At the Radio Nostalgia event in Uedem, Germany, VOA Radiogram listener Dr. Georg Niepel demonstrated the decoding of VOA Radiogram content, using audio from a Graetz Musica 4R 417 radio, built in 1957. The following is from Dr. Niepel’s website, http://www.radio-hobby.de/ …

VoA radiogram can be received with every normal shortwave radio. Instead of an external speaker or a headphone, you just plug in a connector cable in order to bring the audio signal to your computer. By the way, I wanted to know whether it would work well, even if we would use an old-fashioned tube radio.

The Graetz Musica 4R 417, built in 1957, is an AM/FM superhet tube radio using an ECH81 (6 AJ 8) with a triode for the AM oscillator and a heptode for mixing, followed by an EF89 (6 DA 6) for the IF amplifier stage. AM-demodulation and audio-frequency-preamplification is done by an EABC80 (6 AK 8 / 6 T 8), followed by an EL84 (6 BQ 5) as power amplifier.

This means that the circuit is a rather simple superhet without HF preamplification and with a single IF stage only. Nevertheless, due to the use of tubes, the selectivity and the sensitivity are good enough for clear shortwave reception.

During the presentation of old-fashioned radios on the “Radio Nostalgia” event in Uedem, Germany (Saturday 9th of May, 2015), I received and decoded VoA Radiogram “live” using this Graetz radio, connected to a laptop computer. Four meters of indoor wire antenna were spread out, and after admitting twenty minutes of warm-up, tuning was stable on 17870 kHz. At 16:00 UTC when the transmission began, about a dozen pairs of eyes stared onto the laptop screen.

Picture decoded on 9th of may 2015, using the old-fashioned tube radio …

Well, I must confess that some pixels are distorted, but we could demonstrate that VoA Radiogram can be decoded using an old-fashioned “boat anchor”.

Kim: At the Radio Nostalgia event, the text from VOA Radiogram decoded at least 90% correctly. Here’s an example …

I think that the errors would be attributable not to the Graetz radio, but to the “four meters of indoor wire antenna” in what was probably an electrically noisy environment. Also keep in mind it is about 6500 km from the North Carolina transmitter to Uedem. (The GE transmitter was manufactured in the early 1960s, not long after the receiver was built.)