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Vintage Radio
By RODNEY CHAMPNESS, VK3UG
The batteries used to
power vintage radios
This view shows an
assortment of old Eveready
1.5V cells and batteries,
together with a 3V battery
at far right. A Burgess 4.5V
battery is also shown.
Many valve radios were battery-powered
but a lot of the battery types used are now
obsolete and no longer available. However,
with a little ingenuity, sets that would
otherwise be static displays only can be
restored to full working order.
W
HEN WE STOP to think about
it, our civilisation would almost
grind to a halt without batteries. Without them, there would be no iPods, no
mobile phones, no handheld remote
controls, no torches, no hearing aids,
no battery-powered radios, no cordless
mice or keyboards and no cordless
telephones, to name just some of the
equipment we now take for granted.
Even worse, we would have to handcrank our cars to start them if we didn’t
84 Silicon Chip
have batteries to do the job for us!
Batteries were used to power many
early valve radio receivers, particularly in areas where mains power was
unavailable. These batteries consisted
of both primary (non-rechargeable)
and secondary (rechargeable) types. A
primary battery is one that uses up its
chemicals in an irreversible reaction
and is disposed of after use (ie, after it
has gone “flat”). By contrast, secondary batteries can be recharged because
the chemical reactions that take place
inside them are reversible.
Primary cells
Many types of primary cells had
been developed by the early 20th
century. These included the Fuller
bichromate cell, Edison cell, Grenet
Bichromate cell, Bunsen cell, Daniell
cell, Gravity cell, Daniell gravity cell,
Grove cell, Poggendorff cell, silver
chloride cell, air depolarised cells
and last but not least, Leclanche cells.
Many of these cells were a variation
on a theme and all were an attempt to
provide electrical energy in an economical and convenient way.
Because quite corrosive chemical
solutions were used in many of these
cells, considerable care was necessary
when handling them. In fact, none of
these cells were convenient to use in
radios in their original format. However, the Leclanche cell was eventually
modified to give us the now familiar
“dry cell”. This is now the most common primary cell used in portable
radios.
Typically, a Leclanche dry cell has a
positive carbon pole contained in a porous container filled with manganese
dioxide which acts as a depolariser
(the depolariser is used to remove the
hydrogen gas that is developed on the
carbon pole). This assembly stands in a
container of ammonium chloride paste
which also includes a negative zinc
pole. It produces an output voltage of
nominally 1.5V.
One of the accompanying photos
shows three glass-encased cells. The
front one is an early Leclanche cell.
However, we are more familiar with
the normal torch cell in the same photograph, which is basically a refined
version of the Leclanche cell and is
much easier to use.
Secondary cells
By contrast with primary cells,
secondary cells are a more recent
development which occurred around
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Dry batteries designed to power valve radio sets came in all
shapes and sizes. The units shown here are now all obsolete.
1800. However, practical cells did not
become available until about 1880.
As stated above, secondary cells are
rechargeable and include lead-acid
car batteries and the nickel-cadmium
(nicad) and nickel-metal hydride
(NiMH) cells now used in many
electronic devices. Because they are
rechargeable, they can significantly
reduce long-term battery costs in many
applications. Early secondary cells
include Plante cells, Faure cells and
alkaline cells, with quite a few variations on a theme.
During the early 20th century, secondary cells were classified according to their construction as follows:
lead sulphuric acid cells, lead-zinc
cells, lead-copper cells and alkaline
zincate cells. The lead-acid cell is
now the main secondary cell used in
the automotive industry, while NiFe
cells (nickel and iron electrodes) and,
more recently, nickel cadmium cells
are the main alkaline-based electrolyte
secondary cells commonly in use.
Maintenance
Rather than being discarded, early
primary cells were refurbished. The
elements that were used up in the
chemical reactions were replaced,
after which the cell was again ready
for use. However, this was a messy
and quite often expensive exercise.
Furthermore, the chemicals could be
quite corrosive, so care was essential.
siliconchip.com.au
Almost without exception, primary
cells now are thrown away when they
become exhausted. Chinese “D” cells
may cost from 25 cents upwards while
high-quality alkaline cells may cost in
the region of $2.00 each but will give
superior service.
