Need help from Antenna gurus!

[dwilson]

Purchased an old Advanced VOR antenna and lead from this group and I am confused by the antenna lead.

The radio end of the lead is a standard coax that needs to be stripped and have a BNC connector added.

The antenna end has me stymied. It looks like the center conductor and its insulation was stripped from the braid and bent back along the shaft of the lead then additional braid was added around the bent back core all the way back to the bend. Everything was then covered with heat shrink insulation.

(I deduced the config through the heat shrink by taking it into the X-ray department and looking under fluoroscopy)

There are two ring type screw on connectors that get attached to the antenna at its central point. (Cat Whiskers type VOR antenna.)

Both of the rings are crimped to braid, and nothing is crimped to the center core conductor.

Continuity testing reveals that the two antenna attach rings are connected together through the braid.

I don't understand how the radio can receive anything when the center conductor is not attached to the antenna. Some sort of inductance?

Thanks

[Mel]

The VOR antenna uses "inductive" coupling to the lead.

[aerhed]

Yes that is correct. It is a "Balun". I've made several of them. The internal cat whiskers in my Emeraude (welding rod) will pick up a VOR from like 80 miles.

[dwilson]

Love this forum!

Thanks for the quick answers.

[az_gila]

This is probably what you have - from AeroElectric Bob -



http://www.aeroelectric.com/articles...brication.html

[dwilson]

That looks like it!

Still scratching my head as to how it can work.

[krw5927]

And from everybody's favorite "bible", AC43.13, although this does appear to differ from 'lectric Bob's diagram....