2 Go back to top
| Slide Number |
Footnote |
| 2-3 |
Generally, the reference
to “property” is meant to be homes and other buildings.
How about a car?
A bicycle? You decide.
|
| 2-6 |
Rule of thumb: In a
genuine emergency, that is an immediate danger to human life or
real property, pretty much anything goes.
|
| 2-27 |
The key points are the D,
E and F layers. The F
layer splits and becomes F1 and F2 with the additional energy
from the daytime sun.
The D and E layers disappear at night without the sun’s energy.
The D layer absorbs most RF power, particularly at low
frequencies. The other
layers will reflect RF energy.
The higher the layer, the further the contact possible.
Propagation conditions
are a balance between the D layer absorption of lower
frequencies and the reflection of the higher frequencies by the
upper layers. As more of
the sun’s energy (primarily electromagnetic and particle
emissions) strikes the ionosphere, all the layers grown in size
and density. The D layer
will absorb more low frequency RF and the upper layers will
reflect more high frequency RF.
This creates a window of frequencies above the Lowest
Usable Frequency (LUF) and Maximum Usable Frequency (MUF) that
will work for long distance communications.
Sunspots provide huge
amounts of energy to reflect radio waves in the ionosphere and
are especially important in the upper bands.
Sunspots occur in 11-year cycles of high and low
activity.
For additional information refer to Page 70 in the Gordon West Study Guide. |
| 2-31 |
The illustration on slide
59 can be of help understanding this.
There are only two questions on the test asking about
maximum distances per region.
The other question deals with the E-region.
|
| 2-33 |
This is because at noon
during the summer, sunlight (and ultra violet radiation) will
be at its maximum intensity.
It is the effect of this radiation that changes the altitude of the
F layers.
|
| 2-34 |
Refer to the
illustration on Slide 34: Note that the altitude and angle of
refraction varies with frequency.
Generally the higher frequencies will be refracted at
higher altitudes and at shallower angles.
If the frequency is high enough, it won’t be refracted
enough to arrive back on the surface.
The highest frequency that can be refracted is the
“critical frequency” and generally the Maximum Usable Frequency
(MUF).
If the angle if the wave
is too steep, it will continue into space.
The steepest angle that will be refracted back to the
surface is the “critical angle”.
Think of skipping a stone
on a pond. If you hit the water at just the right angle, the
stone will skip multiple times.
If the angle of your toss is too oblique, the stone will
penetrate the surface of the water and sink without skipping.
|
| 2-36 |
Notice the answer says
“return a radio signal to earth”.
Signals may “bounce” or “skip” but they are not
“reflected”. The correct
term is “refracted”.
|
| 2-44 |
On HF, beacon stations
can be found on specific frequencies on 20 through 10 meters.
See this URL for complete details: http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=1112
|
| 2-46,48 |
Do you remember the
conversion formula? mHz
to meters: 300/f(mHz).
Choose the answer that comes the closest. E.g. 300/22=13.6 (14)
Choose 15.
|
| 2-54 |
This is the second of two
questions referring to the maximum distance along the earth’s
surface. See the
illustration on slide 59.
|
| 2-58 |
They are in alphabetical
order but what happened to A, B, and C?
They are atmospheric, not Ionospheric. In Ham radio we
only care about D, E and the F layer which splits in two during
the day. See slide 27
for the illustration.
|
| 2-61,63 |
The Darn D layer is
Disruptive During Daylight!
|
| 2-81 |
An Azmuthal map is a map
projection centered on a particular location, used to determine
the shortest path between points on the surface of the earth.
From this map, centered on Seattle,
it can be seen that San Diego is 165 degrees, Hawaii
about 230 degrees and Anchorage, AK will be about 325 degrees
for the shortest path.
These bearings will likely be different than those from a
standard Mercator projection because they account for the
earth’s curvature.
|
| End Notes for Module-2 |
Module-3 Go back to top
| Slide Number |
Footnote |
| 3-5 |
This is the appearance of
an AM signal on a spectrum scope.