It’s also interesting to note that
some attempts were made to recharge
primary cells back in the 1950s and
early 1960s. During that era, a number of portable radio manufacturers
installed a “re-activation” circuit into
their radios. When the portable was
connected to the mains, the set would
work directly off the mains and the
supply circuitry would also be used
to “recharge” the installed dry
batteries.
In practice, various protocols had to be followed to
recharge the batteries and the
number of recharges the batteries could successfully take was
decidedly vague. Usually, the
instructions were not to use the
batteries in the set to the point
of being completely discharged
before plugging the set into the
mains again. Even four to five
semi-successful “recharges” was
considered good value, as the batteries
were quite expensive.
HMV recommended that the batteries in their sets be “re-activated” for
six hours for every hour of operation.
They believed that a set was typically
used for around two hours a day, so
an overnight charge would be the most
convenient way of doing this.
However, HMV also inferred that the
batteries must be reactivated as soon as
possible after any discharge, otherwise
recharging would not be successful.
Apparently, using the batteries on
successive days without reactivation
would make later attempts futile.
I have no idea as to whether this idea
would work with today’s dry cells,
including alkaline types. However,
High-discharge testers like this
unit were used for checking
lead-acid cells. The battery is
shown for size comparison.
March 2008 85
Another handy test tool was the
hydrometer, used to test the specific
gravity of the electrolyte in leadacid cells.
An assortment of transistor radio batteries. These are mainly 9V types, the
main exception being the 2510 at right which had 2 x 7.5V outputs.
the instructions on many of these
batteries indicate that it should not
be attempted. Perhaps this is because
people may endeavour to recharge the
cells at too high a rate which could
cause them to explode. You have been
warned!
During in the 1960s and 1970s,
Astor and AWA also made some
portable-cum-car radio transistorised
receivers that used rechargeable nicad
AA cells. These sets were rather advanced for their time and they were
fairly expensive.
Secondary cell problems
A disadvantage of early lead-acid
secondary batteries was that it was
necessary to keep an eye on the
charging procedure. This involved
using hydrometer to check the charge
condition of each unsealed lead-acid
cell. A high-discharge cell tester was
also commonly used with car batteries.
During this procedure, it was very
important not to smoke or create any
sparks. This was to prevent the hydrogen gas given off during charging
from exploding. It’s a warning that’s
still valid today.
Early valve radios
Early valve radios commonly used
the 201 or the later 201A triode valves.
These required filament voltages of 5A
at 1A and 5V at 0.25A respectively.
In practice, these valves were
commonly run from a 6V lead-acid
battery with a rheostat in series with
the filaments to reduce the applied
voltage to 5V.
By contrast, the high-tension (HT)
voltage for the 201 & 201A varied
from around 22.5V to about 135V,
depending on the valve’s function in
the circuit. The HT current drain was
usually less than 25mA for the entire
receiver.
In the early days, miniature leadacid batteries were sometimes made
up to supply the HT requirements of
such receivers. Just imagine a bank of
60 cells supplying 120V to a receiver,
then imagine having to check the electrolyte in each of these cells each time
they had to be charged! That would
really have been fun!
I have only ever seen one example of
these miniature batteries so I suspect
that they weren’t all that popular.
An alternative involved using a bank
of dry cells to provide the necessary
HT voltage and current for the receiver.
For a 135V HT rail, this involved connecting 90 cells in series.
It’s worth noting here that dry cell
manufacturers standardised on the
size of the cells used in their batteries
at an early stage. For the HT batteries, they used A-size cells which are
smaller than C-size cells. We don’t
see them around these days but one
is shown in the lead photo, standing
alongside the cyclindrical No.6 cell.
Dry cell deficiencies
Eveready made a wide range of dry batteries for valve radios, the larger “B”
units shown here delivering 45V. Diamond also made a range of dry batteries.
