[Amps] MW Oven Transformer question

Will Matney craxd1 at verizon.net
Tue Mar 21 14:30:00 EST 2006


Gerald,

My guess by seriesing two will drop the flux density in each to around 10 kilogauss as each will have 1/2 the line voltage across it. That's well below the bottom of the knee and in the linear region. It will raise the power capability X2 also, but I can't say how much without knowing the core dimensions. Two this way though will run as good or better than a lot of off the shelf linear transformers because of the low flux density. This means the efficiency is really high, probably 95% for a rough guess.

Best,

Will


*********** REPLY SEPARATOR  ***********

On 3/21/06 at 2:22 PM TexasRF at aol.com wrote:

>Thanks Will and John; I now have an understanding of the heating issues 
>with 
>the MOT. It appears that these transformers are really a poor choice for  
>continuous operation such as a filament power source. Two transformers
>with the  
>primary and secondary windings series connected will work and for  testing
>the 
>traveling wave tubes is the quick method to be used.
> 
>Many thanks for your help in my continuing education!
> 
>73,
>Gerald K5GW
> 
> 
> 
>In a message dated 3/21/2006 11:10:15 A.M. Central Standard Time,  
>craxd1 at verizon.net writes:
>
>If you  want to add turns to the primary (if there's enough room, and
>should 
>be with  the secondary removed), you can do a simple test to see how many 
>turns to add.  First, use the formulas I published last week about
>figuring the 
>core size and  number of turns to find the correct number of turns for the
>core 
>size you  have. Next, connect the primary to 120 Vac and wind a 10 turn
>coil 
>secondary.  Take that secondary voltage and divide it by the 10 turns.
>That 
>will be the  turns per volt. Last, wind the extra turns you've found you
>need by 
>the  formulas and the known turns per volt. One good thing on this
>transformer 
>in  question, the primary is on the inside. If on the outside, you'd be 
>screwed on  removing the secondary.
>
>Best,
>
>Will
>
>*********** REPLY  SEPARATOR  ***********
>
>On 3/21/06 at 11:42 AM John Popelish  wrote:
>
>>TexasRF at aol.com wrote:
>>
>>> Not what I hoped  to hear but I appreciate the good info! 
>>
>>If you have a supply  of this kind of landfill, you might put two 
>>similar units side by  side, wire the primaries in series (effectively 
>>halving the volts per  turn, so eliminating the saturation problems). 
>>Then you can knock the  shunts out and wind a similar secondary on each 
>>(doubling the number  of turns to compensate for the half primary 
>>voltage) and wire those  two secondaries in parallel.  This gives you a 
>>reasonably  efficient transformer (that won't overheat without a fan) 
>>with about a  kVA rating.
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>
>
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