There is a carrier in the center that uses power but
contains no information (it can be used for tuning).
Each of the two sidebands (upper and lower) are identical
but inverted. HF amateur
communications are generally on a single sideband (SSB) by
suppressing the carrier and opposite sideband.
This is more efficient by using less bandwidth and power
is not wasted transmitting a dead carrier and duplicate
sideband.
|
| 3-10 |
Since it combines
signals, the balanced modulator is a type of mixer. It’s
the “balancing” that removes the carrier.
Some radios allow the carrier to pass through (for CW or
AM phone) by “un-balancing” the modulator.
|
| 3-18 |
In this illustration you
can see why SSB is the narrowest of the choices.
A phase-modulated or FM signal would be at least as wide
as the carrier and both sidebands shown here.
A double sideband signal,
(they do exist) would use both sidebands shown above but the
carrier would have been removed.
|
| 3-22 |
A speech processor does
not necessarily improve your signal.
Improperly adjusted, it can ruin it!
|
| 3-26 |
ALC stands for Automatic
Level Control. Properly
adjusted, your ALC indication on your meter should show little
or no motion.
|
| 3-28 |
…and more bandwidth can
cause interference to adjacent stations,
|
| 3-33 |
Illustration on slide 33:
Two tone audio tests are
used on an oscilloscope to test proper linearity.
The pure tones fed in will give you a stable picture on
the scope if the amplifier is properly adjusted.
The lower image shows a signal with some noise that it
also overdriven (over modulated) and is clipping or flat
topping. Any two audio tones may be used, but they must be
within the transmitter audio passband, and should not be
harmonically related.
Speech Processors are
used to keep input audio close to a perfect level for 100%
modulation. If they are
not adjusted properly, they can cause the distortion seen here.
Overdriving causes very distorted audio and no additional
power output.
|
| 3-38 |
This is a current model
Tektronix oscilloscope.
It has four signal inputs along the lower right edge and can
display the waveforms from those inputs.
There are three main sections to the right of the screen;
vertical, horizontal and trigger.
The horizontal and vertical controls adjust how the
waveform appears on the screen by adjusting the horizontal and
vertical amplifiers. The
trigger controls allow the oscilloscope to synchronize to
external events.
|
| 3-42 |
The term “monitoring
oscilloscope” simply refers to the way the oscilloscope is used.
It is connected into the transmitter’s output during
operation in order to evaluated the transmitted signal.
It’s just an oscilloscope.
|
| 3-50 |
Self oscillations can
occur within a vacuum tube and are caused by the internal
components of the tube being in proximity to one another. If
allowed to continue, self oscillations will not only distort the
signal but can actually damage the tube.
|
| 3-58 |
A simple formula for
calculating the total bandwidth of an FM signal:
The sum of the deviation (in kHz) and the highest
modulating frequency, times 2.
In this example, 5+3 x 2= 16
|
| 3-61 |
Looks tough right?
But it’s easy. Find the ratio of the modulated oscillator
to the transmitters frequency: 146.52/12.21=12.
Now apply that ration to the 5,000 Hz deviation:
5,000/12 = 416.7 Hz
|
| 3-71 |
Peak Voltage = ½
peak-to-peak or 100 Volts.
Now multiply 100 x .707 to convert it to RMS.
100 x .707 = 70.7 Volts. Now square that by multiplying
70.7 times itself. 70.7
x 70.7 = 4998.5. Divide
that by 50 and you get 100 Watts (rounded).
Why?
Here’s the Ohm Law equivalent: P = E2 /
R Review Slide 15 in Module-1, and Slide
3 in Module-4. We'll see this same formula used again.
|
| 3-72 |
There are three key
voltage measurements, RMS (Vrms), Peak (Vpk) and Peak to Peak (Vpp).
