Rubidium Frequency Standard

Page still under construction


In my quest for having an accurate and stable frequency reference standard, I've found that in the present time,  Rubidium oscillators are being offered for very reasonable prices on ebay.While studying at the various models offered and comparing the specs, I came to the conclusion that it would be nice to have a model that features an RS232 interface for monitoring and calibration purposes.

So I ordered a

Temex LPFRS-01 - 10MHz 

from a Honkong seller on ebay. It arrived a little over a week after ordering.

Interfacing was simple: The LPFRS just needs a stable DC supply between 18V and 30V. An old Laptop power adapter (18,5V) was perfectly suitable. The LPRFS outputs a +7dBm sinewave at 10MHz. A lock indicator output can be used to drive a (low current) LED. Locking occurs some 8 minutes after a cold start.

RS232 Rx/Tx lines can be directly connected to a DB9 connector for interfacing with a serial port of a PC/Laptop. It communicates at 1200baud, and some vital monitoring of the unit can be carried out thru this interface.

After some initial tests, which proved the unit was fully functional, I built it into a nice housing. (pictures follow).


Calibration of the LPFRS can be done through RS232 (coarse and fine adjustment of C-field) by means of issuing simple commands (see the LPFRS-01 reference manual).

Later it would show that after it's trip in the Postal service from Honkong to the Netherlands, the accuracy of the unit was still quite good: Better than 1/30Hz error on 10MHz).

For meaningful calibration, one needs a better Reference source. See  section about: GPSDO


Page modified by Eddy on 2012-01-11
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