I'm wanting to build this active antenna, but can't find the core to
wind the output coupling transformer.

http://www.elecdesign.com/Articles/I...ArticleID=6244

This is the authors description of the transformer.

"The toroidal transformer’s primary is 36 turns of No.24 enameled wire
wound on a core from a Sony 1-421-302 line choke. Its secondary is
nine turns of No.24 telephone wire."

And this is his decsription of the performance of the amplifier.

The frequency response at low gain is very flat (±0.2 dB) from 200 kHz
to 35 MHz, and is only 0.4 dB down at 60 MHz. At standard high gain,
the response is very flat to 25 MHz and -3 dB at 50 MHz. The maximum
output level in all gain configurations is over 500 mV rms into a
75ohm load.

Does anyone have any idea what type of core that would work as well?

Thanks
Mike