The Peak voltage is relative to ground.
RMS or Root Mean Square is more of an “average” voltage
over the duration of the AC cycle.
RMS voltage is calculated by multiplying 0.707 times the
peak voltage. The Peak
to Peak voltage measures from the peak of the positive swing to
the peak of the negative swing.
The 120 volt AC line
voltage in the wall is a peak value.
That means the RMS voltage is 85 volts and Peak
to Peak is 240 volts.
|
| 3-74 |
Is this a trick?
Without modulation there is no envelope!
|
| 3-76 |
Here’s another one
just like on Slides 70-71. Same Ohms Law formula: P = E2 /
R.
Start with 500/2 so we
get Vp. Remember, we
can’t use Ohms Law on Vpp.
Multiply 250 x .707 and get 176.75.
Square t hat by multiplying it by itself.
You should have 31,240.56 right?
Divide that by 50 and you should get 624.81, which rounds
nicely to 625.
|
| 3-78 |
Just
like in slides 73 and 74, the PEP of an unmodulated carrier is
the same as the average power.
|
| 3-82 |
Refer to the next slide
for a 1 minute course in dB.
|
| 3-83 |
Don’t be overwhelmed by
all those numbers. You
only need to remember a few of them.
We’ll start by getting rid of the ones in parenthesis.
They are there to show you the actual value of 3 and 6 dB
when rounded.
Forget about the numbers
from 0 down to the bottom of the chart; they are the same as the
ones above the 0 except they are reciprocals.
What’s a reciprocal?
Simply what you get when you divide any number into 1.
Try it: 1 divided
by 1.995 (3 dB) is .5012 (-3 dB)
Now for the purpose of
this course, forget the far right column; we’re only going to be
using the P2/P1 column.
After you pass your test, come back here and memorize the V2/V1
column.
So what are we left
with? –1 db equals .7943 or nearly .8.
-3 dB equals .5012 or just about .5.
-6 equals .2512 or right at .25 and finally –10 equals .1
or 1/10th.
So what? Apply
these losses to 100 Watts of your precious transmitter output:
one dB loss equates to 20 Watts lost. 3 dB loss equates to 50
Watts lost or one half!
6 dB loss and you’ve given up three quarters of your power.
Finally, 10 dB loss and you have only 10 Watts left!
We'll explore this subject in more detail in the Feedlines
section; where dB really counts!
|
| 3-85 |
More on the subject of
dB. By definition, if
you apply 50 microvolts to the antenna terminal of a modern
receiver, and it’s input impedance is 50 Ohms (most are) then
your S-meter should read S-9.
Also by definition, one S-unit is 6 dB, so to increase
the S-meter reading from S-8 to S-9 you must increase the power
by 4.
|
| 3-87 |
You could go back
to the chart and you would see that 20 dB is 102
or 1 followed by 2 zeros.
You could also say that it’s 10 times stronger (10dB)
twice. Each time you do
the 10 dB calculation you add a zero.
|
| 3-95 |
What does linear mean?
If you plot the changes, and the result forms a straight
line, the plot is said to be linear.
If the line curves then the plot is said to be
non-linear. In
amplification, we don’t want anything to change except the
power. We want a linear
output so we use a linear amplifier.
If the amplifier produces a non-linear output, our signal
will be distorted.
|
| 3-101 |
Refer to Slide 3-50 for
a related question
|
| 3-103 |
By adding Negative
Feedback to the same amount of Positive Feedback, we cancel the
effects. Net sum zero
|
Module-3 continues Go back to top
| Slide Number |
Footnote |
| 3-105 |
Superheterodyne or simply Superhet:
The superheterodyne principle was originally conceived in
|
| 3-118 |
Images can be difficult
to handle. They can appear
on both sum and difference signals.
