[R-390] Possible source for isolation transformers?

[Patrick]

I have purchased from eBay a couple of isolation transformes (CyberCare), 
apparently for use in hospitals, they are great, very well built. The tag 
says CyberCare Inc. Atlanta Georgia 30350. Also, in the 80´s I had an 
assignement in Germany and the company supplied the assignees with 220 to 
120 transformers up to 2500 Watts and a switch for 110 or 125 volts output, 
they weigh a ton, but in my workshop, which I have 220" they work great as 
isolation transformers, also I you do not have 220, they work backwards as 
well.... Wouldn´t a variac also serve as an isolation transformer?? they are 
frequently on eBay, I bought one a few years ago that was used in a teather, 
it handles 5 KW and only paid $45.00 for it, output goes from 0  to 145 
volts.

Regards....Pat.
----- Original Message ----- 
From: "Bob Young" <youngbob53 at msn.com>
To: <r-390 at mailman.qth.net>
Sent: Wednesday, July 04, 2007 10:51 AM
Subject: Re: [R-390] Possible source for isolation transformers?


> My wife is from Lima, Peru and I bought a huge 220V-110V transformer very 
> cheap there, I used it to power everything I had brought over including 2 
> bass guitar amplifiers. I think it had a capacity of 1500 watts. (lived 
> there for almost a year). I don't think it was an autotransfomer either, 
> looked (and weighed) like a traditional transformer. They are available 
> everywhere in Lima in hardware stores and other places. I would assume the 
> same is true in most other countries given the amount of Americans who 
> travel.
>
> Bob
> KB1OKL
>
>
>>From: Barry <n4buq at knology.net>
>>Reply-To: n4buq at knology.net
>>To: r-390 at mailman.qth.net
>>Subject: Re: [R-390] Possible source for isolation transformers?
>>Date: Wed, 04 Jul 2007 09:04:47 -0400
>>
>>I'm curious as just to what's under the hood.  I suppose they can get away 
>>with calling an autotransformer simply a transformer.  If it is truly a 
>>transformer, though, I can't see how they can sell them at that price.
>>
>>If they are autotransformers, is this a better solution for 220V-110V 
>>conversion than the little voltage converters available?  I belong to a 
>>list of folks who have (or will) travel overseas and several ask from time 
>>to time about what to use to power their various 120V appliances 
>>(chargers, etc.) while overseas.  While a small converter is fine for 
>>charging a battery or running a small device, I keep having to warn folks 
>>who want to power their blowdryers, etc., from them.  I thought these 
>>might be a better alternative; however, they'd certainly need the 1500W or 
>>larger unit for such applications.  I know blowdryers are available in 
>>220V models and that's probably the best way to go, but most folks aren't 
>>going to do that so I keep looking for better options.  I've explained the 
>>"best" solution is a step-down transformer, but it's unlikely anyone will 
>>want to pack one of sufficient size in their luggage.
>>
>>I know its OT, but if anyone has any thoughts on this, I'd appreciate a 
>>reply either on or off the list.
>>
>>Thanks,
>>
>>Barry - N4BUQ
>>
>>
>>  On Wed Jul  4  7:51 , "Steve Hobensack"  sent:
>>
>> >Transformers for this application are almost always autotransformers.
>>They
>> >are smaller for a given wattage because there is only one winding (with
>> >tap), and the common part of the winding can be downsized. They will not
>> >function for isolation. They can be used either for step-up or 
>> >step-down.
>> >...Steve...N8YE
>> >
>> >Knowing the leaky filters won't run on GFI circuits and are probably not
>> >all that safe when used on non-GFI or non-isloated circuits, I think
>> >some folks may be looking for isolation transformers.  While searching
>> >for voltage converters for overseas travel, I found these:
>> >
>> >http://www.eastwestintl.com/proddetail.asp\?pid=2625
>> >
>> >They state that they are transformers, not just converters, and that
>> >they can be configured to run either 110-220 or 220-110.  I wonder if
>> >these could also be wired for 120-120 and used as an isolation
>> >transformer.  If not, if someone has 220V in the shop, it might be a
>> >good way to power an R390[A].
>> >
>> >If you back up a page, they have a variety of transformers ranging from
>> >100W on up.
>> >
>> >Just thought I'd pass this along.
>> >
>> >Barry - N4BUQ
>>
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