isolation transformer needed...

[tincan]

I have purchased a Superior TV-11 tube tester and need to add an isolation transformer to the circuit as it has an autotransformer from the factory. I can't seem to find what I need and not really sure what to look for. I'm only aware that using the tester with it's original autotransformer can be a potential shock hazard.

Can someone help out with this project?

Thanks...

[dieseljeep]

Originally Posted by tincan

I have purchased a Superior TV-11 tube tester and need to add an isolation transformer to the circuit as it has an autotransformer from the factory. I can't seem to find what I need and not really sure what to look for. I'm only aware that using the tester with it's original autotransformer can be a potential shock hazard.

Can someone help out with this project?

Thanks...

I never heard of that tester being a shock hazard.
It's probably a clone of the Eico 625.

[cbenham]

Originally Posted by dieseljeep

I never heard of that tester being a shock hazard.
It's probably a clone of the Eico 625.

The tester was made by Superior in 1951 and is not related to Eico.

Here is a 'review' of the device:
http://www.radiomuseum.org/r/superio...ter_tv_11.html

You probably have no fear of getting shocked with this instrument since you are plugging tubes into it for testing and not connecting it to anything else.

If you want an isolation transformer you can usually find something on eBay.

I'm guessing here, but a Triad N-51M isolation transformer is rated at 0.3 amps and 115 VAC in and Out.

This might be adequate for the tester but you'll want to look for the current and voltage rating printed on the tester, and you will want an isolation transformer of at least the same rating.
You will have to build this particular transformer into a box and add an AC plug wire and a socket to make it plug 'N play. Or you might be able to install it inside the tester. Will depend on how tight the internal construction is.
Best Luck!

[dieseljeep]

Originally Posted by cbenham

The tester was made by Superior in 1951 and is not related to Eico.

Here is a 'review' of the device:
http://www.radiomuseum.org/r/superio...ter_tv_11.html

You probably have no fear of getting shocked with this instrument since you are plugging tubes into it for testing and not connecting it to anything else.

If you want an isolation transformer you can usually find something on eBay.

I'm guessing here, but a Triad N-51M isolation transformer is rated at 0.3 amps and 115 VAC in and Out.

This might be adequate for the tester but you'll want to look for the current and voltage rating printed on the tester, and you will want an isolation transformer of at least the same rating.
You will have to build this particular transformer into a box and add an AC plug wire and a socket to make it plug 'N play. Or you might be able to install it inside the tester. Will depend on how tight the internal construction is.
Best Luck!

I never said the company was related to Eico.
I said it was a clone! All the simple emissions testers were simular in design. They all tied the elements together and tested the tube as a rectifier. The Heathkit, Knightkit and Eico, lower end tube testers were very simular.

[tincan]

I work on string instruments and sometimes have several tools plugged in and laying around on my bench at one time, so just wanted to be safe about it. That, and sometimes some of the "other" guys have a habbit of using my work bench when I'm not there and don't know what they may be up to. I'll look into the transformer mentioned and see if it will meet the specs for the tester. There is plenty of room to mount a transformer inside the case so no worry there.

Thanks for the info!

[Tubejunke]

I have a large Variac that I as of yet have found no way to use. Not anyting wrong; it just has oddball input and output sockets which I have no plugs for. This thing is pretty much top of the line for its time and I would like to use it, but I would sell if you are interested. Been trying to thin the herd for quite a while now. It's MUCH easier to compile old electronics than it is to get rid of it! LOL

[dieseljeep]

Originally Posted by Tubejunke

I have a large Variac that I as of yet have found no way to use. Not anyting wrong; it just has oddball input and output sockets which I have no plugs for. This thing is pretty much top of the line for its time and I would like to use it, but I would sell if you are interested. Been trying to thin the herd for quite a while now. It's MUCH easier to compile old electronics than it is to get rid of it! LOL

A Variac is a auto-thansformer, not an isolation transformer.

[Tubejunke]

Originally Posted by dieseljeep

A Variac is a auto-thansformer, not an isolation transformer.

Ok; the problem with assumptions right? Anyway, I have a Variac. I assumed it was isolation simply due to its heavy weight which told me that there was a transformer present and I thought that an isolation transformer was a 1 to 1 ratio transformer used to simply isolate the user of equipment plugged into the unit from direct contact with line voltage/current.

Correct me on this one.

[old_tv_nut]

Originally Posted by Tubejunke

Ok; the problem with assumptions right? Anyway, I have a Variac. I assumed it was isolation simply due to its heavy weight which told me that there was a transformer present and I thought that an isolation transformer was a 1 to 1 ratio transformer used to simply isolate the user of equipment plugged into the unit from direct contact with line voltage/current.

Correct me on this one.

Both an autotransformer (secondary connected to primary and not isolated) and an isolation transformer (secondary not connected to primary) have iron and magnetic coupling. So, heaviness is no indication one way or the other.

If you connect an ohmmeter from primary to secondary, an isolation transformer will show infinite ohms. An auto transformer will show conduction indicating a connection.