05-22-2007, 08:41 AM
Hi Dave,
I am sure you then would know how to build a suitable supply. I forgot that was rated for 220V but I recall only the ballast tube was different. A type 3 was used in the 220 volt set and a type 2 for 110 volts. Of course finding the correct 110 ballast tube would be as difficult as finding 14 and 17 tubes for it. Fortunately 110 to 220 volt transformers are easy to find. The biggest problem I had building a supply for my AK 41 was getting a filter choke with enough impedence and a big enough current rating. I don't play it hours at a time. I am using a filter choke out of an old TV that has a 250ma rating which is just at the limit so it gets a little warm after a while. My set uses five 112A and two 71-A tubes which draw 250 ma and a little more for plate current. With a simple pi filter, I only got 90 volts out of the supply so I use an isolation transformer with a voltage tap. That way, I can get it up to 115 volts DC. The only other DC set I had years ago was a Radiola 33DC with the matching 100B speaker and the optional legs. Sorry I sold it now.
Fred
I am sure you then would know how to build a suitable supply. I forgot that was rated for 220V but I recall only the ballast tube was different. A type 3 was used in the 220 volt set and a type 2 for 110 volts. Of course finding the correct 110 ballast tube would be as difficult as finding 14 and 17 tubes for it. Fortunately 110 to 220 volt transformers are easy to find. The biggest problem I had building a supply for my AK 41 was getting a filter choke with enough impedence and a big enough current rating. I don't play it hours at a time. I am using a filter choke out of an old TV that has a 250ma rating which is just at the limit so it gets a little warm after a while. My set uses five 112A and two 71-A tubes which draw 250 ma and a little more for plate current. With a simple pi filter, I only got 90 volts out of the supply so I use an isolation transformer with a voltage tap. That way, I can get it up to 115 volts DC. The only other DC set I had years ago was a Radiola 33DC with the matching 100B speaker and the optional legs. Sorry I sold it now.
Fred
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