Read what Gordon West has to say about it on page 102 of the
Study Guide.
|
| 3-130 |
Very early designs used
direct conversion receivers for low cost and simplicity. Today,
several portable transceivers are available in kit form that use
direct conversion design.
|
| 3-148 |
See the notes on
“neutralization”
|
| 3-150 |
FET stands for
Field-Effect Transistor
|
| 3-154 |
Memory tip: Logic
circuits use two states: on-off, high-low, one-zero, they all
mean the same thing. In bipolar transistors, these state
correspond to saturation and cut-off.
|
| 3-177 | From the SARS Newsletter A short article describing digital logic circuits. |
| 3-181 |
From the handout: If
input A is “one” AND input B is “one” then output “Q”
should be “one”, but this is a NAND gate.
The little “NOT” thingy that attaches to the AND
gate makes it a NAND gate and reverses whatever the
answer would have been.
Contrary little devil!
|
| 3-183 |
From the handout:
Just like the previous example, if input A is “zero”
OR input B is “zero” then output “Q” should be “zero” but
this is a NOR gate which is an OR gate with a
NOT thingy attached to it.
Therefore, whatever the OR gate would have been,
the NOR is just the opposite.
|
| 3-185 |
From the handout. Basic digital circuits are binary because they deal with only two (bi) states: ON/OFF or HIGH/LOW or TRUE/FALSE. The terms all mean the same thing and are used interchangeably. Early computers actually used mechanical switches that were switched on or off, one at a time, to "program" the computer. It was found that a combination of 8 single pole switches could provide 256 different combinations which was sufficient to describe all the letters in the alphabet both upper and lower case, all numbers from 0 to 9, and several "special characters". We can answer all the Logic Circuit questions in the new pool with only 3 switches. Here's why: One switch, by itself yields only two states, TRUE or FALSE. It's either on or off. When you combine that with a second switch you now have 4 possible conditions: All FALSE or OFF, All TRUE or ON, Switch A TRUE, Switch B FALSE, and Switch A FALSE, Switch B TRUE. Combine these two switches with a third and you double that number of possibilities. Each new switch added doubles the number of possible states. |
| 3-191,193 | Abbreviation of complementary metal oxide semiconductor. Pronounced see-moss, CMOS is a widely used type of semiconductor. CMOS semiconductors use both NMOS (negative polarity) and PMOS (positive polarity) circuits. Since only one of the circuit types is on at any given time, CMOS chips require less power than chips using just one type of transistor. This makes them particularly attractive for use in battery-powered devices, such as portable computers. |
| End Notes for Module-3 |
Module-4 Go back to top
| Slide Number |
Footnote |
| 4-3 |
This illustration is
similar to one that can be found on page 116 of the Gordon West
Study Guide. There are
12 different formulas to help with Ohms Law and Power
calculations but only the 4 shown will be used in the Element-3
test. A description of
these 4 formulas is shown on the next slide.
|
| 4-4 |
Here are the 4 formulas
that are found in the Element-3 test.
|
| 4-6 |
Referring back to slide 4
we see that the only formula solving for E will work here.
Use E=SQR PR.
We first multiply P times
R or 1200 x 50 to get
60,000. Now simply press
your Square Root (SQR) key to get 244.94.
Round up to 245.
|
| 4-8 |
Referring to Slide
4 we see that P=E2 /
R will work for us.
First we “square” E by multiplying it by itself: 400 x 400 =
160,000. Now we divide
that by R (800) to get 200 Watts.
|
| 4-10 |
This one is “Easy as
PIE”. Multiply I times
E. 0.2 x 12 = 2.4 Watts.
Don’t forget the decimal point on the current (I).
|
| 4-12 |
This question uses
the fourth formula; P=I2 R
but be careful. These
formulas only work with whole units, that is Ohms, Volts, Amps,
Watts. When working with
fractional units such as milliamps and kilohms we must use
decimal points. Refer to
the next slide to see where the decimal points go.
