[ARC5] Slightly OT: Transformers

Thu Nov 28 13:26:42 EST 2013

  Helllo Carl,
  The estimate (a graph) of VA v weight of the transformer is stuck on
  the wall at our radio club here in New South Wales (Australia).
  (That's the place to file useful info - on the wall at the radio club.
   You'd be welcome to visit, take it off the wall and copy it.)

  I've been told the graph was published in the ARRL handbook, so that's
  likely the place it came from.

  Your observations about current rating and circular mils is accurate -
  it's been in the old hand-books (ARRL handbooks) for years.
  The figure I remember is 750 cm per amp and that's 'bang' in the
  middle of the range you give.

  73 de Les Smith
  vk2bcu at operamail.com

On Fri, Nov 29, 2013, at 2:34, Geoff wrote:
> Ratings vary from 500 to 1000 circular mills per amp depending upon the 
> quality of the steel used. The 500 rating goes back to the 30's and was 
> repeated for decades in the ARRL Handbook but in WW2 and later in
> consumer 
> electronics materials improved.
> 
> There was a posting somewhere of estimating the VA of a transformer by 
> measuring the core but I cant find it right now.
> 
> Carl
> 
> ----- Original Message ----- 
> From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
> To: "Eric Mynes" <kc8wzb at gmail.com>; <ARC5 at mailman.qth.net>
> Sent: Wednesday, November 27, 2013 11:16 PM
> Subject: Re: [ARC5] Slightly OT: Transformers
> 
> 
> >  In the late 60's or 70's there was a multipage article in Electronics 
> > Magazine on power  transformers
> > and how you can determine the rating of a transformer up to kW range. The 
> > magazine is gone now
> > but perhaps there is a URL that has the PDF of those magazines.
> > 73
> > Bill wa4lav
> >
> > ________________________________________
> > From: arc5-bounces at mailman.qth.net [arc5-bounces at mailman.qth.net] on 
> > behalf of Eric Mynes [kc8wzb at gmail.com]
> > Sent: Wednesday, November 27, 2013 6:10 PM
> > To: ARC5 at mailman.qth.net
> > Subject: [ARC5] Slightly OT: Transformers
> >
> > Greetings all,
> >
> > I have some questions about transformers and this seems to be the only
> > group I'm in now that deals with tube rigs.  I hope you don't mind 
> > elmering
> > me a bit by answering a few questions.  I mention slightly off topic
> > because one day (hopefully soon) I'll start building a power supply to use
> > with my ARC 5 rigs, but for now, I just want to be able to power some 
> > basic
> > homebrew tube transmitters.
> >
> > So, my questions go along the lines of...  I have several transformers 
> > that
> > have followed me home from hamfests or someone has given me.  But most are
> > not labeled in any fashion as to what they are rated for.  As stated 
> > above,
> > I'd like to build a small power supply that can run some homebrew tube
> > rigs.  I might actually use some of the thousands of tubes that followed 
> > me
> > home from hamfests instead of leaving them piled in boxes with no use.
> > I've tried googling any number or marking on the transformers trying to
> > find a manufacturer or specifications and haven't had any luck.  How can I
> > test these safely as to not hurt myself or the transformer so that I find
> > out at least the voltages I should expect out of them?  Right now, I'm not
> > too concerned about finding how many amps they will provide as much as now
> > much voltage is on the end of the wire.  The number of amps question will
> > come soon though.
> >
> > Currently I have a transformer on my bench that has the following markings
> > 110v004h82
> > 352052
> >
> > It appears to have 3 windings.  A black set (I presume is the primary), a
> > red set with CT, and a green set with CT.
> >
> > I'm kind of skittish at just applying 110v to the black wires and seeing
> > what the others have for voltages.  So, I figure why not ask some hams 
> > that
> > might have a better clue than me.
> >
> > Please respond to me off the list as I don't want to waste too much of the
> > list's bandwidth on something that might be determined as an elementary
> > question that we all should know.  I'll be quick to say that I'm a very
> > much at an elementary stage on using HV and know enough to ask questions
> > before just trying things.
> >
> > Thank you for the bandwidth and Happy Thanksgiving to all
> >
> > 73,
> > Eric
> > k8ohz
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