VINTAGE RADIO
By JOHN HILL
Valve portables
-
hard on batteries
Portable radio receivers date right back to the
early days of radio. Even then, the idea of being
able to listen to radio programs, no matter where
you went, had a certain amount of appeal. Portable
radio was also another avenue to be exploited in
order to sell wireless receivers.
Early portables, particularly
those from the late 1920s era, were
strictly for strong arm types only.
The word portable should have
been used with inverted commas
for these early receivers were only
marginally smaller than other
radios of the day.
A particular advertisement from
the late 1920s is a source of great
amusement to me if no-one else. The
advert shows J3. woman carrying a
huge "portable" radio but she is
shown only from the waist down.
Presumably, the reason for this is
not to reveal the pained expression
on her face due to the weight and
size of the receiver. Either that, or
they hired a muscle man for the
purpose of the photograph and
didn't wish to show him full length.
The possibility of getting a hernia
while lugging around an early portable was real; so too was the risk
of falling out of a tree whilst trying
to place an extension aerial in a
favourable place so that some form
of reception was possible. A frame
or loop aerial at ground level was
not the best way to pick up a signal
at some country picnic ground
situated miles from the big city stations. Most valve portables, even
late model ones, had some provision
for an external aerial.
But let's not be too critical. Every
new idea must have a starting point
somewhere - no matter how absurd it may seem to be some half
century or so later. It is marvellous
what 50 years of intense development can do!
Just how effective those very early portables were is just about
anyone's guess these days but some
of them must have worked well
enough to sustain interest in this
type of radio receiver. There have
always been portable radios and
they held a lot of appeal for those
who liked the outdoors. The thought
of being able to laze in the sun while
listening to the races or the cricket
inspired many to buy a portable
radio.
However, valve portables had a
few problems that made them
something of a disappointment to
many owners.
Expensive batteries
The big 8-inch speaker used in one particular Healing vaive portable dwarfs
the transistor radio shown in the foreground. The cabinet is of leatherette
covered timber.
12
SILICON CHIP
Although size and weight must
have been some disadvantage, the
expense of batteries was perhaps
the major drawback with valve
portables.
Unlike transistorised equipment,
a valve portable needs two power
supplies in the form of "A" and "B"
batteries. The "A" battery provides
the low tension supply for the valve
filaments, while the "B" battery or
batteries are used for a high tension supply.
"A" and "B" batteries have con-
A valve portable is powered from a 1.5V "A" battery (for the valve filaments)
and two 45V "B" batteries which provide the high tension supply. Compare
their size to the modern 9V transistor battery in the foreground.
aspect of their operation is a bit of
a humbug - particularly as the
batteries are no longer made.
There are two choices to make
with these old portables: you either
collect them or you don't collect
them. If you collect them you can
either just clean them up and
display them or get them going and
use them.
Using an old valve portable can
be a lot of fun. There are few things
that attract more attention than a
dirty great big old 1940s-style portable radio at a picnic or some
other outdoor function. It is not only
a great topic of conversation but it
can also lead to finding other old
radios. It always pays for collectors
to advertise their interest and having a working valve portable is one
way of doing it.
Providing power
This photo shows an old Hotpoint portable, together with its batteries. The
batteries took up a considerable amount of space inside the cabinet.
siderably different life spans and
one would expect to replace the
"A" battery at more regular intervals than the "B" battery. Buying a
full complement of batteries was a
costly experience. In fact, valve
portables were so expensive to run
they often had only a couple of sets
of batteries, after which the novelty
wore off and the set was put into a
cupboard and forgotten.
I base that last statement on the
fact that there are so many valve
portables about which still work
OK. The cost (in batteries) to wear
out a set of valves would have been
phenomenal and in many instances
valve portables were simply put
away because the average working
man really couldn't afford to run
one.
From a collector's point of view,
old portables generally don't hold
much interest unless one is enthusiastic enough to specialise in
them as an unusual aspect of valve
radio. Most collectors will give
them a miss because the battery
One major problem regarding
these old portables has already
been mentioned and that is the
unavailability of "A" and "B" batteries. Therefore, if one is to use
these obsolete portable radios,
suitable batteries must be improvised.
An "A" battery can be easily
made by wiring up half a dozen
standard "D" cells. Connecting
them together in parallel will produce a battery that will keep the
valve filaments glowing for quite
some time, especially if the set is used sparingly. The makeshift battery
can be wrapped in brown paper,
masking tape or placed inside a
suitable size cardboard box.
