VHF UHF DX Book .pdf

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i

THE VHF/UHF DX BOOK
VOLUME 1
FIRST EDITION
Second Printing, with revisions

TYPESET & IMAGESET BY DIR PUBLISHING LTD
TEXT PRINTED BY THE BATH PRESS
Bath, Avon BA2 3BL
COVER PRINTED BY CLARK COLOUR
Long Marston, Hertfordshire HP23 4QR
IMAGE SETTING BY DIR PUBLISHING LTD
© 1995 DIR PUBLISHING LTD
All rights reserved. Apart from any fair dealing for the purpose of private study,
research, criticism or review, as permitted under the Copyright, Designs and Patents
Act 1988, no part of this publication may be reproduced, stored in a retrieval system
or transmitted in any form or by any means electronic, electrical, chemical, mechanical, optical, photocopying, recording or otherwise, without prior written permission.
All enquiries should be addressed to the Publisher.
DIR Publishing Ltd retains sole and exclusive right to produce, or to authorize others
to produce, printed-circuit boards or kits for the transverter designs published in this
book. Amateur constructors are authorized to build the equipment designs in this
book for their own use only.
Whilst every care has been taken in the production of this book, the Publishers
cannot be held legally responsible for accidental errors or consequences arising
therefrom.
ISBN  0 9520468 0 6

ii

EDITOR
Ian White G3SEK
AUTHORS
Roger Blackwell G4PMK
David Butler G4ASR
Geoff Grayer G3NAQ
Günter Hoch DL6WU
Sam Jewell G4DDK
John Nelson GW4FRX
Dave Powis G4HUP
Dave Robinson G4FRE/WG3I
Ian White G3SEK
John Wilkinson G4HGT

iii

2017 Digital Replica Edition
The VHF/UHF DX Book was written in the early to mid-1990s by a team of experienced
VHF/UHF DXers and equipment developers, in an effort to pass on our knowledge
and stimulate further developments.
Looking back, that plan worked very well... for a time. But as we entered the digital age,
information of lasting value became trapped on the printed pages and was lost
to the next generation of VHF/UHF DXers.
To keep that information alive, this digital replica of the Second Printing
dated 1995 has been released by kind permission of the copyright owner TRPublishing and its
proprietor Trevor Preece G3TRP.
As with all older books, the challenge for the reader is to separate the parts that are of lasting
value from other parts that have become dated. But we make no apology
for the latter; they remain an accurate snapshot of VHF/UHF DXing in its heyday.

Please do not try to duplicate the construction projects in this book
These designs are over 20 years old and many of the components
are no longer available.
More modern designs are available today, so seek them out and use those instead.

iv

CONTENTS
CHAPTER 1
Introduction
CHAPTER 2
VHF/UHF Propagation
CHAPTER 3
Operating
CHAPTER 4
Assembling your Station
CHAPTER 5
Receivers and Local Oscillators
CHAPTER 6
Transmitters, Power Amplifiers and EMC
CHAPTER 7
Beam Antennas and Feedlines
CHAPTER 8
144MHz
The Suffolk 144MHz Transverter
The W1SL 144MHz Power Amplifier
Antennas for 144MHz DX
CHAPTER 9
50MHz & 70MHz
A High-performance 50MHz Transverter
The Cray High-Performance 70MHz Transverter
Solid-State Power Amplifiers
Antennas for 50MHz and 70MHz
CHAPTER 10
432 MHz
A DXer’s Transverter for 432MHz
A Low-noise 432MHz GaAsFET Preamplifier
The K2RIW 432MHz Power Amplifier
Antennas for 432MHz DX
CHAPTER 11
Power Supplies and Control Units
CHAPTER 12
Test Equipment and Station Accessories

8-2
8-31
8-37

9-2
9-20
9-34
9-39

10-2
10-25
10-27
10-34

v

vi

CHAPTER 1
INTRODUCTION

1 – 1

INTRODUCTION

INTRODUCTION
by Ian White G3SEK

C

ontacting stations in far-away places
– ‘working DX’ – is one of amateur radio’s
greatest challenges, especially if you choose to
do it on the VHF and UHF bands.
When the VHF and UHF bands open up for
DX, they can produce some truly exotic
signals. If you start to get interested, you could
soon be hearing the throaty sound of signals
reflected back from an aurora, the stunning
strength of sporadic-E signals, the startling
meteor-bursts of SSB or high-speed Morse...
And one day – if you really go for it – you
could be hearing your own signals echoing
back from the moon.
If you are a newcomer who seldom works as
far as the next county, a 200-kilometre
contact is genuine DX. But if you’re keen you
will grow in confidence and competence until
you’re nonchalantly chatting with Continental stations every evening – and keeping a
keen lookout for “some real DX”!
Our expectations of the DX potential of the
VHF and UHF bands have increased vastly
over the past decade. These bands offer many
different modes of propagation, and activity
has increased so much that almost every DX
opening is recognised and exploited. From the
UK, amateurs have worked all over western
and central Europe on 144MHz and 432MHz –
but our horizons don’t end there. 50MHz can
cover the world at the height of the sunspot
cycle and moonbounce has brought the
Worked All Continents award within our
reach on the higher bands too.
The DX Century Club award on 50MHz –
100 countries confirmed – has already been
achieved by several UK stations in only a few

