[time-nuts] Changing FE-5650A frequency?

[Alexander Wright]

Hi all,
I've recently ripped some FE-5650A's out of some old equipment, but they 
seem to be a custom build, here you can see they have the option just 
listed as "-":
http://cambridge.m0tei.co.uk/files/IMG_20130330_232647.jpg

They seem to be single rail (15v) supply with an 800kHz output. I 
wonder, does anyone know if it's possible to change its frequency? As 
far as i'm aware this model doesn't have serial control.

Thanks,
Alec M0TEI