Re: Help w/ Chokes

To: tesla-at-pupman-dot-com
Subject: Re: Help w/ Chokes
From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
Date: Wed, 29 May 1996 13:16:46 -0500
>>From JParisse-at-DDLabs-dot-comTue May 28 21:44:25 1996
>Date: Tue, 28 May 1996 10:42:51 -0700
>From: "Jeff W. Parisse" <JParisse-at-DDLabs-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Help w/ Chokes

>I'm in the process of constructing a 3.6kw power supply for low power 
>testing and tuning. The step-up transformers are 4500V -at- .4A plate 
>transformers from electrostatic copiers and I'm running the secondaries 
>in series for 9kV. This arrangement will power a 12.75 dia. secondary 
>coil tuned to ~100kHz. I know there has been a lot of discussion 
>regarding choke coils and I'm wondering if someone could guide me in 
>building a pair of appropriate chokes. I have limited space for the 
>chokes. If I use air core chokes, I can only accommodate a 2 dia. x 8 
>coil form.

>P.S. What's better for Tesla service 10kV-at-.3A or 9kV-at-.4?

>...Jeff (www.ddlabs-dot-com)

Hi Jeff,

If your transformers are internally current limited and 10kV-at-.3A or
9kV-at-.4 A is all you will get, then I'd say use the 9kV units.  You 
will get 3600 watts available versus only 3000 watts for the 10kV.  
That's a full 20% more energy available.  If your transformers are 
not magnetic shunt limited then it is a tossup, since non-shunt 
limited transformers are always good for considerably more power than 
their continuous rating when driven for short periods of time in 
Tesla service.  Let me qualify that statement.  O.K. to over current 
them, don't over voltage them (i.e. don't exceed the rated input 
winding voltage) or the secondary winding insulation, already stressed more in 
Tesla service is more likely to break down.  I destroyed a #-at-$%* dry
2 kVA insulated transformer last week by pushing the 120 volt primary to 
just 140 volts.  A flame shot out of the side like from an 
oxy-acetylene torch.  I will always prefer an oil filled transformer 
for Tesla service, especially if I plan to lean on it, and I usually 
do.  

When are you going to put more wonderful progress pictures on your
'This Old Tesla Coil' page?

Happy coiling!, rwstephens