Practical Wireless №9 2020.pdf

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SEPTEMBER 2020 THE
UK’S NUMBER ONE AMATEUR RADIO MAGAZINE SINCE 1932
NEW
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70 MHz Contest
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DEEP DOWN
How low frequencies are used
to communicate underground
TEST
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from MCR Communications
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automatic antenna switch
HOW TO
Constructing a
portable AM HF receiver
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Readers’ letters
Part two of our ‘how to’ series
You tell us what matters in your world
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Contents
5
Keylines
Don’s
main topic is choosing a rig that will maintain
your interest in the hobby.
September 2020 Vol. 96 No 9
On sale: 13 August 2020
Next issue on sale: 10 September 2020
ISSN 0141-0857
Practical Wireless
Warners Group Publications plc
The Maltings, West Street
Bourne, Lincs PE10 9PH
www.warnersgroup.co.uk
Tel 01778 391000
Editor
Don Field G3XTT
practicalwireless@warnersgroup.co.uk
Designer
Mike Edwards
mike.edwards@warnersgroup.co.uk
Advertisement Manager
Kristina Green
01778 392096
kristina.green@warnersgroup.co.uk
Production Manager
Nicola Lock
nicola.lock@warnersgroup.co.uk
Production Assistant
Charlotte Bamford
Charlotte.bamford@warnersgroup.co.uk
Marketing Manager
Katherine Brown
katherine.brown@warnersgroup.co.uk
Marketing Executive
Luke Hider
luke.hider@warnersgroup.co.uk
Publisher
Rob McDonnell
robm@warnersgroup.co.uk
Subscriptions
Subscriptions are available as little as £11.
Turn to our subscriptions page for full details.
Subscription Administration
Practical Wireless Subscriptions,
Warners Group Publications plc
The Maltings, West Street
Bourne, Lincs PE10 9PH
Tel: 01778 395 161
subscriptions@warnersgroup.co.uk
7
News
PW’s
monthly roundup of news from the UK and
internationally, including new products, club news
and recent events.
9
Radio Bookstore
Your one-stop shop for hobby-related titles, biogra-
phies, reference titles, historical accounts, technical
advice and successful building projects.
10
Review: The ‘MCR
Communications’ G5RV Antenna
Vince Lear G3TKN
takes a look at a commercially
made G5RV antenna.
14
How the RSGB is helping Radio
Amateurs to build their experience
Heather Parsons,
RSGB Communications Manager,
reports on recent developments to support new and
existing amateurs.
62
38
Carrying on the G3RJV way
Lee Aldridge G4EJB
revisits an MK484 TRF receiver
from
George’s
archives.
18
Icom Automatic Antenna Switch
Peter Edwards GW8ARR describes an automatic
antenna switch for an IC-7300 but which can be
modified to work with other transceivers too.
42
Valve & Vintage
Tony Smith G4FAI
tells the tale of a little-known
period of domestic receiver design and manufacture.
22
Data Modes
Mike Richards G4WNC
goes back to basics, with a
‘from the ground-up’ explanation of data modes.
46
HF Highlights
Steve Telenius-Lowe PJ4DX
reports on a recent pub-
lication that foretells a great sunspot cycle to come!
26
World of VHF
Tim Kirby G4VXE
reflects on making duplicate QSOs
and has more exciting news about D4VHF.
50
Book Review: Portishead Radio
Don G3XTT
takes a look at a recently-published book
about the maritime radio service and, in particular,
Portishead Radio.
Components for PW projects
In general, all components used in constructing
PW
projects are available from a variety of
component suppliers. Where special, or difficult
to obtain, components are specified a supplier will
be quoted in the article.
Photocopies & Back Issues
We can supply back issues, but we only keep
them for one year. If you are looking for an article
or review that you missed first time around, we
can still help. If we don’t have the actual issue
we can always supply a photocopy or PDF file of
the article.
Technical Help
We regret that due to Editorial timescales, replies
to technical queries cannot be given over the
telephone. Any technical queries are unlikely to
receive immediate attention so, if you require
help with problems relating to topics covered in
PW, please either contact the author of the article
directly or write or send an email to the Editor and
we’ll do our best to reply as soon as we can.
32
What Next
Colin Redwood G6MXL
continues his advice on the
best way to start out in the hobby.
52
Making Waves
Steve White G3ZVW
takes a look at a form of radio
communication that’s going on around us all the time
but which very few people think about, even though it
is very important – RADAR.