Likewise with the "B" battery. A
90 volt battery can be made up using 10 9V transistor batteries.
These must be connected together
in series and, as before, taped
together to keep them tidy and prevent short circuits.
If you are really keen, the improvised batteries could be disguised by placing them inside some
original battery boxes. The old batteries could be carefully removed
from their packaging and replaced
with new dry cells, thus dressing up
the replacement battery to look like
the real thing.
Incidentally, the average 4 or
5-valve portable consumes 8-10
milliamps of "B" battery current
SEPTEMBER 1989
13
Some receivers have a control knob
marked "economy" for this purpose
but lower battery consumption
means less performance and is
therefore only suitable for local station listening.
AC-DC sets
Most old valve portables were big and heavy, with no attempt made to
miniaturise components. This old valve portable used all standard size
components.
Not all valve portables were for
battery operation only; some were
of the AC-DC type. These more versatile portables were fitted with a
small power transformer, a rectifier valve and/or a metal oxide
rectifier to convert the AC voltage
from the mains to DC voltages.
Now many of these AC-DC sets
can be nasty things to play around
with for the simple reason that they
can have a live chassis when
operating on AC power. That means
that the chassis can have a 240 volt
AC potential and to touch such a
chassis under the wrong circumstances could be fatal. Speaking for myself, I consider that I am
much too young to die and I am sure
that you feel the same way.
·
So be careful when working on
an AC operated portable. They can
bite unexpectedly if you are unwary. It is wise to check out the
chassis potential with a multimeter
set to the AC volts scale. Test between chassis and earth. This simple check could well save your life.
The old & the new
This spiderweb wound aerial is cqnsiderably different to the ferrite types
used in modern-day portable transistor radios. The protruding wire is for an
external aerial connection.
which is about the same rate of
discharge that a 9V transistor battery would receive in normal service. So the improvised 90 volt battery will last a reasonable time and
is usable down to around 50-60
volts. Naturally, as the "B" battery
voltage drops, so does the performance of the set.
On the other hand, the "A" battery consumption on a valve portable is around 250-300 milliamps.
For this reason, the "A" batteries
require replacement at more frequent intervals.
14
SILICON CHIP
Today, as was the case 40 years
ago, batteries are expensive and it
will cost quite a few dollars to set
up any old valve portable to run
from battery power. Whether it is a
worthwhile exercise or not is entirely up to the individual.
Unlike a transistor radio, the
volume that a valve radio is
operated at has little or no effect on
battery consumption. The only way
battery life can be extended is to
place a small resistor in the filament circuit. This will reduce both
"A" and " B" battery consumption.
Comparing a valve portable with
a modern transistor radio is an interesting exercise for there are so
many incredible differences. Let's
take a quick look at some of the
more obvious ones.
The most noticeable difference is
size and weight. Almost no attempt
was made to make valve portables
small and most used stock standard
full size radio components. Only in
a few instances were there valve
portables made that could be
described as being small personal
portables.
Many of the portables from the
early post-war period had large
wooden ea binets that were covered
in leatherette. They still retained
the steel chassis type of construction that was typical of the valve
era. Although these sets were supposed to be portable, the only thing
that made them portable was the
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This metal-cased valve portable from Philips featured a sliding dial shutter
that also functioned as the on-off switch. The invention of the transistor made
valve portables completely obsolescent.
fact that they were cordless and
fitted with a carrying handle.
Miniaturisation never entered into
the equation in those days.
Some portables were built with
quality of sound in mind and a particular Healing model was actually
fitted with an 8-inch (20cm)
speaker. Now that's something
you're unlikely to see in a modern
tranny!
Philips made a range of pressed
steel portables that had quite a few
variations. Some were batteryoperated only, while others were
AC-DC models. Some models also
had a neon-like tuning indicator
which was probably pretty useless
anyway. Other models had a sliding
shutter that covered the dial when
the set was not in use. This cover
also activated the on/off switch and
the set automatically switched on
when the shutter was slid up to uncover the dial.
These Philips portable radios
also had a large loudspeaker,
although not quite in the same class
as the previously menti oned
Healing.
If anything has been truly
superseded it would have to be the
valve portable. The transistor made
it completely obsolete.
However, despite the fact that
these old portables are pretty
useless today, they represent the
best the radio industry could offer
prior to the solid state era. While
these old battery radios have a few
problems regarding suitable power
supplies, there is no reason why
they shouldn't take their place in
your vintage radio collection.
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SEPTEMBER1989
15