7.0 milliamps is really
.007 Amps. Multiply .007
times itself and you get 0.000049 Amps. Now multiply that by
1250 Ohms (1.2 kilohms) and you
get 0.06125 Watts.
Can you convert that to Milliwatts?
The choices of the answers will do it for you: 0.06125
Watts is approximately 61 milliwatts.
|
| 4-14 |
There are three key
voltage measurements, RMS (Vrms), Peak (Vpk) and Peak to Peak (Vpp).
The Peak voltage is relative to ground.
RMS or Root Mean Square is more of an “average” voltage
over the duration of the AC cycle.
RMS voltage is calculated by multiplying 0.707 times the
peak voltage. The Peak
to Peak voltage measures from the peak of the positive swing to
the peak of the negative swing.
The 120 volt AC line
voltage in the wall is a peak value.
That means the RMS voltage is 85 volts and Peak
to Peak is 240 volts.
|
| 4-18 |
We talked about
reciprocals in Module-1.
A reciprocal is developed when you divide a number into 1.
We know that to find the RMS value of Vp you multiply it
by .707. But what if you
already have the RMS and you want to put it back?
You use the reciprocal of .707 (1 / .707) which is 1.414.
Try multiplying 120 Vrms by 1.414.
You should get 169.68 BUT WAIT!
Those tricky question pool guys.
The answer is not
B.169.7. Look at the
question again: They
want Vpp. You have to
double your answer: 169.68 x 2 = 339.36 ( round to 339.4)
|
| 4-20 |
What could be easier:
17 x .707 = 12.019.
Did you do this one in your head?
|
| 4-22 |
When they say “Linear”
power supply they are referring to the old fashion transformer
type.
|
| 4-24 |
Most components have an
equivalent series resistance (ESR).
This is composed of the various parts of the component
such as the leads and internal connections.
In some devices the ESR is not an issue but in switching
power supplies we want it to be as low as possible because it
affects the operation of the system.
|
| 4-34 |
Read the description and
see the graphics on pages 120 and 122 of the Gordon West Study
Guide.
|
| 4-52 |
High quality filter
capacitors can stay charged for days, even weeks.
If you are working around a high voltage power supply don’t
assume the bleeder resistors are doing their job.
Check for voltage before you touch anything.
|
| 4-54 |
Well, at least the
readout is more precise.
With an analog meter you need a mirrored dial to eliminate
parallax. That’s not a
requirement with a digital meter.
But they can be wrong also.
Buy a cheap-0 and it might be miles off!
|
| 4-56 |
With some things, just
getting close enough to measure can change it.
That’s one of the advantages of using an oscilloscope rather
than a meter.
|
| 4-82 |
Keyed connectors: Another
name for polarized connectors.
If you rely only on color, you will eventually hook it up
backwards. Trust me!
|
| 4-83 |
This is the schematic
that is handed out at the test session.
You will be asked to identify various components, for
example “G7A22 which symbol in figure G7-1 represents a variable
capacitor? Answer:
symbol 5. There are 6
questions pertaining to this handout, the most you can expect to
see on any test will be one of them.
(but which one?)
|
| 4-105 |
A special type of
resistor that we want to change when the temperature changes.
It is used primarily in thermostats, and weather
stations.
|
| 4-107 |
Refer to slide 97: In
calculating the value of components in series or parallel,
resistors and Inductors are treated alike, capacitors
just the opposite. Since
we are dealing with 3 identical components we can simply divide
3 into 10 to get the answer.
Bu what if they were not identical?
Convert each to it’s reciprocal, add them up, reconvert.
|
| 4-109 |
According to Kirchhoff's
second law, everything in a circuit must be accounted for.
You can’t end up with more or less than you started with.
|
| 4-110 |
This looks intimidating!
But they chose a value that makes it easy.
Go back to slide 105 and review. If three equal value
resistors in parallel produce 50 Ohms of resistance then the
resistors must be 150 Ohms each.
