Re: wierd MOT's

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Laurence Davis by way of Terry Fritz <twftesla-at-qwest-dot-net>" <meknar-at-hotmail-dot-com>

I ran into something like what you are describing.  i wanted to
test my 12kv/30ma nst with my meter without a hv probe. so, i thought like 
you did... drop the voltage rather low and measure the output.
however i received the same results that you did, unusually low output on 
the secondary. i also tried using a AA battery and touching the primary 
leads quickly. same results, lower expected voltage.

FIRST... dont do that again, go buy a hv probe. analog meters are more 
durable than digital, but if you go over the voltage range you'll toast any 
meter.

second... i suspect that the primary is designed to operate within a 
specific voltage range. 12v is way below that im assuming. thus the field 
strength of the primary wasn't strong enough to drive the secondary 
efficiently. once you hit 60v, the voltage on the secondary likely 'took 
off' and blew your meter.

how about running the xfmr in reverse? 120vac to secondary, measure voltage 
on primary? would the windings handle it? hmmm...

standard meter -- 10 meg ohm impedance.
120vac into secondary - (assuming mot has 2.4kv out, ratio is 20:1)
120/20=6vac.  Apri=120/10^6 =12ua. Asec=12ua*20=240ua.
secondary should handle at least 500ma-1000ma.

this should work. am i correct?
larry d.

>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: wierd MOT's
>Date: Thu, 25 Jul 2002 07:33:37 -0600
>
>Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><m.j.watts-at-massey.ac.nz>
>
>Hi Mark,
>
>On 24 Jul 2002, at 20:14, Tesla list wrote:
>
> > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><A123X-at-aol-dot-com>
> >
> > Having finally completed my power control box I decided to try measuring 
>the
> > voltages of my MOT's by putting only 12v into the primary and measuring 
>the
> > secondary. The results I got were 90v output which suggests the MOT only 
>has
> > an output of 900v. I decided to raise the variac up and the output
>voltage of
> > the MOT continued to fit the same pattern. Then a little past 60v my
> > multimeter began making a wierd noise and not working right. Now under 
>the
> > same pattern as before the output should have only been about 500v which 
>is
> > well below the 750vac the multimeter should be able to read. Can anyone 
>why
> > my multimeter broke and my MOT appearently only puts out 900v?
> >
> > Mark
>
>Is the transformer *known* to be good?
>
>Regards,
>malcolm
>
>
>