QEX_2005_11.pdf

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Forum for Communications Experimenters

November/ December 2005

Issue No. 233

KQ6F’s Direct-Conversion, Phasing-Method

SSB 100-W Transceiver for 40 and 75 Meters

ARRL

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Newington, CT USA 06111-1494

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QEX 11/2005

INCLUDING:

About the Cover

Rod (KQ6F) Brink’s 100 W

phasing SSB transceiver

begins on p 3.

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 offices.

POSTMASTER: Send address changes to:

QEX, 225 Main St, Newington, CT 06111-1494

Issue No 232

Harold Kramer, WJ1B

Publisher

Doug Smith, KF6DX

Editor

Robert Schetgen, KU7G

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

Technical Illustrator

Joe Shea

Production Assistant

Advertising Information Contact:

Janet L. Rocco, W1JLR

Business Services Manager

860-594-0203 direct

860-594-0200 ARRL

860-594-0303 fax

Circulation Department

Kathy Capodicasa, Circulation Manager

Cathy Stepina, QEX Circulation

Offices

225 Main St, Newington, CT 06111-1494 USA

Telephone: 860-594-0200

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

e-mail: qex@arrl.org

Subscription rate for 6 issues:

In the US: ARRL Member $24,

nonmember $36;

US by First Class Mail:

ARRL member $37, nonmember $49;

Elsewhere by Surface Mail (4-8 week delivery):

ARRL member $31, nonmember $43;

Canada by Airmail: ARRL member $40,

nonmember $52;

Elsewhere by Airmail: ARRL member $59,

nonmember $71.

Members are asked to include their membership

control number or a label from their QST when

applying.

Features

3 A Direct-Conversion Phasing-type SSB Rig

By Rod Brink, KQ6F

19 Quadrature Phase Concepts

By Gary Heckman, KC7FHP

24 A Single-Stage 1500 W Amplifier for 160/80/40 Meters

By Frank A. Carcia, WA1GFZ

29 Low-Noise-Sideband Differential Amplifier VFO

By Mal Crawford, K1MC

38 Reduced Bandwidth Voice Transmission

By Sam Cowan, WØOAJ

41 Source Coding and Digital Voice for PSK31

By Doug Smith, KF6DX

Columns

50 Antenna Options

By L. B. Cebik W4RNL

62 Upcoming Conferences

62 Next issue in QEX

57 2005 Index

59 Letters

Nov/Dec 2005 QEX Advertising Index

In order to ensure prompt delivery, we ask that

you periodically check the address information

on your mailing label. If you find any inaccura-

cies, please contact the Circulation Department

immediately. Thank you for your assistance.

American Radio Relay League: Cov II,

37, 64, Cov III, Cov IV

ARA West: 63

Atomic Time: 49

Down East Microwave, Inc.: 40

Elkins Marine Training International: 63

Expanded Spectrum Systems: 63

jwm Engineering: 56

National RF: 64

Nemal Electronics International, Inc.: 64

Noble Publishing Corp.: 64

RF Parts: 63

Teri Software: 40

Tucson Amateur Packet Radio Corp.: 18

Walter H. Volkmann: 28

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 office of the Publications

Manager ( permission@arrl.org )

Nov/Dec 2005 1

THE AMERICAN RADIO

RELAY LEAGUE

Empirical Outlook

The American Radio Relay League, Inc, is a

noncommercial association of radio amateurs,

organized for the promotion of interests in Amateur

Radio communication and experimentation, for

the establishment of networks to provide

communications in the event of disasters or other

emergencies, for the advancement of 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 organiza-

tion 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 two years by the general

membership. The officers are elected or

appointed by the Directors. The League is

noncommercial, and no one who could gain

financially 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 fide interest in Amateur Radio is the

only essential qualification 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 at 225 Main Street,

Newington, CT 06111 USA.

Emergency Preparedness and

the New Federalism

In light of the ongoing Hurricane

Katrina disaster, we offer a few words

that we hope will provoke your

thoughts and actions. This is not the

“blame game” that so many reprobates

have cited to deflect attention from

their irresponsibilities. It’s fact and

opinion.

It’s hard to imagine anyone who’s

not been touched in some way by the

current devastation. Did we know it

was coming? If so, what did we do

about it in advance? The first answer

is that we did know it was coming. The

second answer is that we didn’t do

nearly enough in advance. Those an-

swers should be self-evident.

Communications, command, control

and intelligence (C 3 I) are critical is-

sues during any emergency. Radio

amateurs are superb at providing com-

munications when all else fails. All we

have to do is arrive with the right

equipment where communications are

needed. We can benefit from improve-

ments in our planning and execution,

just as can those in command and con-

trol.

The ARRL Amateur Radio Emer-

gency Service Field Resources Manual

( ARES FRM ) and Public Service Com-

munications Manual PSCM ) are

finely crafted documents but nowhere

do they directly address the issue of

transporting hams to disaster areas.