54
Doing it by Design
Eric Edwards GW8LJJ
describes a portable receiver
for AM reception on 80 through 60m.
56
The Twelfth Practical Wireless
70MHz Contest
Colin Redwood G6MXL
invites readers to participate
in the
Practical Wireless
70MHz Contest.
58
Notes from a Small Station
10
Joe Chester M1MWD
ponders the vagaries of propa-
gation and the effects of rain.
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4
PRACTICAL WIRELESS
September 2020
Keylines
I
t seems that we are gradually re-
turning to something approach-
ing normality (the new normal?)
but on the radio front all is still far
from normal, with most events cancelled
(the Newark Hamfest being the latest
and, in UK terms, the highest profile),
DXpeditions pretty much non-existent
and portable operations in contests such
as the recent IOTA event positively disal-
lowed. The good news is, though, that our
hobby remains in good shape. Indeed,
remarkably so, with a continuing influx of
new and returning amateurs, many clubs
managing to keep going through Zoom
and similar get-togethers and, of course,
person-to-person communication able to
continue in a suitably socially-distanced
way over the airwaves.
26
60
S-Meter versus Time Display for
the 21st Century
Ian Dilworth G3WRT
makes the case for an alterna-
tive approach to an S-meter, one for the 21st century?
Getting Started
In this month’s
What Next
column,
Colin
Redwood G6MXL
gives more tips about
getting started in the hobby. In par-
ticular, he recommends buying an HF
radio in order to have access to inter-
national communication. There is an
interesting trade-off here in terms of
outlay and satisfaction. I recently in-
vested in a couple of VHF/UHF hand-
helds, partly out of curiosity and partly
because they will be handy from time to
time, such as at rallies and, indeed, for
communicating with fellow team mem-
bers on our DXpeditions (if I ever get to
travel again!).
The first is a Baofeng UV-9R, cheap
as chips at £39.98 and with a torch and
alarm included. The second is a Yaesu
FT-4XE, which set me back £70.90 in-
cluding postage. Both sets were consid-
erably cheaper than the second-hand
Yaesu VX-5 (admittedly a tri-band rig)
that I bought from Lowes in Plymouth
(that dates me!) more years ago than I
care to remember. The Baofeng is far
less user friendly than the Yaesu, re-
quiring each channel (or channel pair in
the case of repeaters) to be set up and
stored, whereas the Yaesu knows about
repeater frequencies and shifts from the
outset. Presumably this is because the
Baofeng is also sold (albeit in a slightly
different version) in huge numbers for
commercial and other purposes (which
will also be how they can manufacture
and sell them so cheaply).
62
Radio at Depth (Part I)
Mike Bedford G4AEE
investigates how low frequen-
cies can be used to communicate with cavers
underground, and how amateurs have contributed to
this fascinating application of radio technology.
68
Readers’ Letters
Topics this month include Tiger Radio, returning to
the hobby and more on whether transistors wear out.
But neither rig will be of much use un-
less there is someone to talk to and even
here, in sight of the Mendip repeater,
with its widespread coverage, includ-
ing the Bristol area, there is little enough
activity. I have worked folk via the re-
peater, but they are few and far between
(compared with years ago when I would
guess it was in constant use).
I’m not entirely sure why this should
be, particularly during lockdown, when I
would have thought folk would want to
talk to locals and share experiences. It
may in part be that nowadays there are
so many facets to the hobby that other
aspects beckon. Digital voice modes on
VHF and UHF permit global communi-
cation but the entry price is, of course,
very much higher. As, indeed, is the price
of getting started on HF although it is
certainly possible to buy a very compe-
tent HF rig second-hand for under £500,
which, while it may sound a lot, is prob-
ably no more than people would happily
spend on other hobbies.
But even on HF there is often a dearth
of activity (except during contests), so
where is everyone? I would hate to think
of them passing the licence exams and
quickly losing interest. So, we should
certainly commend the RSGB Beyond
Exams initiative, which we have some in-
formation about in this issue. The snag,
it seems to me, is that it requires local
clubs to take up the baton and I suspect
that many clubs will lack the resources
or the will to do so. Only time will tell.
52
Don Field
Editor,
Practical Wireless Magazine
Read more radio news and reviews at www.radioenthusiast.co.uk/news
September 2020
PRACTICAL WIRELESS
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