How we measured frequency - Inside an old crystal calibrator

Continuing on our old test equipment series, today I describe an old crystal calibrator. This was used to ensure that receivers with free-running oscillators and analogue dials were on frequency. The calibrator was calibrated using WWV / WWVH on 5, 10 or 15 MHz as a frequency reference. PS: If you liked this video please consider supporting Amateur Radio VK3YE by: Subscribing on YouTube, Checking my books page at https://books.vk3ye.com Shopping on Amazon via: https://amzn.to/3iiDQXv, or Shopping on eBay via: https://ebay.us/i9DuWP (then if you buy something I'll get a small commission at no cost to you)