Feedback on “4AT Atherton” Story

Our feature “4AT Atherton“, on the history of that Queensland, Australia, station generated some interesting email correspondence that Al Kirton of Radio 4KZ, and Radio Heritage Foundation supporter, forwarded on to us. We think it is worth sharing.

Aubrey McKibben (VK5QD) wrote:

Claude Singleton VK4UX (’Silent Key’ September 1990) –  also worked at 4AT in the early days and I guess would have been the ’team leader’ (in todays speak) –  for the transmitter – attending work from Malanda each day.

I’ve attached a ‘newspaper clipping’ about Bob Hardinge, who along with his late father, their company being the erectors of the present 4AT mast.

Around 2005, Bob was contracted to provide a new AM mast for 3YB Warrnambool (Victoria) for ‘ACE Radio Broadcasters’.

I had wrongly assumed Bob was a ‘Southerner’ (Victorian) – and would likely never have heard of 4AT – and so began  energetically ‘describing 4AT’s history’ – but was quickly interrupted.

I just managed to let him know ‘that the mast was know within the Australian broadcasting scene as a “HARDINGE” mast’ explaining that I considered the name ‘a likely typo’ – the correct name likely being “HARDING’ – whereupon the chief engineer of ‘ACE’ – Ray Baker quipped: “meet Bob HARDINGE”!

Well; a feather could have blown me over.  In shock I listened as he explained the mast in true detail, explaining even the ‘little’ (or at least, hidden from view) – coil at the top of the mast etc.

It was a shock to meet someone who had worked in such detail in a place far, far away from Warrnambool Victoria and considering the chances of meeting that very person.

He further recollected  ‘that despite the many towers he and his late father manufactured over the years’, he remembered the 4AT tower in  particular because of the ‘hefty structural requirements the PMG laid down’ (cyclone related, no doubt)

Some basic historical facts on 4AT I’ve gleaned over the years:

Originally, 4AT was one of four radio stations in Australia owned by companies associated with the Jehovah’s Witness church.

The arrival of the Second World War saw emergency radio regulations enacted.

In the minds of the censors of the day, there ‘could be all sorts of devious ways of getting messages through to the enemy’. Loose lips, after all, could sink ships.

The Jehovah’s Witness churches pacifism, and therefore determined stance against all wars, was translated in the government mind into actually broadcasting items to hinder the war effort.  I myself heard various innuendo over my years on the Tablelands to this effect.  Like all matters in life, the varacity of such claims needs scrutiny.

On the 8th of January 1941 the Postmaster General moved in to close all the stations down.

There were various petty incidents involving announcer’s speech at 2HD and 5AU (and presumably 4AT) where – to the censors mind  – information could get passed to the enemy, had ‘he’ been listening.

Sir Ragnar Colvin (in charge of the navy) was very angry and personally would have refused to let the stations go back on the air, however it was agreed that they could return subject to the provision of managers that were not Jehovah’s Witnesses. Before this could happen, however, the government’s ‘Unlawful Associations Regulations’ were applied, and the station(s) were closed permanently.  The Jehovah’s Witnesses apparently appealed to the High Court of Australia but were unsuccessful.

The 4AT transmitter site passed to the ABC (Australian Broadcasting Commission), which has used it ever since the transmitter came back on air on January 1941 (maintained today by “BAI Australia”)

On ocassion the 4AT transmission would ‘turn up on the ’80 metre amateur band’ – all ‘distorted and garbled’.  Historically, the station was based on always running a ‘pair’ of ‘seperate’ transmitters ’through a combiner’ (two transmitters in parallel).  I was told if one transmitter failed there could be some sort of  ‘load imbalance’ which would cause a healthy 5th harmonic emitted on “3600KHz” (right where amateur chit-chat happened)


The length of the mast is interesting.

In keeping with standard knowledge regarding ‘AM mast length’ and ‘wanting to get the best field strength out of them’ the ‘bigger and better designed AM radiators’ (ABC masts) – are seldom a ’standard’ 1/4 wavelength.

All of those ‘big ABC masts’ throughout Australia are ‘even longer than a 1/2 wavelength’ and use a ’top loading’ hat (to allow ‘adjusting/maximising’ field strength ‘off-of the side of the mast’)

4AT is no different being 0.58 wavelengths or 208 degrees in ‘electrical length’.

This is just a tad longer than the ‘industry standard’ around the world of “190 degrees”.

The present mast was erected circa 1972 and ’top-loading’ was achieved with 9 ‘umbrella wires’ (top loading wires)

According to some old PMG documentation, a  “Mr Robinson” (from PMG Lines Section of South Australia) – along with a rigging crew spent considerable time (weeks in fact!) – adjusting and working out the arrangement of the top loading for the 4AT mast (can you imagine the effort if done in hot and humid weather!)

They had much trouble ‘creating a current anti-node’ (i.e. maximum current point) – as they measured along the mast (I would imagine they desired maximum current point to be at the centre of the mast) – which resulted in them ‘dropping 3 of the umbrella wires’.  So to this day there are a total of 6 ‘top loading  wires’.

I managed (with a normal camera and no filters’) to catch these wires at a good lighting time and have attached the photo.  Obviously they are not ‘guy wires’ and are there to adjust the radiation pattern and feed point impedance.

It’s amusing to note that during the 1995 refurbishment of 4AT (old STC transmitters scrapped etc) – that the main tower was “repainted only after a substantial amount of moss was removed from the tower”  !!…. certainly a comment on the location of the station in the tropical and very beautiful Atherton Tablelands, part of Australia’s wonderful ‘wet tropics’ region.

Aubrey McKibben (VK5QD)

Mike Patterson (VK4MIK) wrote:

I believe that the original station was near Yungaburra and owned by a church – possibly Lutheran.

I heard that they were concerns about it passing messages to the enemy !!

There have been some occasions when its harmonics were radiating on 3.600 Mhz and the Cairns RI OIC Jerry Millwood organized his team to attend and the problem was rectified.

Aub McKibben and Keith Searle both used to get called in to attend to issues which occasionally occurred.

Wilf Booth PMG also used to do maintenance as they had responsibility.


And finally Al Kirton commented:

A BAI tech told me a few weeks ago that the top third of the 4AT mast was taken off and the transmitter power increased from 4 to 5kW.

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