[TCML] charging reactors

[jimlux]

Ed Phillips wrote:
> 
> 
> jimlux wrote:
> 
>> Ed Phillips wrote:
>>
>>> So, if one needed to build or buy a dozen charging inductors for a 
>>> resonant charged spark gap coil, where would one look..
>>>
>>> It's for an application where there's multiple coils being charged 
>>> from a common HV DC bus.
>>>
>>> Probably need 5-10 H, and it needs to handle a few hundred mA to amp 
>>> (e.g. 10kW @ 10kV is an amp), and, of course, have a 10-20kV voltage 
>>> rating.
>>>
>>> --------------------------------------------------
>>>
>>>    That's a mighty big assignment!  Those things will be expensive if 
>>> you can find them at all.................
>>>
>>
>> Well.. I've seen some websites with TCs where folks wound several 
>> hundred turns of wire on a Ferrite U core of some sort or another. I 
>> suppose one could find the bare cores for MOT's for instance. (or a 
>> cheap source for the transformers new, and just saw off the windings 
>> you don't need..)
>>
>> Just casting about for ideas..  And expensive is a relative term.... 
>> $50 each wouldn't be unreasonable.
> 
>    I hate to be negative but you're talking about really serious chokes 
> here and nothing you can do with "several hundred turns on a U core".  
> You want a lot of inductance with a lot of DC flowing through the coil 
> and that's something you're not going to get by casual experimentation.  
> I would guess you'd need a high-quality transformer iron core with cross 
> section of at least 4 square inches, a fairly large air gap, and lots of 
> wire with special attention to insulation.  You can probably find power 
> inductor design information on the web if you hunt around.  If you can 
> find something meeting your qualifications for $50 that would be a super 
> bargain!  I'm looking at a 1958 Stancor catalog and see that a 6 henry, 
> 500 ma choke has a base size of 5-5/8" x 5-1/2" and is 8-1/8" high.  
> Shipping weight is 24 pounds and list price 50 years ago was $54.00.  A 
> 10 henry, 1 amp choke from UTC is 4-3/4" x 6-7/8" x 10-1/2" and weighs 
> 40 pounds.  Net price was $40 half a century ago!  Neither of these 
> transformers is designed for high pulse voltage across the windings and 
> that would of necessity require more insulation with more iron and more 
> copper.
> 

I was expecting physically large and heavy.. And at least you've given 
me some ballpark numbers..