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High Stability 10MHz OCXO Upgrade for Racal Dana 19xx Series Frequency Counters and Timers
A high performance OCXO upgrade module to be used with the counter/timers originally fitted with the "Opt 04C" unovened crystal or "Opt 04T" TCXO 10MHz references.
Racal Dana 1991 Universal Counter
Racal Dana 1992 Universal Counter
Racal Dana 1998 Frequency Counter
Racal Dana 1999 Frequency Counter


Many of these Counter/Timers were originally fitted with a basic 10 MHz Crystal Reference PCB or the Opt 04T Temperature Compensated Crystal module. These gave frequency accuracies of just 10E-6 or 1E-6 respectively.
Our OCXO Upgrade PCB has a small OCXO module giving at least 2 orders of magnitude improvement on these original boards giving a stability of better than 1E-8.

Temperature Stability: 0 to 70 degrees C is better then 1E-8  (3 orders of magnitude better than the 04C option)
Ageing: 5E-10 per day, 1E7 per year.
Fitting instructions:

Fitting is easy and takes 5 minutes and you just need a small Posi-Drive/Philips screwdriver.


  • Unplug the counter from its supply
  • Remove the rear bezel (2 screws) noting which way up it was orientated as it only fits back on one way.
  • Slide off the case
  • The original reference PCB is mounted by a single screw and into a 5 pin header on the PCB. See photos. Remove the screw and the original PCB taking care not to lose the screw and washer.
  • Mount the new PCB into the counter as shown in the photos and secure with the screw. The rear mounted adjustment trimmer need to point towards the back panel
    Take care to make sure you have aligned all the pins on the main board with the socket on the new oscillator PCB
  • Reassemble the case and rear bezel.


The oscillator PCBs are soak tested for 24 hours then aligned against our GNSS Disciplined 10MHz reference before shipping. If you need to adjust/trim further with a local 10MHz source you trust, the adjustment pot is accessible from the rear panel.
The OCXO PCBs come with a 12 month warranty against failure.

Racal Dana Frequency Counter 10 MHZ reference OCXO Upgrade PCB

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