Manufactured by Zenith Radio Corp., Chicago, IL.
Ten years after Zenith had introduced the earliest „Trans Oceanic“ multi-band radio, the company introduced the H500, which had miniature valves fitted. 245'000 of these sets were sold, the H500 achieved the largest production figures of all „Trans Oceanics“ and is considered as the classic world band receiver of the early fifties par excellence by many collectors.
The possibility of battery and mains power supply, the circular dial, the various antennas (including the „Wave Magnet“, a medium-wave loop antenna) and the „Radio Organ“ (four switches to control the tone), the set had in common with its predecessors.
The H500 is a quite bulky tube-equipped all wave receiver. The set measures 43 x 28 x 20 cm and has a weight of 7 kg.
The receiver can be operated from special batteries (which are no longer available today) or mains power. In this point, you have to be very careful: the standard H500 version is designed only for operation from 117 V (U.S. mains voltage), the international Version one can be operated from 110 or 220 V by adding a voltage drop resistor, so check first before just plugging in a mains socket…
A metal clasp on the front unlocks the large hinged lid; when the set is complete, the WAVE MAGNET, a detachable shortwave - frame antenna is visible on the hinged lid, when opened the telescopic antenna must be pushed in.
The left third of the front panel is taken by the loudspeaker grille.
The right third of the front panel contains the pushbuttons that activate the various shortwave ranges and the mediumwave range BC (Broadcast Band). Conveniently, a label on the front panel right next to them indicates the time of day when the band is most suitable for reception. In the middle of the front panel the circular dial is located: the distribution of the dials for the shortwave broadcast bands in the upper and lower halves is confusing, to say the least, and takes a lot of getting used to. Especially the combined maritime communications and tropical band ranges 2-4 and 4-8 MHz with the broadcast bands marked in red and the fact that the 16 m band dial is found between the 120 - 80m and the 19m band dials contribute to general confusion. Medium wave frequencies are read on the white U - shaped dial below the 25m band dial. Long wave is missing as typically found on US sets; longwaves never have been used as a broadcast band in the USA.
The rotary knobs below the circular scale are the volume control and tuning knob. Four slide switches below the dial are the tone controls, the iconic four little switches TREBLE - VOICE - ALTO - BASS were retained throughout the entire model series of the tube-equipped early „Trans Oceanics“.
After the first hurdle is taken and the correct supply voltage is applied, the operation of the radio is uncomplicated. As a warning, I would like to add that the „Trans Oceanic“ is a „grandfather“ among world band receivers and a collector's item that needs to be treated with care: I recommend a first start-up with an isolating transformer after the set has been checked for capacitor defects, and after suspicious capacitors have been replaced if necessary.
The volume control is combined with the power switch, the push-buttons are used to select the desired shortwave band and the pointer is set to the approximate reception frequency on the circular dial. Now listen for the programme language and an interval signal or frequency announcement to identify the transmitting station. A BFO for CW or single sideband reception, selectable IF - filters, passband tuning and the like are not to be found on the Trans Oceanic H500, in the fifties such technical features were available only in a few professional communication receivers.
In summary, the Trans Oceanic H500 is an absolute classic among the tube „world band radios“, which - because it was built in large numbers and usually cherished by the owner - is not too rarely found for sale second-hand. Such a set is a great pleasure for the collector, but I would strongly advise against using it for travelling and recommend a double conversion set with a modern concept for shortwave DX, if you want to listen to more than just a few strong signals from the surrounding countries - but shortwave reception across the continents still is possible with an H500.
At this point I would like to thank Roy Johnson, who gave me his family heirloom and helped me to get the first „T/O“ in my collection.
Battery valve superhet with HF preamplifier stage.
1U4, 1L6, 1U4, 1S5 (or 1U5 in version A), 3V4