Metropoulos Forum

Started this project a few weeks ago, need help with the secondaries of the OT. I bought the OT from NYChief 4 years ago and he bought it from George. I called heybuer and they were not able to help, but they did say it was made in 2005.
The Marstran web site shows primary wires with same color code as my OT, but the secondaries are different. So need a little help

If you put a meter on them you can work out the inner and outer

A DRAKE 1202-119 should be:

Blue - 16
Green - 8
Yellow - 4
orange - ground

You seen to have the colour codes for a Dagnall (brown ground, black 4, yellow 8, green 16) I would ring those out with your meter.

Neikeel, can you remind me how to do that.

axeman wrote:Neikeel, can you remind me how to do that.

put you meter on ohms.

start by using brown as ground (ie start of coil) and then measure between each wire and start. bear in mind the readings will be low you will get three different measurements. Highest reading will be the 16ohm (coil end), next the 8ohm and next 4ohm (which are less coils in the middle).

Remember you will not get those readings (4/8/16) just three different ones.

Thanks, I remember watching a video with Gerald Weber explaining how to do that and figuring out the impedance

Thanks Again

It's not working, i'm doing something wrong, can't figure out the impedence on the wires

axeman wrote:It's not working, i'm doing something wrong, can't figure out the impedence on the wires

What is your meter? Does it not have an ohms setting?

it does, I have to meters. I keep on getting a reading of 6 or 5 on all the leads

Weird.

I have a Marstran 789-84 (ok for a dual OT 100w but the principle is the same!) I will do this 'blnd'

I set my Fluke 115 to ohms (auto range).

I get:
0.2ohms orange-green
0.4ohms orange - yellow
0.6ohms to green - yellow
0.2ohms blue-green
0.8ohms to blue -yellow

From this I can extrapolate that the biggest difference is between blue - yellow, which means the ends of the coil are blue and yellow (yields 16ohm option, but which is common and which is 16ohm?
Next look for the next lowest which is 0.6 ohms between yellow-green which suggests that yellow is common and green is 8ohm, next is yellow orange suggesting orange is the 4ohm tap. I just checked this against the Marstran schem and it is reassuringly correct (phew!).

Suggest you check your meters out (and use croc leads, not holding with your fingers!

O.K. I got it done. Sent the OT to Mercury so they can ID the wires for me, free of charge. My primaries wires were wired incorrectly, i'm glad I sent it in. Now I am looking for the ISKRA that I need to complete this build.

axeman wrote: Now I am looking for the ISKRA that I need to complete this build.

Which is?

I need
2-100k
1-82k
2-220k
2-470k
1-15k
1-56k
1-47k
2-10k 2watt
1-8.2k 2watt

I've bought some Iskras from this guy before, he's good to deal with. He has a few of the values you listed and maybe a few you didn't (like 5.6k, 27k, 33k):

http://www.ebay.co.uk/itm/Vintage-NOS-I ... 1c48e9b951

Whazzgroover has 470k in 1 watt:

http://www.ebay.co.uk/itm/n-2-470K-1W-I ... 51aa855000

And he has 10k 1 watt:

http://www.ebay.co.uk/itm/2-RARE-10K-1W ... 1c489657f5

Love that chassis, where did you get it?

A machine shop made it for me. They where going to make 30 for me and nick from ceriatone was going to make the panels,
But had to cancel not enough buyers