Thanks,
The unit that I have does not have the optional input jack for an external reference. That said, I do already have plans to add that capability to the frequency counter so I can use the Rubidium while the unit is in the shop.
But mainly, I would like be able to use this counter in the field or to perhaps loan it to a friend. So it won't always have a Rubidium handy.
I did actually order an OCXO off eBay last week thinking I could add that since there is a connector and switch inside the unit that facilitates using an internally mounted TCXO or OCXO. Should be straightforward to fab a matching interface to connect the OCXO to the unit.
In the meanwhile, I would like to get the unit on frequency for fun. More of an intellectual exercise than anything else. Currently the unit does tune from ~10,000,045 Hz to 10,000,250 Hz, but I didn't do any testing of how stable the frequency was when set.
So, I guess I'll swap out the fixed capacitor and see if I can move the frequency down a bit. Straightforward and easy to revert if it doesn't work.
Thanks again