86 Silicon Chip
Unfortunately, early dry cells did
have some deficiencies. First, the insulation used between the cells in a
battery was commonly cardboard and
in a moist environment this became
slightly conductive. As a result, the
batteries would discharge and go flat
over a period of several months, a
problem that was particularly evident
in hot, humid areas.
In addition, some early dry cells had
a “breather” vent and the moisture in
the paste-type electrolyte evaporated
over a period of several months. As
a result, early dry cells had a rather
limited shelf life.
The earliest Traeger pedal radios (for
the Flying Doctor Service) were commonly used in tropical areas and in an
endeavour to overcome the discharge
siliconchip.com.au
A Clyde 2V lead-acid cell (circa
1930s-40s) is shown here, together
with a Leclanche cell at the front
and two Edison cells at right.
problems in dry cells, only 9V of HT
was used from two 4.5V batteries.
The Australian army also initially
had problems with dry batteries in
their transceivers in the tropics during WWII. However, they were able
to reduce the problems by completely
sealing the batteries in wax. Of course,
cost was not of prime concern in that
instance.
Dry batteries have changed enormously over the years and today’s
batteries are considerably better than
those used during the early valve
radio era. In particular, the layer type
method of construction was a major
advance in packaging and was coupled
with good insulation techniques and
economy of manufacture. The subminiature overseas-made HT batteries,
the Australian 490P & 482 types and
transistor receiver batteries such as
the 2761, 2362, 2510, 2364, 216 and
286, etc, all used this very efficient
construction method.
When Australian manufacture of
transistor radios ceased, most of the
“specials” for the Australian receivers quickly became hard to get and
in some cases disappeared from the
market. The 276P “evolved” and became a lower grade battery. The layer
construction was dispensed with and
six “C” cells in a holder were incorporated in its place. This was a backward
step, as the contacts in the holder
didn’t always make good contact and
the electrical capacity of the battery
was reduced.
By contrast, large low-voltage dry
batteries did not depart from the original concept of wiring multiple A, C, D,
E & F cells in parallel (I’ve never found
any reference to a “B” cell). An advantage here was that insulation was not
a problem with such low voltages. We
are all familiar with the “C” and “D”
cell sizes and the “A” was basically a
little brother to the “C” cell. Batteries
such as the X250 and 745 1.5V types
used the “F” cell.
Towards the end of the valve era,
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A collection of
Stanmor dry
batteries. There
was nothing
fancy about the
packaging used
for these units.
portable receivers often used a combined low-tension (LT) and HT battery
in the one case. Apparently, the HT
sections were of layer construction
while the LT sections were built using
“D”, “E” or “F” cells.
One such battery was the 759 which
supplied 1.5V and 90V. This was
suitable for household sets but was
too big for portables. Another battery
pack for use in rural areas was made
by Eveready and contained one X250
1.5V battery and two 470 22.5/45V
batteries. Although they were not all in
the same case, they were all supplied
together in the same delivery carton.
Of course, using an “all in one”
meant that if one section failed, the
whole battery had to be replaced.
Lead-acid batteries were predomin
antly used for supplying valve heaters
and for powering vibrator HT power
supplies. In practice, 2V cells varied
from 25Ah capacity to 130Ah, while
6V batteries varied between 60Ah
and 160Ah in capacity. In 1937, these
March 2008 87
Diamond made a large variety of dry batteries for valve radios, including
45V “B” batteries and 4.5V and 1.5V “A” batteries.
varied in cost from about 17/6 ($1.75)
to about £5/11/6 ($11.15). At that time
the average weekly wage was about
£4/10/- ($9.00), so they were quite
expensive.
The use of 2V lead-acid cells
declined quite rapidly when 1.4V
filament valves were introduced,
replacing those with 2V filaments.
However, 6V (and occasionally 4V)
lead-acid batteries remained in use
with vibrator-powered receivers until
around the mid 1950s.
Battery life
Most radio batteries were rated for
a 20-hour discharge rate. In practice,
a typical 5-valve receiver using 2V
valves draws 720mA. This meant
that a fully-charged 25Ah cell would
need recharging after about 35 hours,
whereas a 130Ah cell would operate
for about 180 hours.
