QEX_2007_01_02.pdf

ARRL

225 Main Street

Newington, CT USA 06111-1494

The national association for

AMATEUR RADIO

Complies

with New

FCC Rules.

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This compact and lightweight 1kW desktop HF/50MHz linear power

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with the drive power of 85-90W. Bands set automatically with the built-in

band decoder . You can forget about the band setting when the amplifier

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Specifications

Frequency:

1.8 ~ 28MHz all amateur bands including WARC

bands and 50MHz

Mode:

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RF Drive:

85W typ. (100W max.)

Output Power:

HF 1kW PEP max., 930W CW (typ.)

50MHz 650W PEP max.

Matching Transceivers for Auto Band Decoder:

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Drain Voltage:

53V (when no RF drive)

Drain Current:

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Input Impedance:

50 OHM (unbalanced)

Output Impedance:

50 OHM (unbalanced)

Final Transistor:

SD2933 x 4 (MOS FET by ST micro)

Circuit:

Class AB parallel push-pull

Cooling Method:

Forced Air Cooling

MPU:

PIC 18F452 x 2

Multi-Meter:

Output Power – Pf 1Kw

Drain Voltage – Vd 60V

Drain Current – Id 50A

Input/Output Connectors:

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AC Power:

AC 230V (200/220/240V) – 10A max. (default)

AC 115V (100/110/124V) – 20A max.

AC Consumption:

1.9kVA max. when TX

Dimension:

10.7 x 5.6 x 14.3 inches (WxHxD)/272 x 142 x 363 mm

Weight:

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Accessories Included:

AC Power Cord

Band Decoder Cables included for Kenwood, ICOM and Yaesu

Spare Fuses and Plugs

User Manual

Optional Items:

Auto Antenna Tuner (HC-1.5KAT)

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Features

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overvoltage, band miss-set etc.

■ Built in power supply.

■ AC 230V (200/220/240V) default and AC 115V, (100/110/120V) (selectable).

■ Equipped with a control cable connection socket, for the HC-1.5KAT, auto

antenna tuner by Tokyo Hy-Power Labs.

■ Two antenna ports selectable from front panel.

■ Great for desktop or DXpedition!

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QEX (ISSN: 0886-8093) is published bimonthly

in January, March, May, July, September, and

November by the American Radio Relay League,

225 Main Street, Newington, CT 06111-1494.

Periodicals postage paid at Hartford, CT and at

additional mailing ofﬁ ces.

POSTMASTER: Send address changes to: QEX,

225 Main St, Newington, CT 06111-1494

Issue No 240

About the Cover

Mal Crawford, K1MC, describes his

“Ultimate Sidetone,” a single-tone,

keying-shaped sidetone circuit. Mal

added this circuit to Heath SB-301 and

SB-303 receivers to monitor his

CW sending. You can modify the

circuit values to suit other

receivers.

Harold Kramer, WJ1B

Publisher

Doug Smith, KF6DX

Editor

Larry Wolfgang, WR1B

Managing Editor

Lori Weinberg, KB1EIB

Assistant Editor

L. B. Cebik, W4RNL

Zack Lau, W1VT

Ray Mack, WD5IFS

Contributing Editors

Production Department

Steve Ford, WB8IMY

Publications Manager

Michelle Bloom, WB1ENT

Production Supervisor

Sue Fagan

Graphic Design Supervisor

Devon Neal, KB1NSR

Technical Illustrator

Joe Shea

Production Assistant

Advertising Information Contact:

Janet L. Rocco, W1JLR

Business Services

860-594-0203 direct

860-594-0200 ARRL

860-594-0303 fax

Circulation Department

Cathy Stepina, QEX Circulation

Ofﬁ ces

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Telephone: 860-594-0200

Fax: 860-594-0259 (24 hour direct line)

e-mail: qex@arrl.org

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Elsewhere by Airmail: ARRL member $59,

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Members are asked to include their membership

control number or a label from their QST when

applying.

