Radford STA 12 Rebuild

[snowman_al]

Hi Everyone,
I'm new to posting on Aos so please treat me kindly. And I hope I have chosen the right place to post... So here goes.

As a long time fan of Radford, I recently acquired a very sad STA12.
This one had suffered more than most. Clearly in the past it had had the reservoir/smoothing cap explode. There was sticky residue and flakes of paper and foil under everything. I guess that was the start of 'someone' fixing it up and 'modifying' it. Triode connected outputs and shared cathode bias resistor, components dangling on bits of wire and so on.
Then it had clearly been dropped and the transformer chassis badly bent together with the outer frame.

Only one thing to do, a total rebuild. This is where I am to so far, the is chassis stripped, cleaned and straightened:-




I'm missing a few parts, especially an output transformer, so please look out I will be on the scrounge!
Alan

[brian2957]

Hi Alan , welcome to AOS . I'll be watching this thread with interest

Enjoy the forum

[spendorman]

Very interesting. I shall be following too.

I wonder if Radford Revival can help.

I'm a long time owner of an STA25 III, probably more than 40 years.

[walpurgis]

I wonder if Radford Revival can help.

That idea crossed my mind. I'd expect they'd have some spare parts and could possibly match the enamel too for touching in purposes.

[IHP]

That idea crossed my mind. I'd expect they'd have some spare parts and could possibly match the enamel too for touching in purposes.

Beautiful work Alan. May I please ask if you got a result on the matching enamel ? I have a 25 in lovely condition but with 2 minor blemishes on the casework I'd like to touch up. Airfix don't seem to do a 'Radford blue' !

[snowman_al]

No sorry I did not. I decided to leave it 'as is' to show some of its age...
I have a metal plate for the bottom now so will give that a coat of something close from Halfords or the motor factors. It does not need to be perfect, it will be underneath.

The other thing is that it is totally different in colour to my STA15 III (which is two tone and I guess will be similar to your 25). The closest picture to the real STA12 colour is the 'rear view' (one from last) the white balance on my camera is not the best.

I have found that the Humbrol (or Airfix) enamel actually can be mixed to match lots of things with a bit of time so that might be the way to go if the areas are not too large or obvious?

Alan

PS thanks for the comments everyone.

[snowman_al]

Guy's thanks for the Radford Revival tip, and Will says, ''rarer than hens teeth!''
My best bet will be a pair of later T2063s, anyway I've put a Wanted Ad up just in case.

[walpurgis]

It's worth keeping an eye on ebay. There may be a compatible transformer from a non Radford design, although obviously an original would be desirable.

[spendorman]

Rare, yes, but I would have thought an STA20 was even rarer. I just happen to know someone that owns one! (not me).

[spendorman]

Circuit diagram here:

http://www.audiomisc.co.uk/HFN/Radfo.../circuits.html