Similarly, vibrator-powered radios
with efficient power supplies typically
drew around 1A from a 6V battery.
That makes the maths simple – a 60Ah
battery would last around 60 hours
and a 160Ah battery would last around
160 hours.
As with lead-acid batteries, dry battery life depends on the battery capac-
ity, the current drawn and the amount
of time that current is drawn during
each listening session. In practice,
the battery life in transistor receivers
varies from around 30 hours for a 9V
216 battery to about 300 hours for a
276P battery and up to 1000 hours for
a 286 (as quoted by Kriesler for one of
their sets).
In typical valve portable receivers,
the life of a 1.5V 745 battery allied with
a pair of 45V 482 batteries was usually
somewhere around 300 hours. The
Australian “miniature” portables used
two 950 cells to provide the filament
current and a 467 67.5V battery to supply the HT current. In operation, the
two 950 cells would last around 30-40
hours, while the 467 HT battery would
probably last up to twice as long.
By the way, if a restorer aimed to
power the filaments of such a set from
“D” cells, a pair of alkaline cells would
give up to 150 hours before dropping
to the cut-off voltage of 1V.
The much larger dry battery packs
designed for household receivers
would have lasted much longer than
the 745/482 combination. In fact,
some combinations may have had an
operational life of around 1000 hours
or more. However, I have no means
of being entirely sure of these figures
(or the other figures quoted above), as
I haven’t actually put this to the test.
Battery receiver power
Providing battery power for early
portable transistor receivers is not
Valve radio
batteries were
typically quite
large and were
not cheap.
88 Silicon Chip
siliconchip.com.au
an impossible task. For example, 216
batteries are still used in many transistor receivers and myriads of other
electronic devices. They can often
be used in transistor receivers where
much larger batteries were originally
specified.
Of course, the life of the 216 will be
noticeably less than the battery it is
replacing. The 276P was a commonly
used battery but is rarely seen these
days. However, WES Components
in Ashfield NSW have 276 batteries
with adaptors to convert them to the
276P type.
Alternatively, you can often use several AAA, AA, C or D cells in multiple
cell battery holders if a 216 or a 276
battery is not appropriate.
Battery-powered console, table and
mantel radios that used 2V accumulators and three 45B dry batteries in
series are a different story, as suitable
batteries are no longer made. However,
such sets can be operated from a mains
power supply that’s been designed to
deliver the necessary DC rails at the
required current.
Another way of powering such sets
is via DC-to-DC inverters. These are
typically designed to work from a 6V
or 12V lead-acid battery. This method
is closer to the original method of
supplying power, as the receiver is
independent of the mains.
Valve portable receivers
Valve portable receivers provide a
much greater challenge. Certainly, a
mains type power supply will do the
job but this means that the set can no
longer be used as a portable.
A cumbersome method of supplying
the HT voltage is to string together the
requisite number of 216 batteries. Ten
9V batteries in series to supply 90V
does look a bit odd though! Similarly,
alkaline D cells can supply the filament voltage quite easily.
A better method of supplying the HT
rail is to use a DC-to-DC inverter that
will fit inside the receiver. However,
this can be quite a challenge with the
small miniature receivers of the late
1940s, although the full-sized portables shouldn’t pose too many problems. The filament supply can still be
supplied by heavy-duty alkaline cells,
with the inverter supplying just the HT
requirements of the receiver.
Supplying bias to battery sets is
comparatively easy as no current is
usually drawn from these supplies.
