Radios that only receive one station I guess would fall into two categories: Early P.O. licenced, and (rarer) Promotional. The one I came across (in picture) receives only station indicated on mock velocity microphone.

The other type would be early GPO? or PMG? licenced radios which people could Hack to get other stations (such as - in UK - European stations or Pirate stations?)

The early days of radio in Australia involved the 'sealed set' scheme. One radio = one licence = one station. It was doomed to fail though as people wanted choice and because it was easy enough for many to build pirate radios with a variable tuning mechanism and just keep it hidden from the inspectors it was just too hard for the government to manage.

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A valve a day keeps the transistor away...

A bit like prohibition.

Some of the 'sealed sets' even had a normal tuning capacitor set to the licenced station. It just wasn't accessible from outside.

An original 'Sealed Set' would be quite collectable today, I imagine, if found!

Any that still exist would have most likely been broken into and modified when the laws were changed. If one were still to exist in original form, yes it'd be worth having I reckon.

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A valve a day keeps the transistor away...

QUOTE: it was just too hard for the government to manage.

The American government didn't want to go there. Also, trying to tax receivers and then distribute the proceeds to radio stations would imply that stations better not annoy the government else the government might "forget" to pay them... That 1st Amendment thing (our freedom of speech rights).
So radio stations run commercials after they provide programming designed to attract as many ears as possible. One famous DJ Dan Ingram in New York City mentioned "WABC, the station that loves you, because your ears are a saleable commodity"

After the sealed set scheme the radio stations, which would later affiliate and in some cases be networked, were divided into A-class and B-class stations. A-class stations could only continue to rely on licence revenue but B-class stations surrendered their licence revenue for the right to advertise.

Later down the track the Commonwealth Government bought out all the A-class stations and this became the Australian Broadcasting Commission. The ABC still doesn't run advertising and relies on government revenue to operate.

The American government didn't want to go there.

I can't say I blame them. The ABC runs a four-channel television network, at least two FM networks, at least three AM networks and at least one digital-only network. Personally I think that is a bit much for the taxpayer in these times but that's a story for another day. It was great when we had a population of five million and someone had to come up with the capital to build all this in the 6th largest country in the world but the tyranny of distance isn't an issue these days.

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A valve a day keeps the transistor away...

A sealed set would require a 'trimmer' knob to compensate for drift.

I went back to guy's place today who had that single-station Promotional radio on display to get a better picture (was short on time 1st visit and only had cheap phone to take picture) -- found it was older than suspected (had thought it might be transistor). As you'll see from picture looking at the back, it is definitely earlier than transistor and does in fact have a Trimmer knob that I thought would be necessary!

The base contains a permanent magnet 1950s style loudspeaker facing upwards.

Brad said the following:-

"The American government didn't want to go there."

Actually the US federal government did fund public broadcasting such as NPR (radio) and PBS (television) which is pretty much the equivalent of our ABC and SBS here.

In president Trumps first budget, he has stopped all funding to all forms of public broadcasting in the US in order to fund the US war machine and it could give our own government the means to do likewise with the ABC (The unofficial organ of the Australian Labor Party which poses as a public broadcaster) and SBS in order to reign in our budget.

Who remembers the old Trades and Labor Council owned radio stations in Australia in all the capitol cities with the "K" prefix in the call-sign like 2KY in Sydney, 3KZ in Melbourne, 4KQ in Brisbane, 5KA in Adelaide and 6KY in Perth.

I didn't say that, I was quoting.

I think you are on the money regarding the ABC though. One day we may well work out what their motivation for bias is.

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A valve a day keeps the transistor away...

Wasn't the ABC under it's original charter to be free of "Political Bias" and when did that get scrapped and got infiltrated by the ALP and the Greens?

I'd like to think that it all changed when we had Rudd, Gillard, Rudd, but I think I can go back further then that to the mid 70's when the all powerful union within the ABC (the Staff Association) was calling the shots and would go out on strike at the drop of a hat and that pretty much happened after the dismissal of the ALP government under Gough Whitlam in 1975.

Strike action at the ABC would be the best thing for the network at the moment I reckon.

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A valve a day keeps the transistor away...

But who would notice lol.