Metropoulos Forum

I would like to build a replica of 784-139 OT.
I've looked all over the net to find all details but I've collected just few info.
I know that these are considered precious secrets and people are doing their business with it ... anyway I try
Here the result of my search, as you can see I miss a lot of info

- winding pattern it seems to be: 0.25 PRIMARY || SECONDARY ||0.5 PRIMARY || SECONDARY ||0.25 PRIMARY
- primary should be 1760 windings, diam 0.31mm
- So I should have: 440 turns PRIMARY || SECONDARY || 880 turns PRIMARY || SECONDARY || 440 turns PRIMARY
- About secondary windings: I dont know if they are connected in series (two windings of 60 turns) or in parallel (like dagnall C1998, so two windings of 120 turns, first 0-16, second 0-4-8-16) and how they are distributed.
- I don't know even secondary diameter, doing some math it should be 1.08mm, but I would like to know exact diameter
- About iron it should be classical "I-E" 96mm x 80mm, 58 laminations x 0.65mm (tot 38mm)
- For iron type I should go for M6

Moreover: I dont know the meanings of "self leads" or " flying leads", can you explain me?

I hope that someone will give me missing infos or at least confirm what I found (even directly to my email)
If not.................
I will buy another great OT from Bryan

just buy one in the store.

thanks a lot for your suggestion .... very precious
The main problem is that I live in Europe and if I buy a Marstran, Metro or Mercury OT I spend a lot of money in shipping and tax and moreover USD dollar is growing up....
I dont want to wind coils by myself I'm not crazy. My goal is to collect all the specs and give them to a professional maker I know. This man has been building tranformers for 30 years but unluckily he builds HI-FI stuff.

I found on a russian site this schema for OT100W 1998
No way to find winding schema for 784-139.
About the schema attched, can someone tell me at least if this is correct?

I hate to say it but given the time and effort you have spent on the net trying to get an answer, you could have just done a tear down on a real OT yourself and been done with it.

Brian Wallace wrote:I hate to say it but given the time and effort you have spent on the net trying to get an answer, you could have just done a tear down on a real OT yourself and been done with it.

Brian, you didn't get the point: this is not my business, this is my hobby, I've built 4 amps in my life ...
So if I spend 200 USD (150EUR include shipping, tax etc...) to buy your OT replica, for sure I will put it on my plexi clone I'm building and play it loud! The last thing I would do is to tear it down
I'm just trying to get the same thing (or a similar thing) for less than 50EUR.

Anyway I'm givin up..

P M george maybe he will give ya the specs. I thought our dollar was regressing to its childhood.

@ flatart

People, who can't say a nice "hello" or something similar in their very first post show oneself as pure cadger and hence can't expect much help of the other, who always help each other

Think about this for a minute