The W3EUT WHITE PAGES series...
The SWR Challenge...30 questions...you should know all the answers.
index for white pages...
These questions are
relative to your antenna system and might help you understand more
about that SWR reading you, without question, trust and believe.
I spend most of my
time reading technical books that relate to hundreds of subjects.
Many of them regarding electronics and radio, but I have also read
and studied several books on welding, mechanical design, auto body
repair, race engine building, high performance suspension and
chassis...and others related to sports like baseball and football. I
also enjoyed reading biographies written in first person. I rarely
read a book I did not like, but then I rarely read fiction.
I read a book for the third time just last week...yes for the
"third" time I read Reflections by M. W. Maxwell (W2DU). Mr. Maxwell
was an antenna genius. His biography is expressed in a few words as
a "technical marvel". He wrote an entire series for QST and the ARRL
that referenced for us , over decades, the properway to read
understand and deal with antenna design and in one case
"reflections". The book was based upon Walter's understanding and
teachings about the one subject that is most commonly
miss-interpreted subjects on our Ham Bands today.
Walter Maxwell as a Ham and like most of us "old farts" he did not
waste his knowledge on himself; as a technical advisor for the ARRL
he wrote several articles for QST and eventually for the Radio
Handbook and the Antenna Handbook. God Bless Walter Maxwell...his
lectures, white papers and magazine articles have become my personal
The following pages, including the questions here and the results
on the following pages, are all from Mr. Maxwells teachings. These
are not "opinions', but are fact that you can take to the bank.
Understand these principals and you will understand all that it
takes to enjoy your favorite hobby. I mean, if you follow carefully
and apply what you comprehend, your ability to "receive" and
"transmit" will be forever enhanced.
And now, 30 Questions, about SWR. You
should not fail these questions.
Anything less than perfect should
not be tolerated.
I was not motivated to do this paper after reading Walter
Maxwells book "Reflections ~ TRANSMISSION LINES AND ANTENNAS". While
I totally endorse Mr. Maxwell and give him 100% credit for this
questionnaire, I was not motivated by him, or his writings. I was
was however, motivated by individuals I have listened to on the HF
bands like 160, 75 and 40 meters. Some of the comments and
suggestions (actually they are lies) given to operators are not only
insane or misunderstood, many are down right dangerous. If you read
W2DU's articles, you will find out that not much information has
changed since Walter wrote his articles for QST, but what has
changed is the "level of testing" required to become an Amateur
Radio operator. Even if you "ace" the element IV testing, you will
probably miss most of these questions. These "true or false"
questions are general information that most of us "old farts" took
for granted. However somewhere in the past decade or so, these
"facts" have been forgotten or some how changed...
The "appliance operator" has taken all this for granted. To many of
these "memory rendered Hams", radio is not some technological
break-through like computers. Actually Radio and it's technology
lead to computers...but certainly not "Twitter" or "Face Book". Real
issue, you will not find this information posted on "You Tube"
videos, so it must be bogus...well if it is so bogus...then take the
Please understand that these questions relate to HF (1.5-30MHz)
frequencies and are common knowledge application to most "appliance"
based Ham Radio Stations.
Ok, put on that thinking cap...keep your
score the old fashioned way...write it down.
TRUE or FALSE:
(1) From an SWR reading, reflected power does not represent lost
power beyond cable attenuation [T] or [F]?
(2) Reflected power does not flow back into the transmitter or the
tuning device and it does not cause damage to the components there
in [T] or [F]?
(3) Any effort to lower an SWR of 2:1, on a coaxial line, is
completely wasted from the standpoint of significant increase in
power transfer [T] or [F]?
(4) An SWR reading of 1:1 is not proof of a good quality antenna
system or any indication that the system is radiating properly
[T] or [F]?
(5) Any antenna RADIATING element need not be self-resonant for full
"resonant" current flow, and the feed line need not be a particular
length, and termination point of radiator and feed line needs not a
"perfect match" [T] or [F]?
(6) If a suitable "matching network" (tuner) cancels all
reactance rendered in a non-resonant radiator, fed by a random
length feed-line that is mismatched to said radiator, the antenna
system resonant [T] or [F]?
(7) The majority of AM BROADCAST tower radiators operating between
540 KHz and 1600 KHz are at heights which mathematically are not
resonant at the frequency used [T] or [F]?
(8) The SWR on the transmission line between the
radiator and any matching device at the feed line input, is
determined by the mismatch at the "load" and cannot be "changed" by
the matching device [T] or [F]?
(9) Proper adjustment of a "matching device" for
maximum line current creates a "perfect mirror" of termination for
the reflected wave incident [T] or [F]?
