Why star ground????

[Voicecoil]

There is no such thing as an earth at radio frequencies.
Kit

Well I was taught that this is not quite true, but only if it is a plane (which could be the walls of an enclosure as long as they're conductive and conductively bonded across any joints etc.) - as soon as you give it length >> width (i.e. a piece of wire) it has inductance and everything goes to rat shit, and smelly piles of it.

[Kitwn]

Well I was taught that this is not quite true, but only if it is a plane (which could be the walls of an enclosure as long as they're conductive and conductively bonded across any joints etc.) - as soon as you give it length >> width (i.e. a piece of wire) it has inductance and everything goes to rat shit, and smelly piles of it.

Absolutely true, but you have to take great care.

When I was a shiny new trainee at the BBC Transmitter Dept. back in the early 80s there were two demos that brought home the point I was wanting to make...

In the antenna fields of Daventry shortwave radio station the open wire feeders were supported on insulators hung about 3m up from tubular steel posts about 200mm in diameter which were firmly concreted into the ground. If you held a coin and ran it down the post under a live feeder you could clearly see sparks between the coin and the post.

At the Droitwich station there was a large neon bulb connected between the outer ground of a medium wave feeder where it left the building and the station earth strap which ran all round the inside of the building. It glowed a lovely neon pink and flickered in time to the music.

Happy days!