20. Tubed Battery Radios

We often think of tube radios as mains powered radios, but historically spoken, battery operated radios are older. When amateurs experimented with radio around 1920, it was with battery operated tubes. And also the first factory built radios were operated from batteries. The heaters were fed from car batteries and dry batteries were used for the plate supply. Later came battery eliminators, which basically were seperate high tension units, and by the end of the nineten twenties all factory radios had such a unit built in so that the mains operated radio was born.

Rise and Fall of Battery Radios in the Fifties

Of course, there have been battery operated sets all the time, because of people who wanted to use their radio where no mains socket was around. But because of the high cost of operation, this was not very popular until after the second world war and we can say that battery radios florished from circa 1948 until 1958.

The start of this era was made possible by two developments. First, the war, besides a lot of misery, had simply brought us better battery tubes and there were large surplus supplies of these. The miniature tubes like DK92, DF91, DL41 were light weight and used little power. Second, there were enough people with enough money who wanted to enjoy radio during a camping holiday or a picknick trip. Radio had evolved from a luxory to a part of everyday life. Because of these two reasons, the operation cost of battery radios was no longer prohibitive for their development. The end of the battery tube radios came, of course, because of the introduction of transistorized radios.


Battery radios are usually classified into three types.

Portable Sets

These are the radios that one takes on a trip and carries along to hear radio in the woods or on the beach. Portable radios are supposed to be small and leight. Also their batteries are small, so they must have low power consumption. The plate batteries are often 67 or only 45V, and the output power can be as low as 100 or 50mW, so a highly effective speaker is required.

Simplicity is the key word with these receivers. They are usually equiped with four tubes and often have only medium wave, though sometimes also the long wave band is found. The photo on the right shows the Highness of 1954, I have in my collection also a Tesla Minor (with short wave) and an Eveready (big with long wave).

Stationary Sets

Much bigger radios were used by people simply at home; in the fifties there were still places in our country where no mains power was available. Think of farms, but also of ships and recreational bungalows. These radios were not carried around, so they could be heavier. Also, in their house people didn't like to compromise with reception quality, so these radios were multi-band and often had push-pull output stage. An outdoor areal could be connected. The batteries of these radios were the largest (right are those of the Philips LX381B).

A stationary receiver in my collection is the Decca (photo). The Philips LX381B also comes close; it was made as a portable receiver, but is a quite heavy one and has three bands and balanced output. Basically, it is a carried version of the stationary BX484B (but with a loop antenna built in). For a later example of a stationary set (with eight tubes), see the Philips BX439B (1954). The battery economy of the later models was close to the unimaginable; the entire radio, with eight tubes including a magic eye, consumes less than 1 Watt of electrical power.

Universal Battery Sets

The most common type of battery radio is the mixed set, that could be operated from both batteries and mains. This way, the radio could serve as a battery radio in the holidays, but could be used as a second set in the house during the winter. Power consumption was not very critical (because the set was used from the mains most of the time!) and the radios could often be seen with extra tubes. The Perfecta on the right has an RF stage, some radios had a tuning indicator.

Besides the Perfecta, I have a Schaub (MW, LW, Phono), a Vega Turist (four band), a Vidor Lido. A very nice piece is the Philips L4X71AB, which tunes the FM band; this type was still sold in 1958 and 1959 because the new transistor radios were not yet able to receive these high frequencies.

A later, very nice addition to my collection is the Zenith TransOceanic of 1947, with 8 tubes. This radio is triple powered: for mains you can choose between AC and DC (but not between 110V and 220V; use in Europe was not foreseen). These so-called universal radios mostly have the filaments in series, and because the tubes are directly heated, this causes the cathode currents and filament currents to cross. Some extra resistors at the cathodes are necessary, and if you are not aware of this, the whole arrangement is difficult to understand.

Some of the universal sets are dual powered (Battery and AC) and have a power transformer. Some are triple powered (Battery, AC, and DC).

A common misunderstanding about the combined battery-mains radios is that some can charge their batteries. The dry batteries that were used in the fifties could not be recharged after use! However, it was found out that battery life was shortened by the formation of hydroxyde bubbles, a process that could be reversed by sending a small reverse current through the battery. So, many of these radios had a CHARGE button to do exactly this. Incidentally, a radio could have a NiCd filament battery that could be charged.

There is one thing you'll never find in a battery radio: dial illumination, at least not one that is on continuously. The power consumption of a single dial lamp equals the consumption of two or three tubes in the HF section! Few people like to pay for batteries wasted in this way.

Batteries for tube radios

The radios were originally designed for the use of dry batteries, and sometimes you find one in a old radio. The left picture (by Jobakker) shows a filament battery (f4,40) and a plate battery (f8,85) from a Philips L3X81B. Some people also use dry batteries for their vintage battery sets, but I enjoy the use of NiMH rechargeable batteries a lot. For small and big radios, this is a good option.

The lower voltage of rechargeable batteries is no problem at all. Dry batteries (Which the designer had in mind) have a considerable internal resistance, which means that the voltage they give, decreases when current is taken from them. Put otherwise, a 90V plate battery gives 90V of voltage when it is new and no current is drawn from it.
Picture Type, Year Sound
Zenith TransOceanic
Philips LX381B
Philips LX422AB
Philips BX439B
See more battery sets
When the battery ages or current is taken, the voltage decreases to 70 or 60V. Radio designers knew this, of course, and designed radios such that they had good performance on voltages as low as 70% of the nominal battery voltage. Rechargeable batteries have neglectable internal resistance: their voltage stays constant until they are empty. For the filaments of the modern miniature tubes, that take 1.4V nominally, this means that a 1.2V NiMH cell gives sufficient voltage to supply them. Because of the low internal resistance, a single AA cell can deliver enough current to supply a 6 tube set (300mA) like the Philips LX381B. Most of the sound recordings that you can play on the right were made with such batteries.

In practice, I use two AA-cells in parallel for the filament, to have an acceptable battery life time. After about 20 hours, they can be recharged in a standard charger. The plate battery, consisting of six to ten P-cells in series, takes a lot of time to be charged in a standard charger; it takes only one or two batteries at a time. In May 2008 I built a special purpose charger for the 90V high tension battery. It charges the entire block of cells in one charge, taking about 24h.

On the left picture you can see that the space in even portable radios is usually sufficient to house a pck of six 9V rechargeable cells. If the space in a small set would not be sufficient, you can try to use just four, because I have observed that radios can play on a voltage as low as 25V. Of course, sensitivity and output volume suffer from this. The right picture shows the pack of 6 P-cells in action inside the TransOceanic, together with a single 9V cell for the filaments.

Other battery equipment

Military Equipment

The army always used a lot of field equipment powered from batteries. On the right you see a frequency meter from WWII, on the left a field receiver from the nineteen fifties.

Hearing Aids

The smallest and most economical tubes that I know of were used in hearing aids. During the thirties deaf people had to carry around small boxes with battery operated tube amplifiers, but in the early fifties an entire tube amplifier, with microphone and batteries, could be included in a pocket-carryable box as big as a deck of cards. This Blaupunkt has three tubes, powered from a penlight battery and a 22.5V photo battery. Tube technology didn't get as far as equipment that could be carried in the ear, as nowadays transistorized hearing aids can.

A remote control with battery tubes existed as early as in the nineteen thirties (it controlled a radio because TVs were not around yet). A special type of battery tube was produced for weather balloons; they had a catalogue life span of 5 hours.