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A DIY Radford STA25 restoration

As previously mentioned briefly upthread the lugs/frames of all of the transformers and the choke are a bit distorted/bent out of shape. My guess is that the amp has been dropped at some point.

One of the OPTs:

P1110616 by Michael Pickwell, on Flickr

The choke

P1110617 by Michael Pickwell, on Flickr

And the mains transformer

P1110618 by Michael Pickwell, on Flickr

A session of metal bashing in the garage this afternoon has them looking much better

P1110631 by Michael Pickwell, on Flickr

P1110630 by Michael Pickwell, on Flickr

P1110629 by Michael Pickwell, on Flickr
 
I've started re-populating the boards but I'm still waiting in some parts to be delivered.

P1110647 by Michael Pickwell, on Flickr

The 4x 0.47uF film caps are new old stock vintage Wima MKS which are the same as those originally fitted.
 
They look good - if they are not originals they are pretty close. Much nicer than the gold plated ones you had before.

I think they're suitably no-nonsense and they fit perfectly. They even have the right little keyway/notch thingy for the hole in the chassis.
 
Nice job, that is going to be a superb amp! Always great to see quality kit like this de-botched and returned to exactly what it should be.
 
Too late for you Mike, but in case anyone else has to replace the selector switches here are my notes.
(The pencil numbers and letters correspond to a Lolin switch and the blue numbers to the impedances. The numbers in brackets are the transformer numbered connections)



Looking good bye the way, Alan
 
Can someone explain the diff amp? How do you get a balanced signal when one half is a pentode and the other is a triode? I kept looking to see if it was secretly a floating paraphase and I had somehow missed the feed to the triode grid, but it's grounded (at audio frequency) so it must be a diff amp.
 


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