Features

3 Octave for Transmission Lines

By Maynard Wright, W6PAP

9 An Alternative Transmission Line Equation

By Ron Barker, G4JNH, VK3INH

18 Observing Selective Fading in Real Time with

Dream Software

By John Stanley, K4ERO

23 In Search of New Receiver-Performance Paradigms, Part 2

By Doug Smith, KF6DX

31 The Ultimate Sidetone

By Mal Crawford, K1MC

37 All About the Discone Antenna: Antenna of Mysterious

Origin and Superb Broadband Performance

By Steve Stearns, K6OIK

45 A Large Aperture, Resonant, Regenerative Frame Antenna

(LARRFA)

By Bill Young, WD5HOH

47 On the Crossed-Field Antenna Performance, Part 1

Columns

55 Antenna Options

By L. B. Cebik, W4RNL

62 Letters

64 Next Issue in QEX

In order to ensure prompt delivery, we ask that

you periodically check the address information

on your mailing label. If you ﬁ nd any inaccura-

cies, please contact the Circulation Department

immediately. Thank you for your assistance.

Jan/Feb 2007 QEX Advertising Index

American Radio Relay League: 8, 17

ARA West: 64

Atomic Time: 36

Conformity Magazine: 22

Down East Microwave, Inc.: 64

Elkins Marine Training International: 64

Kenwood Communications: Cov III

National RF: 64

Nemal Electronics International, Inc.: 22

RF Parts: 17

Teri Software: 46

Timewave Technology, Inc: Cov IV, 30

Tokyo Hi-Power Labs, Inc.: Cov II

Tucson Amateur Packet Radio Corp.: 44

U.S. Dept. of State: 54

League Inc. For permission to quote or reprint

material from QEX or any ARRL publication,

send a written request including the issue date

(or book title), article, page numbers and a

description of where you intend to use the

reprinted material. Send the request to the

ofﬁ ce of the Publications Manager

( permission@arrl.org ).

Jan/Feb 2007 1

By Valentino Trainotti and Luis A. Dorado

THE AMERICAN RADIO

RELAY LEAGUE

Empirical Outlook

Doug Smith, KF6DX

kf6dx@arrl.org

The American Radio Relay League, Inc, is a

noncommercial association of radio amateurs,

organized for the promotion of interest in

Amateur Radio communication and experimenta-

tion, for the establishment of networks to provide

communications in the event of disasters or other

emergencies, for the advancement of the radio art

and of the public welfare, for the representation of

the radio amateur in legislative matters, and for

the maintenance of fraternalism and a high

standard of conduct.

ARRL is an incorporated association without

capital stock chartered under the laws of the state

of Connecticut, and is an exempt organization

under Section 501(c)(3) of the Internal Revenue

Code of 1986. Its affairs are governed by a Board

of Directors, whose voting members are elected

every three years by the general membership. The

ofﬁ cers are elected or appointed by the Directors.

The League is noncommercial, and no one who

could gain ﬁ nancially from the shaping of its

affairs is eligible for membership on its Board.

“Of, by, and for the radio amateur,” ARRL

numbers within its ranks the vast majority of active

amateurs in the nation and has a proud history of

achievement as the standard-bearer in amateur

affairs.

A bona ﬁ de interest in Amateur Radio is the only

essential qualiﬁ cation of membership; an Amateur

Radio license is not a prerequisite, although full

voting membership is granted only to licensed

amateurs in the US.

Membership inquiries and general corres-

pondence should be addressed to the

administrative headquarters:

Remote Possibilities

The grand legacy of Amateur Radio is

one of service and innovation. We can be

proud of our history but we can scarcely

afford to rest on our past accomplishments.

In that spirit, our leadership launched ma-

jor initiatives half a decade ago that are

now bearing fruit and that still point to the

future. Those initiatives — educational,

technical and political alike — embody a

good balance between what we commu-

nicate and how we communicate it. The

social aspects tend to get more coverage

than the technical, but we continually face

and exercise unique opportunities to har-

moniously combine them.

Four topics have been near the top of

our agenda: digital voice, high-speed

multimedia, software radio, and antenna

restrictions. Each by itself is experienc-

ing rapid and significant revolution.

Combined, they represent a solution that

doesn’t have to wait for a problem: re-

mote control.

We operators in antenna-restricted ar-

eas must ﬁ ght a good ﬁ ght on the legal

front but we have the technology to cir-

cumvent the issue. The cost of awesome

computing power in the form of personal

computers has come within reach of near-

ly every ham. Our access to high-quality

digital voice and image is now unprec-

edented, as largely driven by the cellu-

lar-phone and entertainment industries,

as well as the Internet. High-speed data

links are now routine, both over radio

and on land lines. Software radio is just

beginning to explore a realm of unlimited

possibilities.

