[Amps] HV PS transformer

[Radio WC6W]

Hi Paul,
   I conjured up a simple solution for winding that style of transformer a while back.  

   "Standard" Teflon isulated wire is typically rated for 600 volts.  The 3KV rated stuff is too thick.

    Instead, run two #22 teflon insulated wires through some #12 teflon tubing.  Then, parallel as many of these assemblies as necessary for the required secondary voltage and feed them all through tubular copper braid which will become the primary.  A piece of woven fiberglass tubing, typically used in under the hood automotive wiring, over the outside completes the assembly.

  This single cable is then wound around the core(s).

  I connect the pair of wires from each teflon tube in series; then to individual 1KV fast diode bridges.

  These bridges are then connected together to create the output voltage.

  With 380 volts on the primary, 8 secondary runs (4 tubes) are good for 3KV. 

  The only disadvantage of this scheme is that all the extra insulation does need more core window area than would typically be required.  

  Incidently, that '91 QEX article is overly heavy on the core side.  A few more primary turns will greatly reduce the core cross section requirement.   At these frequencies and power levels, almost any core of the correct material and large enough to accomodate the windings will be adequate.   

73 & Good afternoon,
   Marv WC6W 

http://wc6w.50webs.com/ 




--- On Wed, 3/11/09, Paul Decker <kg7hf at comcast.net> wrote:

> From: Paul Decker <kg7hf at comcast.net>
> Subject: [Amps] HV PS transformer
> To: amps at contesting.com
> Date: Wednesday, March 11, 2009, 9:02 AM
> GM gents, 
> 
> 
> Part of my (3cx800A7) amplifier project is to do something
> "new".   Well OK, it's old, but new to me. 
> 
> 
> 
> I'm trying to reproduce the switch mode power supply
> outlined by Tim Hullick W9QQ (SK) in Feb 1991 QEX.  
> Things are fairly strait forward, but I'll throw a
> question to the list. 
> 
> 
> 
> In the article Tim says:   "...The secondary winding
> consists of as many turns as required, looping through the
> pipes to provide the necessary secondary voltage.  For any
> high secondary voltage, Teflon (r) - insulated hookup wire
> should be used because of it's superior insulating
> properties at high voltages.   Any small gauge Teflon wire
> can be used as long as the required number of turns will not
> be too tight in the pipes.   I used standard no. 20."
> 
> 
> 
> 
> Q.  So does that mean the secondary wire needs to have a
> minimum insulation voltage rating of the secondary voltage
> i.e. greater than 2200V? 
> 
> 
> 
> I have found Teflon coated wire with that high of
> insulation ration, however I have doubts he could get 50 or
> so turns through a 3/8 id pipe. 
> 
> 
> 
> Q.  Any ideas on what Tim might have been getting at and
> what suggestions for wire and sources? 
> 
> 
> 
> BTW, parts placement is going along, what a chore to get
> everything to fit! 
> 
> 
> 
> Thanks and 73, 
> 
> Paul kg7hf 
> 
> 
> 
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