70 years-old QRM

[k4kyv]

I just happened to tune in one of the local university FM stations this afternoon, and heard a re-broadcast of a 1936 Woody Herman concert.  What fascinated me the most was that you could hear a cacophony of weak stations in the background, typical of the AM band at night when the local signal is not full quieting.  Occasionally I could actually make out a word or two from the background QRM. And this was QRM that occurred 72 years ago.  Other than the program content, it didn't sound much different from what you hear on the AM band to-day.

The recording had to have been by mechanical disc, recorded off the air, using a good quality receiver.  There were no tape machines back then, and an old transcription disc wouldn't have had the AM background interference.  You could also hear pops and scratches in the original music source, which was evidently on transcription disc.

I was amazed at the quality of the audio.  Other than the background noise and occasional record scratches, the music was entertainment quality even by to-day's standards, particularly for the AM broadcast band.  No tin-can audio, fuzziness or muffled highs.  Yes, the frequency response was limited and the recording was not exactly CD quality, but it was still good enough for broadcast even to-day.