solarwind wrote:
> I am referring to the image here:
> http://sci-toys.com/scitoys/scitoys/radio/xmitter_schematic.gif

Ick. If that TTL oscillator survives having +9V across it, I'll be VERY 
surprised...

> I understand that the top left pin of the crystal oscillator is the
> input for some voltage. So assuming that I provide a steady +5 volts
> on that pin, what will I see on the output pin (top right)? Will I see
> a 1 MHz wave with a peak voltage of +5 volts? Or will it have an RMS
> voltage of 5 volts?

A square wave with peaks of 5V and 0V.

Hardly ideal for radio -- it'll work, but you'll get odd harmonics going 
right the way up into the GHz range (depending on the oscillator in 
question). What you ideally want is a sine wave -- a pure tone -- 
modulated with your signal.

The circuit as presented is going to use the transformer to vary the 
voltage seen by the TTL osc., essentially making a crude AM modulator. 
Emphasis on the word "crude". There's a single-transistor AM TX in one 
of the Forrest Mims books -- it isn't perfect, but at least it generates 
something reasonably close to a sine wave.

> What governs the output power of the radio wave? 

AIUI, the "resistance" (more accurately, impedance) of the antenna is 
fixed (matched/tuned) to around 50 Ohms. Put more voltage in, get more 
power out.

> I'm really trying to learn this stuff, and I have searched in several
> books and on the Internet, but it is proving to be a difficult task to
> find this information.

Join the club...

You might get some benefit out of joining a local amateur radio society 
and doing one of the many ham radio courses. In the UK you have three 
licence classes:
   - Foundation
   - Intermediate
   - Advanced

Essentially, Foundation teaches you enough to be able to switch on a ham 
radio transceiver and use it properly, and some of the theory. 
Intermediate expands on this by teaching more of the theory, and covers 
some information that's likely to be of use if you're building TX/RX 
gear from scratch (i.e. not from a kit). Advanced then expands this 
further by teaching some microwave and UHF transmission theory (IIRC).

You might want to look up your country's equivalent of this. If you're 
serious about this, get in touch with a local ham radio group and ask. 
Most of them are more than willing to help explain the theory and 
practice behind radio technology.

-- 
Phil.
piclist@philpem.me.uk
http://www.philpem.me.uk/
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