Put it all together and you have a so-

lution to the antenna restriction problem

and a whole lot more. Transmitters and

receivers need not be colocated: They can

be placed at optimal locations. Remote

operation helps you avoid interfering

with your neighbors’ TVs, telephones

and radios. It may let you dodge inter-

ference (BPL!) on receive, too. It allows

clubs and individuals to pool their re-

sources to get better equipment. With the

proper gear, you can operate your remote

rig from just about any location on Earth.

Practical remote control of amateur rigs

is a reality that’s not getting enough trac-

tion.

We acknowledge that some knob-twist-

ers don’t like controlling their rigs with a

computer, but there’s no longer any rea-

son to sacriﬁ ce functionality for remote

control. To date, most of the practical sys-

tems we’ve seen are optimized for phone

operation and little else. What we need is

a universal system that supports not only

voice operation, but also CW and three

or four ancillary systems, such as an an-

tenna rotator, a RTTY or other modem, a

power ampliﬁ er and so on, perhaps using

EIA-232 serial ports. The system must in-

corporate positive feedback and telemetry

on the control link. It must comply with

the Section 97.213(b) rule about a three-

minute transmit limit should the control

link fail. Finally, and perhaps most impor-

tantly, it ought to be capable of operation

with any brand of transceiver having a

standard digital control port using exist-

ing manufacturers’ control software.

Except for certain software radios,

manufacturers have largely ignored the

call to publish application programming

interfaces (APIs) that would standardize

software control of their equipment and

make updates a cinch. We feel, therefore,

that what’s needed is software that effec-

tively extends all relevant PC functions,

such as two channels of audio, serial and

parallel ports between remote and con-

trol sites; and hardware for each site that

facilitates interface. It would be nice if

that system supported control links using

Internet Protocol (IP), dial-up serial mo-

dems and VHF or above radios, including

802.11 types.

Yes, all of that can be and is being

done now using a hodgepodge of off-the-

shelf hardware and software, but we owe

it to ourselves to get together and inte-

grate things in a universal way. It’s a neat

chance to bring together those individual

technologies that are proving so useful

elsewhere.

Note that the recent FCC Report and

Order in Docket 04-140, which went

into effect December 15, 2006, allows

auxiliary station operation (remote con-

trol links) on the 2-m band. Previously,

auxiliary operation was permitted over

links only on 1.25-m and shorter-wave-

length bands. The Commission speciﬁ cally

cited enhanced possibilities for remote

operation in its decision to modify Sec-

tion 97.201(b) of the rules.

What do you think? Write us.

ARRL, 225 Main Street, Newington, CT 06111 USA.

Telephone: 860-594-0200

FAX: 860-594-0259 (24-hour direct line)

Ofﬁ cers

President: JOEL HARRISON, W5ZN

528 Miller Rd, Judsonia, AR 72081

Chief Executive Ofﬁ cer: DAVID SUMNER, K1ZZ

The purpose of QEX is to:

1) provide a medium for the exchange of ideas

and information among Amateur Radio experiment-

ers,

2) document advanced technical work in the

Amateur Radio ﬁ eld, and

3) support efforts to advance the state of the

Amateur Radio art.

All correspondence concerning QEX should be ad-

dressed to the American Radio Relay League,

225 Main Street, Newington, CT 06111 USA.

Envelopes containing manuscripts and letters for

publication in QEX should be marked Editor, QEX.

Both theoretical and practical technical articles

are welcomed. Manuscripts should be submitted in

word-processor format, if possible. We can redraw

any ﬁ gures as long as their content is clear.

Photos should be glossy, color or black-and-white

prints of at least the size they are to appear in

QEX or high-resolution digital images (300 dots per

inch or higher at the printed size). Further

information for authors can be found on the Web at

www.arrl.org/qex/ or by e-mail to qex@arrl.org .

Any opinions expressed in QEX are those of

the authors, not necessarily those of the Editor or the

League. While we strive to ensure all material

is technically correct, authors are expected to

defend their own assertions. Products mentioned

are included for your information only; no

endorsement is implied. Readers are cautioned to

verify the availability of products before sending

money to vendors.

2 Jan/Feb 2007

Octave for Transmission

Lines

This installment in our series about the Octave program

looks at measuring feed line and antenna impedance.

