Time to get your soldering iron out! I found that I had a tube of TDA7284 chips. You can get these from various Ebay sellers for <£1 each. They were originally designed for use in tape recorders, but by fiddling with a couple of values, you can make an excellent stereo limiter. The output (with the output pots at maximum) is 1V p-p. The input can vary from 10mV to 200mV and you'll get much the same output voltage. If your input signal is bigger, turn down the input presets.

The quick way to throw one together is on strip board or Veroboard - it's just 2½" X 2"!: Here's the circuit diagram:

Nice neat little circuit Mr Albert!

Looks very nice Albert, if stereo was correctly summed to mono and just one channel used, would this be a good solution for an AM transmitter if the input volume was right?

Yes! I've actually used this IC in the modulator for an AM box. The results were excellent. I just combined the channels to mono with a passive, resistive combiner, then used one side of the IC, omitting most of the components for the unused channel. I also included an additional stage, using two op-amps (in one package) as an audio lowpass filter with a fairly steep cut-off at ~6 kHz. The audio on the little (10 Watt carrier / 40 Watt peak) rig is really good. I used a TDA2030 IC as the modulator (with a big heatsink), and the RF output was a couple of IRF510s in parallel. You might have heard the rig on the air if you visited a music festival over the last few years!