You need go no further, but test it if you wish: three
resistors of any value add up to the total of their values, in
this case 450 Ohms.
|
| 4-113 |
Now they’re making us do
a little work. Convert
each resistor to it’s reciprocal by dividing it into 1.
Now add up the three values and reconvert.
You should be adding: 0.1, 0.05, and 0.02 for a total of
0.17. Now divide 0.17
into 1 which will give you 5.88.
Round to 5.9
|
| 4-117 |
You can do this one in
your head. Referring to slide 97, capacitors in parallel are
treated numerically like resistors in series.
Just add ‘em up.
Don’t be intimidated by picofarads…this would be the same if it
was gigamegafarads. 5000
+ 5000 + 750 = 10750 whatevers.
|
| 4-119 |
This one is very much
like the resistor question in slide 110.
Capacitors in series are treated numerically like
resistors in parallel.
100 divided by 3 gives you 33.3 microfarads.
What if they were not of equal value?
Use the reciprocal trick like in slide 113.
You’ll have a chance to practice this very soon.
|
Module-4 continues Go back to top
| Slide Number |
Footnote |
| 4-121 |
Remember, Inductors are
treated numerically just like resistors.
In series, simply add the values.
|
| 4-123 |
Duck soup! Convert 20 to
it’s reciprocal by dividing it into 1.
You’ll get 0.05.
Do the same with 50, get 0.02.
Now add the two reciprocals and reconvert.
1 / 0.07 = 14.285 (round to 14.3)
|
| 4.130 |
Illustration of a
resonant circuit. Inductors and Capacitors both exhibit
Reactance or a resistance to AC measured in ohms.
Inductive reactance (Xl) increases with frequency and
capacitive reactance (Xc) decreases with frequency.
When inductors and capacitors are used in the same
circuit, the circuit is said to be resonant when inductive and
capacitive reactance are equal.
Matching load impedance
is important to insure maximum power delivery. Nice chart, but
relax. No questions pertain to this material.
|
| 4-138 |
You might think of it as
an audio tone. As the frequency increases, our ability to hear
it decreases due to the mass of our hearing apparatus.
|
| 4-140 |
Now we’re talking about
an inductor which behaves numerically just the opposite of a
capacitor.
|
| 4-148 |
There is a picture of a
wire wound resistor in the Gordon West Study Guide on page 136.
Notice that it’s nothing but a coil of wire.
Pure inductance!
|
| 4-154 |
The term “solenoid
inductor” is used to differentiate it from a toroidal inductor.
It is simply an inductor wound around a straight form.
Some contain a core material some don’t.
See a picture of a piece of “airdux” (pretty well beat
up) in the Gordon West Study Guide on page 135.
This is an example of a solenoid inductor.
|
| 4-158 |
Any time you have two or
more wires side by side you will have interstitial capacitance.
Coaxial cable for example has a specific capacitance
between the center conductor and the shield.
Telephone cable has a specific capacitance between the
conductors as well as between the conductors and the shield.
The capacitance is reduced greatly by separating the
conductors.
|
| 4-166 |
Most transformer
questions are simple ratio problems. For example, if the
transformer had the same number of turns in the primary as the
secondary, the ratio would be 1:1. This would be the design of
an isolating transformer.
What ever voltage is applied to the primary will appear
at the secondary. In
this example, the ratio is 4.5:1 (2250 / 500)
meaning that what ever voltage is applied to the primary,
4.5 times less will appear on the secondary winding.
Try it: 120 / 4.5
= 26.66 (round up).
|
| 4-168 |
This is also a ratio
problem but because we are invoking Ohms Law from the Power
side, square root gets involved.
First find the ratio by dividing the secondary impedance
into the primary impedance:
600 / 4 = 150.
Now find the square root of 150.
