[R-390] Possible source for isolation transformers?

Wed Jul 4 14:54:58 EDT 2007

Hi,

Most Variac's are not isolation transformers.  Isolation type variable
transformer are more expensive than the more common autotransformer types.

David
KC2JD/4

> -----Original Message-----
> From: r-390-bounces at mailman.qth.net
> [mailto:r-390-bounces at mailman.qth.net]On Behalf Of Patrick
> Sent: Wednesday, July 04, 2007 3:43 PM
> To: Bob Young; r-390 at mailman.qth.net
> Subject: Re: [R-390] Possible source for isolation transformers?
>
>
> 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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