[Elecraft] Parts for compact loop antenna - toroid help

[Masleid, Michael A.]

Hi Daniel

>I'm just posting this so that someone can tell me ... NO - DON'T DO THAT - or -
>DO THIS.

OK, use FT 43 material.

You want to make a broadband transformer.

You want tight coupling, but you need the right turns ratio.

If the small loop has a radiation plus loss resistance around 1 ohm,
you need a 1:7 turn ratio to match 50 ohms.  You want the shunt reactance
of this 7 turn coil to be much more than 50 ohms.  FT 43 can do that.

If you run 8 watts, you need 20 volts on 7 turns.  An FT-50-43 core
will run about 138 gauss at 3.5 MHz to do this.  Use a bigger core to
reduce loss, handle more power, and have enough room for the windings.

73, de Michael, AB9GV