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Post by trombone on Nov 18, 2022 19:34:14 GMT 12
Hi everyone ,
An old t.r.f. has come across my bench. It looks as if it might be a homebuild or a kitset. All the valve sockets are held in with nuts and bolts, the holes for the sockets cut with a valve socket punch which has also been used to cut clearance for the venerable transformer. I am keen to date this set and have checked both "The N.Z. Radio Guide 1933 " and "The N.Z. Radio Guide 1934 " looking for circuits that use this set's valve lineup.The valves are 35 , 35, 24A ,47 and 80.The first three valves turn up in a lot of sets around that time but the 47 seems to have enjoyed only a brief "time in the sun".Does anyone have info on when this was?If I know this that will help me narrow my search.The set is not specially complex but sometimes its nice to find the circuit in an old publication to get a feel for what it was all about. Thanks all and cheers,
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Post by DHockey on Nov 19, 2022 10:23:45 GMT 12
The 47 was introduced in 1931 and became quite a popular output tube. I have sets in my collection from 1931, 1932 and 1933 that use the 47. By late 1933 and into 1934 the 47 had been largely superseded by the 42 and 2A5, which being indirectly heated did away with the need for a centre-tapped filament winding on the power transformer.
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Post by trombone on Nov 19, 2022 17:46:58 GMT 12
Thank you . Exactly what I was looking for. I have some old copies of "The N.Z. Radio Times " of about that vintage and I will start there. Thank you again.
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