Drake Transformer

Max_b3

I have a Drake mains transformer with a code 786 515 on it. Can't find anything on the net about it i.e. what it was used for, colour codes for the wires etc. Anyone have a clue?.

Thanks

ICBM

Not one I'm familiar with, from memory...

What are the core dimensions?

How many wires does it have, and what colours are they?

Do you have a multimeter?

Max_b3

Thanks for the response. It looks like a typical Marshall type

Core is 53x80x95mm
 There are 4 outlets on the bottom, 2 each side.
 outlet 1: 3 wires, orange, yellow and green with yellow stripe (like an earth)

outlet 2: 3 wires, red, black, and brown

outlet 3: 6 wires, a twisted blue pair, white with brown stripe, solid white, purple and pink
outlet 4: 2 wires, a twisted pair of greens (GZ34 heater?)

I have a multimeter.

thanks

ICBM

I can't get at my box of old transformers at the moment, but that sounds like a 50W PT I think. Drake have used quite a lot of different colour codes so it might be risky to assume anything...

Start by identifying which wires have continuity to any of the others, and what the resistances are - they could be up to a couple of hundred ohms if there's something like a bias winding, so I would probably start on the 2K range. The exit holes won't necessarily correspond to the wiring connections at all.

The blue and green twisted pairs will be opposite ends of the same winding so the first thing to do is check that is the case and then look for a centre tap, which they may have. There may not be a rectifier winding, they could be filament (probably green) and HT (probably blue). White and pink are often used for a bias winding.

There could be up to six connections on the primary winding if it's a multi-voltage type - if so orange and purple are likely to be the opposite ends. The 'earth' wire may well be an interwinding screen and not connected to anything else.

Max_b3

Thanks for your help, I'll check it out when I get 5 mins.