I thought that all was said and done about this project, but then the tubes came and the choice of the different frequency (18KHz) creates new questions, until I receive that Rb frequency standard.

I just realised that I could simply find an existing quartz with a multiple of the desired frequency and divide it with one 74HC4040 (I have mutliple reels of these, don't ask me why)

So what frequency is easily divided by 18000 ? 18.432MHz gives a perfect division factor of 1024. However this consumes a LOT of current (in the 10mA range).

A lower frequency could work but I don't have 9.216, 4.608, 2,304 or 1.152MHz in stock.

I have a bunch of 3.6864MHz and I built an oscillator there : https://hackaday.io/project/8121-discrete-yasep/log/26870-clock-generation-circuit I measured a 1.6mA power consumption, which is a bit too much. Given my latest experiments, can I draw less ?

The division ratio is also a little bit "odd", giving 204.8. The idea so far is to show 5 cycles on the scope, at 18000/5=3600Hz (277µs). The 4040 will divide by 3686400/3600=1024. So this design will be actually a 3600Hz generator...

For more flexibility, jumpers will select the frequency. But now the most critical aspect is to reduce the power consumption and ripple. So now is the time to create a new low-power oscillator, using all the squillz I earned with the other crystal oscillators.