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.
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).
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.
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.
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.
|PLAY||Zenith TransOceanic |
|PLAY||Philips LX381B |
|PLAY||Philips LX422AB |
|PLAY||Philips BX439B |
|See more battery sets|
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.
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.