(10) Total "return of reflection" of any amount of reflected
power from the radiator back to the input (caused by feed line
mismatch) is the reason such reflected power is not dissipated at
the transmitter [T] or [F]?
(11) A good antenna system including a well designed "matching
device" feeding an "open wire line" into a 130 foot center-fed
dipole at 50 feet does not radiate significantly more power
on 75 meters than does an 80 foot dipole at the same height fed with
the same power [T] or [F]?
(12) A self resonant dipole fed with RG-8 or RG-11 cut for 3750 KHz
does not, at that frequency, radiate more than it does at 3525 or
3985 KHz [T] or [F]?
(13) A 3750 KHz dipole fed with any length of 50 ohm coax and having
an SWR of 1:1 will yield an SWR of 6:1 at 3500 KHz and close to 5:1
at 4000 Khz thereby using the coax as a tuned feeder, with
no significant loss across the entire band [T] or [F]?
(14) With the use of a "transmatch" at the line input, proper
coupling between the transmitter and the tuned-coax feeder
(of any length) can be maintained over the entire 80 meter band
[T] or [F]?
(15) When using a DIPOLE antenna above ground,
changing the height above ground or lowering the ends of the DIPOLE
in order to increase or decrease radiator matching has an
insignificant effect on power absorption by the antenna. [T] or
Take a break now and look
over your answers...is there a pattern here? Most of the questions
relate to each other and one answer is the same or similar to
another preceding question...
(16) A 50 ohm tuned feed line at 3999 KHz can handle 700 watts of CW
power within SWR readings of 5:1. SSB input power at this frequency
can increase the ratings to up to 2000 watts. A 100 foot feed of RG8
with a 5:1 SWR has an attenuation loss of .78DB (or .46DB due to SWR)
which is meaningless in terms of a broadcast signal level. [T] or
(17) If the length of feed line is critical in order to obtain the
proper match, the identical matching impedance can be obtained
using any length of feed line by simply adding a "matching network"
[T] or [F]?
(18) High SWR in a coaxial feed line caused by
severe mis-match at the load, does not produce antenna currents on
the feed line and it does not cause the feed line to radiate [T]
(19) High SWR in a open wire feed line at HF
frequencies, caused by load mismatch does not produce currents nor
does it cause the feed line to radiate [T] or [F]?
(20) Both types of feed line may radiate, although
not significantly, caused by re-radiation of energy "coupled" into
the feed line from an asymmetrical positioning of said feed line to
the radiator [T] or [F]?
(21) SWR indicators need not be placed at the junction of the
feed line to the radiator in order to obtain a more accurate reading
[T] or [F]?
(22) The SWR in a feed line cannot be changed, adjusted or
controlled in any manner by varying the length of said feed line
[T] or [F]?
(23) If the SWR bridge indicator reading changes significantly when
moved a few feet along the feed line it indicates "antenna current"
is on the outside of the coax or the device is unreliable, or
both [T] or [F]?
(24) Any reactance added to a resonant load (purely resistive) in
order to compensate SWR readings will only make reflected matter
worse, not better [T] or [F]?
(25) Of all common known types of DIPOLE antennas,
including folded, fan, trap, coaxial or a combination of such, does
radiate more field (pattern) than another DIPOLE providing each has insignificant reactance losses while fed with the same power [T]
(26) RG8 coax used in a HF mobile installation
should have the MATCHING DEVICE located at the input to the coax in
order to improve operating bandwidth [T] or [F]?
(27) Center loaded mobile antennas of equal size having no input
matching device at the coax input, the best efficiency is obtained
on units with the LOWEST terminal resistance, not the lowest SWR
[T] or [F]?
(28) The RESONANT FREQUENCY of an antenna cannot be determined by
probing the input of the feed line using a grid-dip meter or noise
bridge, if that device cannot properly measure reactance [T] or
(29) Placing an SWR bridge at the input to the matching device
can offer the same results when placed at the output of the matching
device if the unit is read in reverse [T] or [F]?
(30) Tuning the receiver to the highest noise floor, using a
matching device yields the same result as tuning the transmitter to
the lowest SWR reading [T] or [F]?
There you have it. It is time for you to click here and get the
results. There is a page of information explaining just why the
answer is TRUE or FALSE. Be certain to have your eyes opened wide.
All too many of the so called "brain trust" will miss at least 5 of
these questions simply because they have been brain washed into
thinking like "appliance operators". You "no tuner freaks" you are
in for a serious awakening and the G5RV - Mystery - Bazooka gang,
well what have you to say about those compromise antennas now?
Go ahead look at your results
Thanks, The RFampGUY.
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