siliconchip.com.au
Typical Eveready Battery Types For Valve & Transistor Radios
Type
Voltage
Comments
Bias Batteries
794
9V
714
4.5V
W95
9V
761
4.5V
Tapped bias battery
Battery to suit “baby” pedal radio
Bias battery tapped at -1.5, -3, -6 & -9V
Bias battery tapped at -1.5, -3 & -4.5V; uses 3 ‘D’ cells, 100 x 35 x 87mm
Low-Tension Batteries
X250
1.5V
30 x ‘F’ cells; companion to the older and larger 470
745
1.5V
8 x ‘F’ cells, 270 x 34 x 97mm
739
9V
717
7.5V
Battery for series-wired portable set filaments; uses 6 x ‘F’ cells
Filament battery; 5 x ‘C’ cells
–
1.5V
Large battery; same size as the 45V 770
High-Tension Batteries
467
67.5V
45 layer type cells; 72 x 34 x 90mm
482
45V
Layer type construction; 90 x 43 x 138mm
470
45V
Large 45V battery, newer type; 126 x 100 x 148mm
770
45V
Large 45V battery, 22 times the volume of the 467
Transistor-Radio Batteries
286
9V
2 x 276P batteries in parallel, 62 x 50 x 180mm
276P
9V
62 x 50 x 90mm
733
9V
57 x 52 x 90mm
2362
9V
33 x 25 x 76mm plus terminals
2364
9V
216
9V
2761
9V
2582
2 x 6V
2510
2 x 7.5V
2512
2 x 9V
Miniature transistor battery
General Purpose Batteries
742
1.5V
4 x ‘F’ cells
509
6V
4 x ‘F’ cells
X-71
1.5V
1 x ‘F’ cell
703
4.5V
Bias and general purpose battery
–
3V
A
1.5V
2 x ‘E’ cells cycle battery
Small general-purpose cell
C
1.5V
Small general-purpose cell
D
1.5V
Medium general-purpose cell
E
1.5V
Medium general-purpose cell
F
1.5V
Medium general-purpose cell
6
1.5V
Large telephone & general purpose cell; 17-30Ah capacity, depending
on use
Composite Batteries
759
1.5V & 90V
Sometimes, the original batteries in
30-50 year old receivers still supply
nearly the correct bias voltage (they
will not supply any current though).
Basically, it’s just a matter of using
suitable small batteries to do the job
(AAA or 216-size batteries may suit
individual receivers).
March 2008 89
Photo Gallery: AWA Empire State Radiolette
PERHAPS THE MOST FAMOUS RADIO made by AWA, the “Empire State” Radiolette was first produced in 1934.
It was housed in a bakelite case and came in a variety of colours including black, brown, marbled white and dark
green. A black Model 28 (1934) and a marble Model 32 (1936) are shown here. Both are 5-valve superhet receivers
and the valve line-up was as follows: 6D6 RF amp, 6A7 converter, 6B7 IF/AF amplifier/detector, 42 audio output and
80 rectifier. Photo supplied by the Historical Radio Society of Australia Inc (HRSA), PO Box 2283, Mt Waverley, Vic
3149. www.hrsa.net.au
Most portables use 1.5V, 7.5V or 9V on
the filaments, while the HT requirement is usually either 67.5V or 90V.
Obtaining a battery eliminator
An assortment for bias batteries from Eveready, Diamond and Impex. Note
the multiple output terminals on each battery, to enable the correct bias
voltage to be selected.
A mains power supply or a DC-toDC inverter supply can also be used to
power non-portable battery-operated
valve radios. This should be relatively
straightforward, as space is not usually
a problem in such sets.
90 Silicon Chip
In practice, a mains supply can
either be designed specifically for particular receiver or designed to supply a
range of voltages to suit many different
receivers from the 1920s to the 1960s.
The same goes for DC-to-DC inverters.
So where do you obtain a suitable
mains-powered battery eliminator to
run a vintage radio? Well, I currently
have a suitable design on the drawing
board to be published later in the year.
This unit will supply filament voltages
of 1.4, 2, 3, 4, 5 & 6V at 1A or so and
7.5-9V at 50mA. It will also supply HT
voltages ranging from 22.5V to 135V
and there will be a good selection of
bias voltages as well.
Suitable DC-to-DC inverters were
rather thin on the ground until Tony
Maher of the Historical Radio Society of Australia (HRSA) designed a
number units in 2001. His first item
was designed to replace a 467 battery.
It fits into the same space as the battery and is powered by four nicad or
NiMH cells.
He has since added a 2V supply
for sets using 2V valves and is about
to publish a 90V version of his 467
battery-sized supply in Radio Waves
SC
(the HRSA in-house magazine).
siliconchip.com.au
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