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Need diode for antique radio

S

SweenyAmp

New Member
I am restoring a Concerton U547 tube radio from 1957. I need a diode marked SR 250 Y 130. Or a suitable replacement. I dont have a schematic or parts list. Its a very rare radio made in Sweden. Thank you for any help you might offer.
 
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I believe that is a your basic selenium rectifier, where is it being used in the circuit?

If in the power supply, it can be replaced with a 1N4007 silicon diode or UF4007, use 4 of them if this is a bridge rectifier.
 
SweenyAmp said:
I am restoring a Concerton U547 tube radio from 1957. I need a diode marked SR 250 Y 130. Or a suitable replacement. I dont have a schematic or parts list. Its a very rare radio made in Sweden. Thank you for any help you might offer.
Click to expand...

1N4007

Available almost everywhere, autema i södra sandby t.ex.
 
If it is a selenium rectifier and you replace it with a 1N4007, you will probably need a resistor to drop voltages back down. 22-68 ohms at 5 or 10 watts should probably do it, but you may have to experiment.
 
Thank you! I will try a 1N4007. This radio is very strange, in that it only has 1 diode, and it is not a bridge. Its only a half wave power rectifier for the entire radio. I didnt know they made radios without full wave rectifiers. It has 7 tubes all total and 4 speakers.
 
You find that on series string rigs that run straight across the power line. Be careful, it may have the chassis tied straight to one side of the power cord.
 
in the USA, 1N34 diodes are probably most popular. There are also some European germanium diodes that you see in non-USA projects
 
New Diode

I installed a 1N4007 diode (only 1) and a series 150 ohm resistor. It drops 8V across the resistor. I also replaced all the big caps in the radio. It powers on! But it wont pick up any AM or FM stations. Just static. I dont know how to do an alignment. Guess I will have to take it in to a shop. Thank you all very much for your help.
 
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Check the resistors in the set, pull each tube one by one to clean it's pins and the sockets. Also make sure the correct tubes are installed. I've run into that one a couple of times.
 
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