Saturday, 3 August 2013

Vintage radios, all kinds of radios

I promised to write about radio hobby. Here we go. Yesterday I took photos of my collection, except those radios that are not available in my current residence.
This beauty I found in the rubbish collection few years ago. After cleaning it became one of my favourite radios. It does not work, but serve as a pretty piece of furniture. It is Philips Aachen Super D63. It was built by Philips Deutschland in 1939 or 1940. It weights 19,5 kg. The original price in 1939 was 394 Reichs Mark. It has 8 valve tubes. The technique is superheterodyne developed in the 1930's. It also has 7 tuned AM circuits, which means that you can quickly tune into your favourite station by pushing a button. There are buttons for Deutschland Sender, Luxemburg, Hilversum, Wien, Breslau, Stuttgart, Munchen and Köln. Very modern indeed.
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It is very interesting to read the radio station names on the tuning dial. Where were the most important radiostations in the 1930's? How far away people reached wireless more than 70 years ago, when there were no cellphones or Wifis!
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I bought this Sony ICF-SW22 some 15 years ago. It was my favourite take along radio for 10 years. It cost me 3000 Luxembourg Francs. Converted to euros it would be something like 70 euros. Reception is fantastic, crisp soung, good selectivity and sensitivity. I used to listen to far away radio stations from South America and Asia when walking in the forest. The reason for good selectivity is the dual conversion technology and high quality components usually present only in more expensive receivers. It is small, like a c-casette case (if you have ever seen one) or small cigarette box.
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This is Colton Six Transistor JT-602 pocket radio made in Japan. Probably built in the mid 1960's.It has only Medium Wave band.
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I love the design of this little green pocketable radio. It is called Expo'70 Micro Radio 9, manufacturer unknown, some sources propose that the building year is 1962. It looks cool also in the inside. The colours of the case were at least black, yellow and green. Of course it has only MW-circuit. Must have been really cool gadget in the early 1960's
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Tercsun R9710 is one of the small short wave radios manufactured in China. Link to Tecsun Those radios are cheap and the performance usually very good. After shortwave dxing as a hobby has been going down the last 20 years, the hobby has moved to more specialized directions. One of those special hobbies is so called "Ultra light dxing", where you are allowed to use only very small receivers and try to catch radio stations as far as possible. It requires skill and creativity. R9710 is one of the receivers that qualifies for "ultra light" series of receivers. Just like Sony ICF-SW22 it use dual conversion technology which means that it can reject unnecessary noise better and reception should be clearer. Very pocketable. Sales price at Ebay.com around 25 USD.
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Another Chinese pocket radio is Kaito WRX911. It looks awesome, but the reception is lacking if you don't expect too much. Sensitivity is good, but image rejection is not. It means that you may hear too many radio stations that don't exist. They are images of radio transmissions on another frequency.
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Radio technology is advancing. The biggest recent innovations in radio receiving technology is a new DSP (Digital Signal Processing) chip developed by Silicon Laboratories Ltd. The chip is called Si4734 and is used in most of the modern portable receivers. The new chip integrates in one integrated circuit the complete receiver function from antenna input to audio output. If it is implemented well into a receiver design, the Si4734 give a small portavle receiver an exceptional selectivity and sensitivity. And it is dirty cheap. DE1125 carry this new chip. It is also marketed under name Kaito KA801 (Kaito is a trade name used in America, trying to disconnect the product from its origin, China).
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Unfortunately the new Digital Signal Processing chip is NOT well implemented in this receiver. The reception on short wave is not pleasant. The radio is nevertheless very beautiful and includes a MP3-player.
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You may see a demo of DE1125 HERE. Audio is wonderful and design awesome.

Somewhat older model is Degen DE1105. It is one of the modern good looking receivers, that don't really work well on short wave, but it certainly is a nice peace of electorinics. It is a pocket sized FM Stereo MW, Dual Conversion Shortwave radio. It has 1,000 memories. It has a thermometer and alarm clock.
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Radio series will continue in the near future.


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