12.247 or 12.2:1
|
| End Module-4 |
Module-5 Go back to top
| Slide Number |
Footnote |
| 5-5 |
For a proper RF ground,
it’s important to use a heavy gauge copper (not aluminum) braid
or foil and keep the run length to a minimum.
Standard wire, even heavy gauge, or long runs can cause
your ground lead to act as an antenna and resonate.
A good ground will reduce RFI to other equipment,
minimize the risk of shock and reduce electrical interference.
At a minimum a ground rod should be 8 feet long.
This can be difficult to achieve in some locations and
multiple shorter rods tied together can be used.
|
| 5-25 |
Some examples:
Corroded gutters and downspouts,
Loose pole-line hardware (PG&E poles), antenna mast guy
wires not bonded.
|
| 5-33 |
Way back in Module-1 on
slide 15 we introduced a bogus phone number.
Have you memorized it? .707-468-1005.
468 is the number we use to calculate the length of a
half-wave antenna element.
468 / f(mHz). In
this example, 468 / 14.250 = 32.842 feet.
|
| 5-35 |
Another example using the
constant: 468. 468 /
3.55 = 131.83 feet.
|
| 5-39 |
You may already be aware
that many Hams use 50 Ohm coaxial cable to feed their antennas.
Most Hams think that a typical HF antenna has a
characteristic impedance of 50 Ohms.
Actually, a half-wave dipole’s characteristic impedance
is closer to 70 Ohms if you get it way up in the air.
If you install this antenna at the height most Hams do,
around 30 to 50 feet, it’s impedance will have dropped to around
50 Ohms. For this
reason, it is very difficult to adjust an HF antenna from a step
ladder.
|
| 5-41 |
You can match a high
impedance feedline such as twin lead or Ladderline to a dipole
by deliberately moving the feed point to one side.
If you get your 300 Ohm feedline attached at just the
right place you will have a nearly perfect match.
When using coaxial cable
(50 Ohms) you must be careful to get it exactly at the center of
the half-wave point.
Many Hams adjust the SWR of a new dipole by trimming the ends of
the wire. Shortening it up raises the resonant frequency, but
you must be careful to keep both sides exactly the same length.
If one is longer than the other, you have, in effect
attached the feed point off-center and you’ll never get your
match.
|
| 5-43 |
See the illustration on
the next slide. Imagine
you are looking down on the antenna from way up in the air. This
view is referred to as the E-plane.
|
| 5-44 |
Illustration of the radiation
pattern of a horizontal dipole.
If the dipole antenna was
the red line, the lobes above and below show the radiation
pattern at ½ wavelength above the ground.
This pattern actually rotates around the wire like a
donut. As the antenna is
lowered below ½ wavelength, the lobes flatten until it becomes
nearly omni directional.
|
| 5-46 |
Almost, but not quite.
Radiation off the ends of the wire will still be less
than that perpendicular to the wire.
|
| 5-47 |
Illustration of how the radiation
angle changes with height above ground.
Illustration of the
H-plane. Now we are
looking at the antenna off the end of the wire.
At ¼ wave, the radiation is as strong straight up as it
is in a horizontal direction.
As you raise the antenna even further, the upward
radiation diminishes and the power is added to the front to back
lobes as seen in the center diagram.
Notice that the maximum radiation in this diagram appears
to be about 45 degrees above the horizon.
Not bad for DX work.
The diagram on the right shows what happens when you
raise the antenna even further.
Additional lobes appear which will give you a DX
advantage, sort of like having a “broader paint brush”.
The lower lobe will maximize your distance.
Go back to Page 70 in the Gordon West Study Guide and
you’ll have a better understanding of “radiation angles”.
|
| 5-49 |
Sometimes this is exactly
what we want. If our goal is to work stations just beyond our
ground wave capability, we may do well with an NVIS antenna.
|
| 5-53 |
At heights below ¼ wave
you may have trouble matching it to your feedline.
