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#1
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Good Day All!
Have recently aquired a "homebrew" receiver which I am trying to upgrade and fully restore to working order. In the back of my mind I am quite sure that it was a published design possibly in "Electronics Australia" or similar back in the 1960's or early 70's. It is a 6 valve/tube design using an ECF82 first mixer/oscillator (1st if about 4 Mhz) , a 6BE6 Pentagrid second mixer/osc, originally with varactor fine tuning down to 455 KHz. 2nd oscillator on about 4.5 Mhz. It then has 2 stages of 455 KHz IF originally using EF183's with 2 IF transformers per stage, a total of 10 tuned circuits at 455 Khz. This is followed by a 6BE6 product detector/BFO (Drake style) or a diode for AM rception and an ECL82 for audio stage and output. It has 4 bands from about 3 MHz to 30 MHz. Does any one remember coming across this circuit? It has some rather eccentric features like IF neutalisation and a VERY lossy coupling between IF stages. Any information gratefully received as I would like to 1. find an original circuit. and 2. Find out why some of the peculiar design details were used. Hope it rings a bell with someone. 73's Cliff Wright ZL1BDA ex G3NIA |
#2
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On Jul 7, 4:55 am, cliff wright wrote:
Good Day All! Have recently aquired a "homebrew" receiver which I am trying to upgrade and fully restore to working order. In the back of my mind I am quite sure that it was a published design possibly in "Electronics Australia" or similar back in the 1960's or early 70's. It is a 6 valve/tube design using an ECF82 first mixer/oscillator (1st if about 4 Mhz) , a 6BE6 Pentagrid second mixer/osc, originally with varactor fine tuning down to 455 KHz. 2nd oscillator on about 4.5 Mhz. It then has 2 stages of 455 KHz IF originally using EF183's with 2 IF transformers per stage, a total of 10 tuned circuits at 455 Khz. This is followed by a 6BE6 product detector/BFO (Drake style) or a diode for AM rception and an ECL82 for audio stage and output. It has 4 bands from about 3 MHz to 30 MHz. Does any one remember coming across this circuit? It has some rather eccentric features like IF neutalisation and a VERY lossy coupling between IF stages. Any information gratefully received as I would like to 1. find an original circuit. and 2. Find out why some of the peculiar design details were used. Hope it rings a bell with someone. 73's Cliff Wright ZL1BDA ex G3NIA No: But I vaguely remember a QST article of the 1950s? about a receiever that used many 'stagger tuned'? IF circuits to get bandwidth suitable for amateur work? Also IIRC it was an American husband-wife team who wrote the article? Terry |
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