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Comment by bravo22 | Hacker News Reader

439 being a prime would be an issue if you were up multiplying a lower frequency to generate it, for example using a PLL. However it is such a slow signal that it would be generated by dividing down a higher frequency. For example you can divide it down from an 18 MHz clock.

So, nope his claim doesn't make sense.

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439 from 18M requires a divisor of 41, which does sound trivial. Meanwhile 440 from 1M requires only dividing by 5 and 2 when first multiplied by 11, which might have been significantly simpler than dividing by 41.

I wonder if there is some easy way of figuring out the simplest base number-multiplier-divisor chains for getting certain numbers?

Dividing a frequency by a large prime, like 41, is somewhat difficult without digital electronics. Smaller factors are easier.

I imagine historic gearmakers for watches and clocks would have worked out such a system.

PLL's have been around since the 1920's. They could easily divide by n. The actual value of n didn't matter (within some bounds).

Would it not just have been created natively using an appropriate osciallator, given that the reference was from 1939?

A truly decent audio oscillator was only available after 1939, when Hewlett & Packard issued their first instrument.

In a 1985 letter, Dave [Packard] described Hewlett's audio oscillator as "the foundation on which Hewlett-Packard Company was able to grow into the largest manufacturer of electronic instruments in the world, the keystone that allowed four and one-half decades of major contributions to electronic measurement technology and equipment."

Maybe but it'd have been significantly more complex, here they could take a MHz piezo-electric crystal and tack on a few electronic multipliers and dividers (/1000 *11 /25) to get the desired frequency.

Quartz oscillators are usually made in at leas 10th of kHz range, for whatever reason. Second most stable oscillators are LC and would require large coils for lower frequencies.

It would still have been divided down. There aren't many "Hz" oscillators. They're all usually in KHz/MHz range.

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