I visited 4BH AM when training for my Broadcasting Certificate at AWA . It was an AWA 2KW transmitter of ~ WWII or earlier vintage with high level modulation meaning it had a 2KW audio Amp driving the modulation transformer. So I guess they did have high powered audio Amps in the 1930s! Broadcast spec meant distortion must be below 3%. Their transmitter was on the tidal salt flats at the delta of the River for good ground-plane conduction. Popular 4BH DJ in the 1960s was Bill Gates (Top 40)- same name as Gates mixing console! Popular 1970s DJ at 4QR (50KW) was Bill Hurrey (Jazz Fusion/Disco). First Bris FM was 4ZZZ, later engineer, an AWA friend, obtained Channel 9's 1950s RCA BC-6 mixing console from them, gutting it and converting it to solid state, a shame as it is a very collectable piece these days. First commercial FM 4MMM used 1970s RCA transmitter (excellent fidelity) on Channel 7 tower; they used Shure MM cartridges with backcueing stylus and Cuemaster (Melbourne) spot cart players. 4BH used Euphonics straingauge cartridges and 4QR used early square Ortofon movingcoil cartridge - very collectable & expensive today!

A majority of commercial AM stations even today only have an output of around 2kW. Transmitter towers are most often on huge flat areas which allow the signals to travel where they are most useful and this is where AM has a distinct advantage with range. Commercial stations in the capital cities are mostly 5kW. As for the ABC, many of their AM and FM transmitters far exceed the output of their commercial competitors and 50kW is not uncommon and for their FM stations the output can be up to 250kW. FM transmitters are usually at the top of a nearby mountain or on shared space on a TV tower.

Here in Sydney, where there's around half a dozen underground tollways (with at least two more coming) each tunnel has transmitters that repeat all radio signals as well as providing mobile phone coverage. With this you can hear your radio station undisturbed for the whole length of the tunnel and the tunnel operators can broadcast warning messages to everyone who has their radio on too.

Popular 4BH DJ in the 1960s was Bill Gates (Top 40)

Trivia: I think was the guy who discovered and promoted the BeeGees before their voices broke!

Maven

^ Their voices broke?

I guess that was an off the cuff remark toward their high pitched voices when singing songs such as Staying Alive and More than a Woman.

I'm a Bee Gees fan but I always wondered about their voices in those songs. Leo Sayer was similar with You Make Me Feel Like Dancing.

No, really - the Gibb brothers were performing under Bill Gates' sponsorship on air and around Brisbane before they reached the age of puberty, when their voices were naturally in the high register - the falsetto style was something they adopted much later when working in New York, copying from white singers like Frankie Valli and black soul groups like the Stylistics.

Maven