If this is the case, use low loss coax and feed it with a
tuner.
|
| 5-57 |
Use the 468 constant
again, but don’t forget to divide the answer by 2.
468 gives you the length of a ½ wave antenna.
|
| 5-59 |
A typical vertical
antenna cut for the Ham bands will have a feed point impedance
of 35 Ohms more or less. By sloping the radials downward we can
raise the impedance to match the feedline.
|
| 5-64 |
This would seem to be at
odds with the previous question.
How are we to raise the feed point impedance to 50 Ohms
if our buried radials extend straight out from the base of the
antenna? A matching
network does the trick.
|
| 5-66 |
Makes sense. An omni
directional antenna receives signals and noise from every point
of the compass. A
directional antenna receives signals and noise from only a few
points on the compass.
(Of course you have to be able to rotate it.)
|
| 5-68 |
Here’s why: A resonant
antenna, properly matched to the feedline and transmitter
radiates nearly everything that is fed to it.
A random antenna, is not resonant anywhere (probably) and
if you feed it directly, much of the energy that would normally
be radiated is bounced back to the transmitter, often on the
outside of the feedline.
This can be a bad situation.
The reflected energy can flow all over your station
equipment including your microphone!
Pass the chap stick!
This is not to imply that
a random antenna is a bad thing. It can be quite useful
when properly installed and fed.
|
| 5-74 |
The driven element is
nothing more than a dipole.
The only difference, usually, is a dipole would be made
of wire and the driven element of a Yagi antenna is usually made
from tubing or rod material. The illustration on the next slide
shows this graphically.
|
| 5-75 |
Note the driven
element with the balun attached, the smaller directors, larger
reflector and the pattern with a large front lobe.
The driven element is approximately a half wave dipole.
As parasitic elements (directors and reflectors) are
added and the boom length is increased, the more gain is
provided by the antenna.
Reflectors are placed behind the driven element to reflect the
power forward and the directors act as conductors in front of
the wave. Reflectors are
generally ~3% longer than the driven element and directors ~3%
shorter. Five element
Yagis like this one yield 10-12dB gain over a dipole, based on
the design of the antenna.
Antenna designers have to
balance forward gain, front-to-back ratio, bandwidth and feed
point impedance when designing an antenna.
Some antennas will be optimized for maximum forward gain
to improve their output and others may have better front-to-back
ratios to improve their noise rejection.
Antenna bandwidth can be increased by using larger
diameter elements.
|
| 5-83 |
Take another look at the
radiation pattern on slide 75 to see a (distorted) picture of a
main lobe radiated from a directive antenna.
Regarding directivity, notice that the pattern is not
pointed the same direction as the antenna.
This is a drawing oversight.
In reality, the main lobe points the same direction as
the antenna’s boom.
|
| 5-87 |
Gain is like gas mileage.
It all depends on how far the manufacturer can stretch
the truth. “Theoretical”
is a great weasel-word.
|
| 5-91 |
A typical SWR Bandwidth
chart for 20 meters. The
arbitrary limit of 2.0 was set by the station operator based on
data provided by the equipment manufacturer.
SWR plots are made
at nine points between 14.000 and 14.100.
An acceptable bandwidth is shown between 14.025 and
14.060
|
| 5-94 |
In Gamma matching, the
shield of the driven element is attached to the driven element
in the normal manner but the center conductor, instead of being
attached to the element on the opposite side of the boom, is
attached some distance out from the boom to match the impedance.
A capacitor is inserted in the center conductor to tune
out the inductance of the extended center conductor. For a photo
of a gamma match on a UHF Yagi
see the article in the August 07 SARS newsletter
|
| 5-96 |
True enough, and that’s
the answer they’re looking for, but in reality insulation is
sometimes used to prevent bi-metallic contact of the various
antenna components. If
your antenna has insulation, that’s the main purpose.
|
Module-5 continues Go back to top
| Slide Number |
Footnote |
| 5-98 |
|