Unusual reference oscillator frequencies in test equipment

[Scratch.HTF]

I would consider a reference/master (timebase) oscillator frequency other than a commonly used 10 MHz or a reference which 10 MHz cannot be divided or multiplied by an integer (for the following examples with a 10 MHz input: 50 MHz with a NB3N502 PLL multiplier (set to x5) for the FeelTech FY6600 arbitrary function generator, or 5 MHz with a divide-by-2 counter for the Philips PM5390 signal generator; both pieces of equipment have been modified for an external reference frequency input) to be unusual in test equipment.

Examples of an unusual reference (as per my definition) I have seen (so far) in test equipment include the following:
* Philips PM5193 function generator (8.589934592 MHz)
* Atten F2700-C frequency counter (13 MHz)
* Philips PM541x/PM551x TV pattern generator (5.034964 MHz - applicable only for models supporting NTSC and/or PAL-M (both 525 lines); 625 line PAL and SECAM uses a 5 MHz master oscillator)
* Kenwood SG-5110/5115 signal generator (16 MHz)

If you know of a piece of test equipment (nothing else!) which uses an unusual reference frequency as per my definition, please post it here.

[cdev]

What is the reference frequency used in the Feeltech FY3224?

[David Hess]

Integrating ADCs commonly used frequencies like 20.48 kHz, 40 kHz, 163.84 kHz, or 400 kHz to control integration time such that nulls were produced at the harmonics of the AC power line frequency.

[Scratch.HTF]

I have noted that a DDS IC (e.g. AD9851 which has a selectable internal 6X reference clock multiplier of which can handle a 5-30 MHz reference clock with the multiplier enabled; alternatively, a PLL multiplier IC set to an appropriate multiplier can additionally be used for DDS ICs which do not have an internal reference clock multiplier) and a programmed microcontroller can be used with a 10 MHz reference oscillator and a simple automatic external clock switching circuit to generate the desired reference frequency with a typical error of less than one part per billion (PPB) when programmed in the MHz range e.g. an AD9851 with a perfectly accurate 10 MHz input internally multiplied by 6 and programmed to generate 8.589934592 MHz for a Philips PM5193 results in a master clock error of 0.201 parts per billion.