ISO Tango Transformer Core direction

[ngoyette]

I have the ISO Tango model FC-12S transformers for my 2A3 build that I am about to start.

I am having trouble identifying the direction of the Iron Core, I need to put the Power Transformer fairly closed to the output transformers and I want to make sure I put the Power transformer at 90 degrees to the output transformers to avoid any hum, but I have no idea where the Iron core is on the ISO's. They are Potted, so I don't know what to do. I have asked the distributor, his answer was:

"The output transformers are "potted" so it's not an issue compared with channel frame transformers. Primaries in the front. Secondaries in the rear"

does anyone have any advice on how to move forward?

Thanks

 

[gadget73]

Guessing the lamination stack will be in the wider dimension, so I think you'll want short side towards the power transformer. This is very much a guess though.

The external can probably does make this much less of a concern. At least thats what I'm hoping for after realizing I screwed up the mounting on the power transformer for something I'm building. Its 90 degrees from where I think it should be, so I'm hoping that distance and the can are going to save me.

 

[TriodeLuvr]

It's the plane of the windings that matters. The windings can be positioned one of two ways on an E core, and if only the outer edges of the laminations are visible, the direction can't be determined by sight. I've had to do this several times in the past by positioning the two transfomers next to each other on the bench. I apply AC to the power transformer, then monitor the induced AC at the output transformer with a scope as it's moved around.

Jack

 

[ngoyette]

It's the plane of the windings that matters. The windings can be positioned one of two ways on an E core, and if only the outer edges of the laminations are visible, the direction can't be determined by sight. I've had to do this several times in the past by positioning the two transfomers next to each other on the bench. I apply AC to the power transformer, then monitor the induced AC at the output transformer with a scope as it's moved around.

Jack

That is a great idea Jack, I will give it a try

 

[ngoyette]

That is a great idea Jack, I will give it a try

Does it matter if there is nothing connected to the power transformer secondary? I will make sure the secondary wires are not touching anything

 

[TriodeLuvr]

I don't load the secondaries, but I do tape them off to prevent accidents.

Jack

 

[ngoyette]

I ended up using my Dyanco M3 for the Power transformer and I put the ISO transformer next to it and measured the signal at each orientation, the photo below is the best orientation (Lowest signal level). Thanks for the tip.

 

[fxer1982]

I have a question for you, are these transformers for SINGLE ended as it is printed SINGLE on the bottom of the ISO transformers I"ve seen before for ISO single ended, im asking because you using a push/pull amp just to express the orientation of the Lamination of the output. If your building a single ended your all clear with this output transformer. if push/pull ummmmm ? I understand your testing for hum, possible distortion, If I'm interfering in your testing of a single ended transformer you already know its a single ended output Transformer just set up for winding testing . No disrespect intended to your intelligence on tube amps just trying to give my 2 cents in to help & not disruption your amp to be built... may she sing great for you...

 

[ngoyette]

I have a question for you, are these transformers for SINGLE ended as it is printed SINGLE on the bottom of the ISO transformers I"ve seen before for ISO single ended, im asking because you using a push/pull amp just to express the orientation of the Lamination of the output. If your building a single ended your all clear with this output transformer. if push/pull ummmmm ? I understand your testing for hum, possible distortion, If I'm interfering in your testing of a single ended transformer you already know its a single ended output Transformer just set up for winding testing . No disrespect intended to your intelligence on tube amps just trying to give my 2 cents in to help & not disruption your amp to be built... may she sing great for you...

I am building a single ended 2A3 amp.

it’s always good to inform people in case they don’t know on this site, you never know what people are thinking.

 

[fxer1982]

I am building a single ended 2A3 amp.

it’s always good to inform people in case they don’t know on this site, you never know what people are thinking.

thank you for understanding i saw they were single ended and wanted to ask only not try to beat ya up. and you replyed very humble to me i thank you for that...again may they sing very outstanding too.

 

[StepheK]

I ended up using my Dyanco M3 for the Power transformer and I put the ISO transformer next to it and measured the signal at each orientation, the photo below is the best orientation (Lowest signal level). Thanks for the tip.

Thanks for the follow up, and those transformers with a 2A3 are a good combo. My testing with them was the 3.5K option gave a good bit less distortion with a very small loss of power, like maybe 0.2W and in the end gave more usable power, unless you enjoy a lot of distortion. Might depend on the operating point but it's worth testing!

 

[ngoyette]

Thanks for the follow up, and those transformers with a 2A3 are a good combo. My testing with them was the 3.5K option gave a good bit less distortion with a very small loss of power, like maybe 0.2W and in the end gave more usable power, unless you enjoy a lot of distortion. Might depend on the operating point but it's worth testing!

I was planning on the 3.5k option, but I will check out the 2.5k to see the difference, thanks for the suggestion.

 

[dsndblm]

20 years ago, a friend and amp builder showed me a trick that works every time.
Place your power transformer in the location where you want it mounted. If the P/T is already mounted, you're half way there.

If the power transformer is mounted, remove the rectifier tube, or remove the solid state rectifiers.
Tape the output transformer primary windings.
Attach a headphones or a scope if you have one to the output transformer secondary windings.
I then power up the power transformer to 60% or so with a variac. No need for full power as you have no load on the transformers. Move the output transformer listening to your headphones for ac coupling, or watch the scope. Orient the output transformer for lowest coupling. The OPT placement isn't always the best for looks but the amp won't have coupled transformers.