Tektronix TDS 7XX/6XX/5XX external reference input mod?

[hvontres]

I was wondering if any has added a better frequency reference to their older Tek TDS series scopes. I have been playing around with OCXOs and my new to me HP5316a and it seems that the timebase on my 744a has a lot of jitter on it. I looked at the TDS520b schematics (thank you xdevs ) and it seems that the 1Ghz clock is derived from a 25ppm crystal. I was wondering if anyone has added an external frequency reference or even just a more stable internal reference on their scope. I was thinking having a PLL that could synch up with a 5 or 10Mhz external clock would be a great way to improve the scope.

[tchiwam]

I generate a PPS to the rear trigger on my TDS694C, that's usually pretty good to keep things in check. Since all my instruments are tied to that PPS too.

I am still interested by a scope with 3GHz BW and >10Gsps with en external 10MHz ref.