1 – 2

years, and even by US moonbouncer W5UN
on 144MHz. DXCC will surely be achieved on
other VHF/UHF bands within this book’s
lifetime.
It has become fashionable to claim that the
advent of ready-made black boxes signalled
the end of “real amateur radio”, and that radio
amateurs have been left behind by rapidly
advancing technology. The critics might be
right if we merely used our synthesized,
computer-controlled transceivers to make easy
contacts which the old-timers could have
managed with simple home-built equipment.
But they’re certainly wrong about VHF/UHF
DXers. We have used commercial equipment
and modern technology as a springboard to
do more than was ever possible before.
We are not making these vast strides by
copying professional practice. Radio amateurs
were among the first to appreciate the longdistance potential of the frequencies above
30MHz, and although we now share the VHF
and UHF spectrum with many terrestrial and
satellite services which span the world,
amateur radio still goes its own way. We
amateurs are the only people who use VHF
and UHF routinely for long-distance communication between skilled operators, so there
are no ready-made answers to our special
operating and technical requirements. We
have to work things out for ourselves.
VHF/UHF DX is one of the growing-points
where amateur radio shows that it still has a
real future – and that’s why we wrote this
book.

INTRODUCTION
CHASING THE DX
DXing is primarily an operating activity. The
objective is to get on the air and contact other
people, rather than building equipment for its
own sake – or just sitting and thinking about
it!
Chapter 2 is about Propagation, which is
at the heart of all DX-chasing. Unless you
understand the different ways by which VHF
and UHF signals can travel far beyond the
horizon, you run the risk of missing the best
DX. In amateur radio there are a lot of myths
and misconceptions about propagation so
Geoff Grayer G3NAQ has taken a fresh look at
the subject. Starting from basic physical
principles and using up-to-date scientific
information, he explains how the various
VHF/UHF DX propagation modes occur and
how to make the best use of them.
VHF/UHF DXers often use short-lived and
‘unreliable’ propagation modes such as
sporadic-E, aurora, meteor scatter and moonbounce. Many of these long-distance modes
are regarded by professional radio users as
merely an occasional nuisance to everyday
communication over shorter ranges, so they
still have not been fully explored. By exploiting these modes to work DX – and by doing it
as often as possible – amateurs can still
contribute to the development of radio
science.
Chapter 3 is about Operating – the actual
process of using your station. Even if you
could predict every single DX opening, you
won’t work much unless you’re also a good
operator. David Butler G4ASR explains that
operating technique is something which can
be developed and practised, just like any other
skill. You always need to match your operating to the needs of the moment, and the
propagation modes which produce only weak
or fleeting signals require some specialized
techniques, which Chapter 3 explains.
Many amateurs enjoy going on the air and
talking to people, happy to work whatever DX
comes their way. But some are not content
with that – they truly earn their reputation as
DX-chasers. Both types of people are DXers in
some degree and no firm line divides them.

Indeed, the same person may be a dedicated
DX-chaser on one band whilst remaining a
casual DXer on all the others.
Many DXers are working towards specific
goals in terms of contacts with particular
geographical locations. Contacting a large
number of different 2°x1° IARU Locator
‘squares’ is a very common long-term objective, especially for people who like an openended challenge. Others prefer objectives with
a definite end-point, eg contacting every UK
county. The more popular operating goals
earn certificates and awards, such as the RSGB
Squares and UK Counties awards and the
various awards for working more than 100
squares.
Contests are another popular operating
activity with VHF/UHF DXers, for a variety of
reasons. Some people view contests as an end
in themselves and on contest weekends they
set up large, well-equipped portable stations
on good sites and in rare locator squares.
Many home-station operators take the chance
to contact these big stations as an easy way of
working DX, while others are content just to
“give a few points away”. From the viewpoint
of this book, contests are a practical way of
measuring your own operating performance
and the DX potential of your station.

THE TECHNICAL CHALLENGES
The aim of this book is to bring together the
operating and the technical sides of VHF/UHF
DX. Each needs the other – a station assembled with no technical knowledge can never
be operated at full efficiency; and a technically
excellent station is sterile if it’s never used.
You don’t have to be put off by the word
“technical”. And you don’t need to worry if
you can’t understand everything in one gulp –
especially if you’re starting from scratch, or
fresh from the Radio Amateur’s Examination.
There’s no urgency. It may take years to
accumulate the practical experience to match
the theoretical knowledge you can gain from
books, and the two kinds of understanding
grow best together. If you want to work more
VHF/UHF DX, sooner or later you will naturally find yourself drawn into its technical and

1 – 3


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