I am in search of commercially available impedance matching transfer with following characteristics:
1. Input Impedance = 50 ohm, Output Impedance =25 ohm
2. Operating Frequency Range: 400 -450 KHz
3. Signal type : Pulsed CW/Linear or Hyperbolic Frequency Modulated
4. Power Handling Capacity: 5KW in pulsed mode with duty cycle less than 3%
5. Maximum Pulse Length =5ms
That really sounds like a custom made transformer. I don't have even a remote idea of an application for of-the-shelf transformers with a similar specification.
A simple search of Google and Amazon weights FvM's comments. Looks like you need to assemble the parts on your own. Quotation from bamblog website:
It's the question I'm asked most often about broadband loop antennas such as the Delta, Flag, and SuperLoop; "Where can I find the matching transformer?" Unfortunately the type of transformer required for this antenna is typically not available as a mass-produced complete assembly from commercial retailers.