As someone mentioned, my Aussie radios, here in NJ, are far from their home.



But I figured I'd give them a treat by feeding them an AM modulated Aussie radio station Internet stream. What I used for a modulator was an old hobby grade tube RF signal generator with the ability to have modulated audio tones. Removed the tone generator circuits, and changed them into an audio amp (6AQ6, 6AV6 also works), cathode follower (6C4) and some geranium detector diodes to act as an AM detector to provide detected audio to feedback to the audio amp. I kept the old RF modulator and oscillator (12AT7) circuit, which has 6 bands.

The feedback loop makes a big difference.
This below is a similar circuit, and shows the feedback loop:


The fact that Aussie radios usually have an antenna input wire or connection makes it easier to feed my modulator to the radio, with less outside signals to interfere.

The actual circuit (don't know if videokarma will let me link it)

If that doesn't work, try http://videokarma.org/showthread.php?p=3083347#post3083347

I'm sure your Aussie radios will enjoy their treat. It could, however, make them a little homesick!!

Someone over in Videokarma pointed out that modulating the oscillator would produce some FM as well as the desired AM, so I reworked the circuit, using a 6CS6 pentagrid tube (a sharp cutoff version of the 6BE6) as the AM modulator, isolating the RF oscillator.

A nice collection of radios which now will be homesick with the Australian music and programs.

A well known and sadly deceased radio collector in Bathurst had a similar setup with a low power transmitter.

Although think he played records or tapes.

You should play a trick on some mates by relaying the Australian programming through them when they visit.

I've often spun the yarn that old radios always play old music - my justification for listening to 2CH when most of my staff listen to teeniebopper music on 2JJJ and the like.

You could spin the yarn that these are Australian radios and can only pick up Australian stations.

Shout them a few beers first though...

Here's a well programmed station that finds some rare 50's tracks:
87.6 Vintage FM (Penrith NSW)
They had issues with excessive added reverb which they have since corrected.

If any circuit needed a modern counterpart it's this one.
Fortunately, it appears Google gives good results.
Don't get me wrong, I'd love to see this one working too

Consider someone's first experience with a vintage radio
when you guys are not here to ask questions.
The radio already requires you to extend yourself much more
than I considered, and I would say that I'm not too shabby
with electronics.

A low powered AM transmitter might become a requirement,
though I think anyone in a rural area on the edge of the digital
cliff would be kicking up a storm if it happened.

"I think anyone in a rural area on the edge of the digital
cliff would be kicking up a storm if it happened"

Hopefully the inability of digital radio to cover large areas will save AM radio. Hopefully more than ABC Local Radio, used presently for providing disaster information such as with the New South Wales bush-fires, will survive.

A disadvantage of DAB+ for emergencies is that these receivers draw a much higher current than AM & FM receivers and so are much harder on batteries.

That is some good news I guess, and I do agree.

I didn't expect the powers that be would get away with it
as easily as television and mobile phones.

Of course the DAC, PLL, and whatever other digital stuff
has to do the same work at high clock speed when the
amplifier is run at low volume... I didn't think of that.

It'll be a while before AM and FM go. Digital radio doesn't exist outside the capital cities and only one or two carmakers fit their vehicles with digital radios.

Digital transmissions also lack the punch of analogue transmissions. When I go on camping trips to various Central West locations I can listen to either 2GB or 2CH all the way to Mt Victoria but by then there is no digital signals from Sydney at all.

The possibility of the loss of medium wave stations has led me to think that I need a shortwave antenna so that at least those transmissions were receivable.

I have the room for one of those dipole antennas with three different lengths of wire for each arm. A coaxial feed is needed because of all the digital hash around the place. Currently looking at the baluns needed and how to make them.