[time-nuts] "The Penultimate HP5065 A15"

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Having one of the best HP5065A Rb's that Corby has seen right at 4 E-14 at 200 and 400 sec. I have been hands off. My age and macular hole on my right eye has impacted my hardware work. A recent test also shows very low aging over a 9 month period. But last September my environmental monitor was with Tom. The last month I have spend strictly on temperature to better understand what lab temperature effects the Rb.  This moment a 48 hour frequency test is in the works because there is a tropical storm that was a hurricane  20  miles east from me. Hope there are no power failures because the Rb is not on a UPS but like all my frequency equipment is on a Power Line Conditioner including the Rb. No power failure I will be able to share frequency versus pressure and temperature.

 

C field control Corby included by my request a fine control using a Vishay trim pot, knowing what I know today I would make the trim pot the coarse and the original Hp the fine. There is little need for coarse adjustment.

 

On the A 15 subject I keep hands off but Juerg is making some changes. In the AC mode there is up to 20 W heat generated between the transformer and the 24 V DC input. Our answer is a Buck Converter on the output of the AC supply down to 16 V for the Li Ion module that in turn feeds a Mean Well SD-50A-24 DC?DC converter. It 24 V output is not adjustable but that is a small price to pay. We have done tests feeding an OSA 8600 directly and have not seen any degradation. But in this case the A 15 board still does its part. The parts are not in the Rb but behind on the back.

 

A pressure, temperature and two DAC board is in the works.

Next hurricane the tests will be on a FRK/M100 because that will be my future HP5065A replacement.

 
Bert Kehren Palm City Florida 
 In a message dated 8/2/2020 4:38:31 AM Eastern Standard Time, time-nuts at lists.febo.com writes: 
Regarding 5065  "A15" When I was about to repair my 5065, the first thing I noticed was thequite high "+22-30V" and its impact on the dissipated heat from theseries regulator Q1. Therefore, I replaced the power transformer T1and the rectifiers with a linear regulated power supply providingfiltered 24V DC. The original circuitry incorporated a battery charger A2but since the accus was (very) dead, it was replaced with a diodejumper board A18 from a second scrapped unit. The original diodesgot hot. They were replaced with modern types. I will follow your progress with the new regulator board with great interest. Best Regards Ulf KylenfallSM6GXV_______________________________________________time-nuts mailing list -- time-nuts at lists.febo.comTo unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow the instructions there.