"The 9kHz spacing was introduced one Sunday morning in November 1978, and 2WS was the first Sydney station to advertise its new frequency as "1224" when it started around that time. The other stations continued to use their old 'multiple of 10' frequency for advertising purposes for some years after.
AM stereo officially started in 1985 and I was one of the few to install stereo decoders in valve radios - which worked very well."

I stand corrected - I guess I only became aware of the change at the introduction of stereo AM and came to the wrong conclusion.

I bought a Pioneer KE-A433AM stereo AM car radio which worked quite well but tended to pop (literally) in and out of stereo AM regularly, even when stationary.

I also built a Playmaster (Electronics Australia) AM stereo / FM stereo tuner back then which also worked quite well - the casual listener would not be able to tell the difference between AM and FM. However it lacked sensitivity with the untuned loop antenna suggested and the best was obtained only with a tuned loop lashed up with an old tuning gang - reducing the convenience of use somewhat. It was also more sensitive to interference than commercial tuners especially when computers and switch mode supplies came in. It also picked up a hum near to my Playmaster 200 watt amplifier that commercial tuners were not subject to. Because of these problems and due finally to stereo failing in the FM it was retired.

If I remember correctly, the gurus at the time said that manual tuned and valve tuners would not be sufficiently stable in holding the tuned frequency for stereo AM and that PLL tuning was necessary - interesting to see that you proved them wrong.

QUOTE: Listening to a TRF with infinite impedance detector is a totally different experience.