Maynard Wright, W6PAP

wonderful thing. Various companies

are making impedance bridges for the

purpose. When combined with antenna design

and analysis software, an impedance bridge

can enable us to design and test antennas and

transmission lines much more rapidly and con-

veniently than has been the case in the past.

The point at which we would like to

measure impedances, though, is often out of

reach of our instruments. The center insula-

tor of a dipole 40 feet up is a difﬁ cult stretch

for most of us. We must therefore measure

antenna impedances through various lengths

of transmission line. The problem with

that is that the transmission line acts as an

impedance transformer and we really won’t

be measuring the impedance at the antenna

except in the case where the impedance is

exactly matched at the antenna.

Does that matter? If all we care about is

the match at the transmitter end of the line,

maybe not. We can usually match that point

pretty well, though, by using a tuner. The

principal reasons for measuring antenna

impedance is so that we can make sure that

the line is reasonably well matched to the

antenna to prevent a high SWR on the line

and to make sure that the antenna is going to

perform as we intended.

To refer a measurement at the near end

of a transmission line to the distant end, we

can use a Smith Chart as described on pages

21.4 and 21.5 of The 2007 ARRL Handbook . 1

The “Reﬂ ections on the Smith Chart” side-

bar from The ARRL Handbook is included

in this article for the reader’s convenience.

Alternatively, we can use Eq 11 on page 21.9

of the Handbook :

The Octave code in Table 1 implements

code for calculating the impedance at some

speciﬁ ed point along a transmission line. A

couple of housekeeping items are in order

before you examine the code. Lines preﬁ xed

with the character “#” are comment lines

and are ignored by Octave when a program

is executed. The same is true of portions of

a line of code beyond a “#” unless the “# is

included inside a quoted string such as in a

printf() statement. An ellipsis (“...”) at the end

of a line means that the next line is a continu-

ation of the line with the ellipsis.

Note that only a few lines of code actually

implement the equation we are interested in

solving. The rest provide for input from the

user and for formatted output of the results

much as was the case in the previous Octave

code we examined.

You might notice in Table 1 that there is

another version of the input impedance equa-

tion that is commented out with a leading

“#”. It’s much shorter than the one from the

Handbook and you can use it if you like as the

two expressions will yield identical answers.

The commented out code is a convenient form

(see Note 6, p 130), but it was not very useful

in past years because early implementations

of high-level languages like FORTRAN did

not include inverse hyperbolic functions. 7 In

addition, software implementations of inverse

functions such as arctanh() usually return the

principal value among many possibilities, and

Octave is no exception in this regard. In some

applications, this can lead to errors or uncer-

tain results, but it shouldn’t bother us here.

The code in Table 1 formats the input data

for use by the input impedance equation. The

equation wants the attenuation constant in

nepers per unit length, while it’s more con-

venient for us to input that characteristic of

the line in decibels per unit length. We make

() ()

=×

cosh

l l

sinh

cosh

(Eq 1)

where:

Z in = the input impedance of the line

Z L = the impedance seen at the terminating

end of the line

Z 0 = the characteristic impedance of the

line η = the complex loss coefﬁ cient of the

line (also known as the “complex propaga-

tion constant”)

A = the length of the line in the same units

as those used to deﬁ ne η

As the Handbook points out, this equation

is pretty tedious to apply by hand. Making

serious transmission-line calculations back

in the days of slide rules and trigonometry

tables involved many hours of work for a few

results. Today, we can ease the task using a

programmable calculator or a computer. In

fact, various folks have done that for us and

ARRL’s very capable TLA (Transmission Line

Analysis) program is included on the CD-

ROM that accompanies the 2007 Handbook .

There is some advantage to rolling our

own code, though. We can customize it as

we wish. If we want to input the distance in

furlongs, we can modify our code to handle

that. In addition, we can learn something

about the math involved in the problems we

are solving if we write our own code, even

if we make use of the software provided by

ARRL or others for day-to-day calculations.

The mathematical analysis tool Octave 2-5 al-

lows us to do this without needing to know

how to use a high-level language such as C .

1 Notes appear on page 8.

6930 Enright Dr

Citrus Heights, CA 95621-2837

w6pap@arrl.net

Jan/Feb 2007 3

T he ability to measure impedances is a

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