Transportation is tacitly left to volun-

teers’ personal capabilities or to other

relief entities. The American Red

Cross and The Salvation Army can get

us where we need to be most of the time

but we have to get ourselves to places

like Montgomery, Alabama, first.

Our manuals refer to the Federal

Response Plan , now the US Depart-

ment of Homeland Security’s National

Response Plan , which was proudly an-

nounced in January 2005 by Tom

Ridge, then Secretary of the depart-

ment. The really odd thing is that this

plan doesn’t refer to Amateur Radio

anywhere in its 426 pages! In fairness,

we must state that ARRL is an affiliate

of the Citizen Corps, which is men-

tioned. Citizen Corps works through a

national network of state, local and

tribal Citizen Corps Councils that

bring together leaders from law

enforcement, fire, emergency medical

and other emergency management, vol-

unteer organizations, local elected offi-

cials, the private sector and other

community stakeholders. The League

also maintains memoranda of under-

standing with many governmental and

volunteer relief agencies. Those memo-

randa have helped us get our feet in the

door, as it were; but they don’t commit

the Federal Emergency Management

Agency (FEMA) or anyone else to pro-

vide us with transportation, food, shel-

ter, flashlights and so forth.

What can be done? Before we get to

that, check out a summary of the tech-

nical articles in this, our 233rd issue.

(Continued on p 62)

Telephone: 860-594-0200

In This Issue

At last we have Rod Brink, KQ6F’s

direct-conversion phasing rig. 75- and

40-meter ragchewers take note! Rod

documents his design of a good-sound-

ing rig, backing up his claims with mea-

surements. Gary Heckman, KC7FHP,

takes us on a related journey through

the theory behind quadrature phasing

concepts and unwanted sideband reduc-

tion. Frank Carcia, WA1GFZ, presents

a legal-limit power amplifier for those

bands and for 160 meters. It’s a solid-

state unit that uses inexpensive switch-

ing FETs in class C at 50 V dc.

Mal Crawford, K1MC, describes

his low-noise, differential-amplifier

VFO. The oscillator operates in the

5.3-5.5 MHz range, which makes it a

shoe-in for Heath and other popular

rigs.

Sam Cowan, WØOAJ, has some ideas

about reducing the bandwidth of

analog phone emissions. It’s a subject

that’s graced these pages before but

Sam’s take on it adds significant infor-

mation. Yours truly has a slightly dif-

ferent way of reducing voice bandwidth

that lends new meaning to the term,

“simultaneous voice and data.”

Contributing Editor L. B. Cebik,

W4RNL, offers the second part of his

look at antenna modeling software.

Read about the similarities, differ-

ences, limitations and options of what’s

out there.

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

Officers

President: JIM D. HAYNIE, W5JBP

3226 Newcastle Dr, Dallas, TX 75220-1640

Chief Executive Officer: DAVID SUMNER,

K1ZZ

The purpose of QEX is to:

1) provide a medium for the exchange of ideas

and information among Amateur Radio

experimenters,

2) document advanced technical work in the

Amateur Radio field, and

3) support efforts to advance the state of the

Amateur Radio art.

All correspondence concerning QEX should be

addressed 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

on IBM or Mac format 3.5-inch diskette in word-

processor format, if possible. We can redraw any

figures 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.

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.

Phasing-type SSB Rig

If carefully built and adjusted, a phasing-type SSB rig can sound

better than a superhet—in both transmit and receive. Here’s a

simple transceiver for ragchewing on 75 and 40 meters.

By Rod Brink, KQ6F

I n a recent ARRL publication, 1 Rick

was intrigued by his work and sur-

prised at its potential, thinking that

phasing rigs were permanently

“buried” decades ago by superhets

with crystal filters. Campbell’s work

seemed to indicate that while a phas-

ing transceiver might not have the

same selectivity as a multi-conversion

superhet with sharp filters, its minor

shortcomings are offset by other

advantages. These are: fewer adjust-

ments, fewer spurs, and in many cases,

better-sounding audio. This drew my

interest, as I am an enhanced-SSB-

audio fan. Inspired by his work, I set

about to develop a simple rig for

ragchewing on two of the low HF

bands, 75 and 40 meters. These were

chosen primarily because that’s where

I mostly hang out these days, since my

favorite 17-meter band has faded

nearly into oblivion with Cycle 23.

1 Notes appear on page 15.

25950 Paseo de Los Robles

Corral de Tierra, CA 93908

kq6f@redshift.com

Fig 1—Block diagram of an Opposite-Sideband Reject Mixer (OSRM). Signals above the LO frequency cancel at the output, while

signals below the LO frequency add to produce lower sideband. Mixer outputs to the low-pass filters may be reversed to produce upper

sideband.

Nov/Dec 2005 3

A Direct-Conversion

Campbell, KK7B, describes in

detail his experience working with

phasing-type transceiver circuits. I

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