I have obtained a kit for an AM transmitter - two valve, basically battery operated, though I have a mains power pack coming with a 90v DC power supply. In my searching for an AM transmitter, I came across these web sites:

http://www.radiosystems.com/lowpower.html and http://www.talkinghouse.com/.

Are these permitted to be used in Australia? I doubt the one capable of pumping out 10W RF would be, but perhaps the 100mW Talking House one could be? Or would they all be intercepted by Customs and Border Protection, and they would hit me up for a licence/import fee?

You won't get keelhauled for importing the bits but in the case of the 10 watt transmitter you'd want to make sure there's a fair bit of distance between you and the ACMA. There's a huge fine for operating unlicenced transmitting gear and 10 watts would let you broadcast to half an average suburb.

I think the fine is something like $17,500.00.

There is some further reading here, though this only applies to fully assembled equipment.

There is no GST payable on items purchased for less than $1,000.00. I am unsure about import tariffs though I have never paid a tariff for a direct import and would assume that tariffs would only be levied on wholesale imports.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

I have a web page here that describes a few low power AM transmitters you could build.

Here in the USA vintage radio hobbyists have spoken well of SSTRAN transmitters, their web page, no affiliation to me.

$17500? That's about the same fine our Funny Cookie Corporation here in the USA charges pirates.

I bought the Spitfire AM Transmitter, it came through no worries, it's output is 100mW, which is part 15 Compliant of the FCC Rules, Unfortunately for Australia, the maximum output power allowed is just 10 MICRO Watts, on both Am & FM, But in New Zealand, the maximum transmitting power is 1 Watt, which is more generous, but you Must broadcast a station ID containing name and location every Hour if run for long periods of time!, (in case Emergency services or Commercial Radio gets interfered).

Thanks for the advice folks. Luckily I hadn't placed an order to buy the equipment. Given some of the tedious crap that emanates from AM stations, I'm sure I could do better broadcasting my music collection to the neighbourhood via a low power AM transmitter, but sadly, that is now not to be.

Doug, what are you using the transmitter for, is it just to transmit to your AM valve radios.
If so, in Radio Waves 2010: A solid state AM Mini Transmitter (Part 1 - January, Part 2 - April) works fine.
My Dad's is packed away at the moment otherwise I could show you. It is a nice compact simple kit to build.
The receipt I have here shows my Dad bought it from HRSA Valve Bank. Complete kit with PCB was $25, then you need case etc. Look in the above copy of Radio Waves 2010, you can get copies from HRSA.

What about this article and project
AM Transmitter

A few of us on here have bought this two valve transmitter kit from the UK:

http://www.6v6.co.uk/cp/Scripts/prodView.asp?idproduct=304.

There is an optional power supply available if you don't want to use batteries.

I will be coupling mine with an MP3-enabled CD player.

That's the one I bought. It's not gutsy but it is stable. I've used it a few times when the programming on the radio has been wanting. I just plug the laptop into it.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

One should realise,: If you have a signal generator for alignment, some of these will accept an external audio source.

You may have to do some tweaking of the modulation level and get stereo back to mono. But......

Apart from that a dual gate FET (buffer amp) fed a seperate exciter into one gate & the audio into the other, makes a reasonable modulator.

The exciter can be crystal locked.

Marc

"I bought the Spitfire AM Transmitter, it came through no worries, it's output is 100mW, which is part 15 Compliant of the FCC Rules, Unfortunately for Australia, the maximum output power allowed is just 10 MICRO Watts, on both Am & FM,"

If you set your transmitter to an empty frequency (empty meaning no local station signals, which you'd do anyway), have a short antenna (like a few meters long) located right near the radios you want to listen to it on (thus meaning you don't need much power), and most importantly, only have the transmitter powered on only when you want to listen to it, and turn it off all other times, I doubt that anyone else would ever notice it. Or even if they did, bother to rat you out to your FCC.

Brad: That's the one I bought. It's not gutsy but it is stable.

I'm not after too much power; just around the house.

Are you powering yours from batteries or mains? What are you using for an antenna?

I just use Duracells for the A cell and B battery. If I wanted some more life I'd go the Energiser lithiums for the B battery.

Aerial wire is about 5 metres long and is bluetacked to the ceiling for maximum radiation possible.

It will transmit to a radio in the next room which is fine. A picture of the beast is below.

One slight design fault, on my part, is that the sockets are too close to the A cell, though I have got around this by not using plugs and simply soldering the wires to the core of the sockets as appropriate, except for the common wire from the audio input of course, which connects with a small crocodile clip.

Timber is a scrap of Tasmanian Oak coated with white shellac. All miscellaneous hardware is from Jaycar.

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

^ Neat job.

I bought the mains power pack and I'm intending to build it all into a cube shaped box containing an Alpine brand car CD player that I have which is a pre-amp only model. I'm thinking if using an extensible car aerial, too -- which may not be a very efficient radiator, but then I don't want to broadcast to the neighbourhood either.

"One slight design fault is that the sockets are too close to the A cell, though I have got around this by not using plugs and simply soldering the wires to the core of the sockets as appropriate, except for the common wire from the audio input of course, which connects with a small crocodile clip."

The board looks to be square (and hopefully the mounting holes form a square pattern), so if you rotate the board by 89 degrees, you can have better access to the connectors.

It does look great.