About 20 mm. Conduit isn't precisely specified in diameter, I believe the ID is, but the OD can vary a little. The variable capacitance of the end sections should be able to tune out any minor variations in inductance related to a mm or so of imprecision in the former diameter.
If I was building an Ozi-pole from scratch I'd use higher-Q inductors wound with much thicker magnet wire with a larger diameter and minimal support structures. Thicker wire would be a good idea for the antenna elements too. Of course that would make the antenna heavier and more bulky, I think the original builder was trying to make it at light and portable as possible, rather than highly efficient.
2nd July 2008 11:44
Alan Yates wrote...
Jürgen,
About 20 mm. Conduit isn't precisely specified in diameter, I believe the ID is, but the OD can vary a little. The variable capacitance of the end sections should be able to tune out any minor variations in inductance related to a mm or so of imprecision in the former diameter.
If I was building an Ozi-pole from scratch I'd use higher-Q inductors wound with much thicker magnet wire with a larger diameter and minimal support structures. Thicker wire would be a good idea for the antenna elements too. Of course that would make the antenna heavier and more bulky, I think the original builder was trying to make it at light and portable as possible, rather than highly efficient.
Regards,
Alan