Alinco DM-330MW review

A neat and sturdy power supply for the shack

The Alinco DM-330MW

Review

Switch-Mode Power Supply

n the past few months I’ve
discussed switch-mode power

I

supplies on a number of
occasions. Mostly, I’ve commented
on the the many domestic types that
seem to cause so much interference
with their switching harmonics on
the Amateur Bands. With this in mind
I thought it was time I looked at a
switch-mode supply that has been
designed for use in Amateur Radio
workshop or shack.

The unit I eventually chose for
reviewing was the Alinco DM-330MW
30A switch-mode unit. However, at
this stage I must admit to readers that
I have a great admiration for Alinco equipment as it
usually provides excellent value for money equipment
that’s also well finished and durable. I’m pleased to say
that after using the DM-330MW it ’s certainly up to the
standard I expect from Alinco.

Neat & Substantial

The photographs, Fig. 1 (the heading picture) and
Fig. 2 give a good impression of the neat and

substantial Alinco DM-330MW. It’s an attractive little

Fig. 2: The insides are well engineered from high quality components and

materials.

unit and is eminently practical looking with all the main
controls at the front with a clearly displayed voltage
and current supply indication via the built-in moving
coil meter. One of the coaxial shaft type controls
enables the user to vary (shift) the switching mode
frequency away from any incoming communications
signal. Quaintly, Alinco refer to it as the Noise Offset
Volume Contr ol and I’ll be referring to this again later
in the article.

When I opened the box after it had arrived overnight
from Nevada Radio in Portsmouth in Hampshire, I was
immediately impressed at the engineering involved
with the power supply. There’s a substantial ribbed
heat sink formed from cast aluminium alloy in a wrap­around type of casing. Indeed, the whole unit looked,
robust and attractive at the same time. Indeed, I’ll go
as far to say that it was beautifully finished.

Along with the main controls at the front, the power
supply has a good number of quick-connect sockets
(maximum 5A) at the front, along with the ubiquitous
cigar lighter (maximum 10A) type of socket. The main
– substantial – output terminals are at the rear, Fig.3,
along with the voltage pre-set adjustable control and
the separate ‘set’ switch.

The rear mounted mains input socket has the
necessary fast-blow type ceramic tube 4A fuse
mounted above it. The separate grounding post is
above the fuse socket.

The miniature cooling fan (it switches in
automatically as soon as the temperature reaches
45°C) is mounted on the left of the rear of the unit.
Although it’s only a small unit – as I was to find out
later – it’s extremely efficient.

Rob Mannion G3XFD takes a look at a switch-mode power supply that could prove
very useful in your shack.

18

Practical Wireless, February 2008

Instructions & Specifications

The folded leaflet that acts as the instruction manual is
simple, easy-to-understand and provides much of the
information that’s required. The only information that’s
missing in the leaflet is a circuit and a description of
how the unit works – switching frequency, etc., which
personally, I would like to know. The more we know
about our equipment the better we can use it!

The manufacturer’s specifications are straightforward:
The input voltage is 230V a.c. with the output voltage
variable between 5 and 15V d.c with less than 15mV
ripple peak-to-peak at the rated load. The output voltage
regulation is stated to be “less than 2%”, which I took
to mean that it varies less than 2%, and in fact, the
regulation (as measured by my test meter) as I operated
on the air, seemed better than Alinco claim.

The DM-330MW is rated at 30A maximum and 25A
continuous. The unit has built-in short circuit protection
(very quick acting indeed – as I proved on accidental
test!) and automatic current limiting at currents of over
30A.

On The Air

I decided to use the Alinco DM-330MW with my own
Alinco DX-70TH transceiver for the on the air tests using
c.w. and s.s.b. and spent a Saturday using both modes on

3.5, 7 and 14MHz. I also listened on 1.8MHz ‘Top Band’ for
r.f. noise comparison purposes (more on this later).

In use the DM-33MW was superbly efficient. Even
when I was operating at 100W on c.w. for long periods
the heat sink only became slightly warm
to touch. The fan pro
extremely quiet and
efficient it was very
difficult to detect
that it was on! In
fact, I had to turn
off the main rig (as
its own fan was
working quite hard)
to detect the sound
of the power supply
fan working.

Having had some
domestic switch-mode power supplies, I took some time
listening for harmonics from the switch-mode circuitry.
I hadn’t been able to detect many of the switching
harmonics with the supply on and with the rig’s antenna
disconnected – but I knew that the 1.8 and 3.5MHz bands
would be a real challenge!

However, listening on Top Band in the afternoon
until mid-evening I was very pleased to discover that
the received noise level using both the Alinco switch­mode power supply and my own 30A transformer bench
supply was basically the same. I really could not tell
the dif ference as I listened to my old friend Ian Keyser
G3ROO chasing the Top Band DX at RST599+10 on c.w.
from his QTH along the coast in Kent. In fact, listening on
Top Band was no problem at all, even though there were
some low level harmonics from the the DM-330MW as I
tuned over the band.

Up on 3.5MHz I was again delighted that the
difference in the general background noise between my

Product

transformer power supply
and the switch-mode unit
was barely detectable.
Tuning over the band I did,
as expected, encounter
some harmonics from the
switching circuitry but
none seemed troublesome.
Listening into several QSOs
I only encountered low level
harmonics and I was able to
tune these off the frequency
by using the Noise offset
volume control.

I had 20 or so c.w. QSOs
during the day on 3.5MHz
c.w. on various frequencies
although I didn’t have to use
the offset control once. It
was the same when I was
using s.s.b. up on the top
end of 80 metres – I again
didn’t have to use the off set
control.

Comparing Power
Supplies

However, when I plugged in
a 12V 4A switch-mode power
supply (from a miniature

ception of all Amateur

signals on all bands from 1.8 to 10MHz were
overwhelmed, although broadcast stations on 30 and 41
metres were of reasonable quality but accompanied by
various burbling noises!

The difference is what I expected between a correctly
filtered switch-mode supply in a metal casing to provide
screening and a plastic cased unit. It’s very unfortunate
that manufacturers of domestic type switch-mode
power supplies seemingly aren’t required to ensure
that harmonics from their units don’t cause problems
between 1.8 and 30MHz, whereas no doubt they place
more importance to attenuation on v.h.f. and u.h.f!

Altogether, I was very impressed by the Alinco
DM-330MW and I wouldn’t hesitate to recommend it to
readers. But on this occasion – as he summed up his
opinion on the unit so well – I’ll let Te x Swan G1T E X (who
came to collect the unit for photography) have the last
word.

Tex said that the DM-330MW, ‘’is quietly capable!’’ ●

The Alinco DM-330MW
30A switch-mode power
supply.

Company

eva

da Radio (UK Importers

N
and Distributors).

Contact

Sales at 023-9231-3090

Pros

Well made and easy-

o-

operate. Quiet and

t
efficient in operation and
well equipped with output
sockets.

Cons

None that the reviewer can

hi

nk of!

t

Price

£99.95 including free

er

y.

deliv

Supplier. My thanks for the

oa

n of the review unit go

l
to Nevada Radio, Unit 1,

Fitzherbert Spur, Farlington,
Portsmouth , Hampshire
PO6 1TT. Tel: [phone]­3090, Fax: [phone].
E-mail [e-mail]

ig. 3: The back of the unit has the

main output terminals as well as two

sser used controls.

ype TV), to power the

on receive only – the

were so many and so

Practical Wireless, February 2008

19