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HP 5061B Cesium

Frequency Standard

Option 003 & 004

MSRP of the 5061B is $45,700.00


This HP 5061B Frequency Standard has the following features:

  • Rated Accuracy 2x10-12

  • Option 003 clock & standby power supply (Please read description). 

  • Option 004 High Performance Cesium Tube (Please read description). 

  • Quartz Oscillator Upgraded to 3010.

  • Front outputs for 1PPS, 10MHz, 5MHz, 1MHz & 100KHz

  • Rear outputs for 1PPS, 10MHz, 5MHz, 1MHz, 100KHz & several different outputs for control and sync functions.

  • AC and DC power inputs.

  • Copy of the Operating Information Manual

  • Copy of the Operation and Service Manual

High Performance Oscillator 3010 Upgrade


During our testing, the HP5061B demonstrated exceptional performance.    The 5061B locked and the system operated correctly.

We did not go through all the fine adjustments to get the maximum performance from the system, but what we saw was very impressive. 



For those of you that are well versed with the HP 5061B or other Cesium Clocks, our tests showed the following:

  • As we conducted tests the Beam current could easily max the IBeam meter.  This is an excellent indicator of tube life.  You can see the photos below of key parameters


  • After 24 hour warm up period, the unit displayed a solid lock. 


  • When locked, the system had a  combined uncertainty better then  spec.  This includes the combined uncertainty of the HP 5061B tracked against our  Agilent 53132A  counter locked to our Agilent 58503B GPS clock. We have not seen better performance with any other clock we have worked with.   Another item of note is that during warm up with the crystal oscillator alone.  It showed the best performance I have seen from a crystal oscillator. 


  • The standby power supply does not have the battery installed.


  • The ion pump on the 5061B was very high when the unit arrived.   This is typical of a unit that has been stored for an extended period of time.   After 24 hours, it dropped to a point where the 5061B had no problem locking but was still a bit high.  There are procedures in the manual for establishing a vacuum if the unit has been stored for an extended period and a cesium lock can not be established after a 24 hour warm up period.  These procedures require use of an external 3500 VDC 5ma power supply to establish a better vacuum before switching to normal operation. This may be necessary to achieve a better vacuum specification.


  • This HP 5061B  has tags on the rear showing option 003 (The clock and standby power supply) and 004 (high performance cesium tube) are installed but I am not sure the tube is the high performance version so check out the photos of the tube.  Be aware even though the stand by power supply and clock are installed, the batteries are not in the unit.


IBeam Current Set In Perfect Adjustment For Normal Operation


IBeam current can easily be adjusted to peg the meter,

 a good sign showing plenty of tube life.


Second Harmonic In Perfect Adjustment For Normal Operation


Ion Pump is a bit high, most likely due to long storage.


The instrument is in excellent physical condition.  Although it has a few minor dings and scratches that can be seen in the photos.    

Power cord is not included.  We will put a standard AC Power Connector on the unit if requested by the high bidder.




As our many customers will attest, we will do our very best to resolve any customer problems.  But our official policy is: 

  • All items sold are guaranteed against D.O.A. only. 
  • All claims must be made within 3 days of receipt. 
  • All warranties are void if the calibration / warranty seals are broken.



Shipping Policy

Buyer will pay $50.00 packing and shipping in the continental United States.  We will make every effort to ship within 24 hours of receipt of payment.  We ship with FedEx only.  We will be glad to ship with other carriers using the purchasers shipping account.  Please contact us to make any special shipping arrangements. For shipping rate research, our shipping address is Boulder, CO USA ---- Zip Code is 80305.

Foreign buyers:  Unless special provisions have been made, you are responsible for making your own shipping arrangements and all costs related to customs, duties & special packaging requirements.  Please do not ask us to quote you international shipping rates.  Use the address information above to research you own shipping rates.  You can email waltwhite@ascentconcepts.com to get the packaging fee, package weight and size for your research.  Items sold outside the USA are sold as is.  



 Payment Policy

We accept Credit Card payment through Paypal.   We accept Cashiers Check or Money Orders.




The equipment shown is a representation only.  We often have multiple units in stock so please email us with your needs.  We have a large inventory and can usually find any test and measurement item in a short time frame.------Inquires info@ascentconcept.com