[time-nuts] HP 5065A super

ew ewkehren at aol.com
Thu Feb 22 07:00:54 EST 2018


In December I lucked out buying a HP5065A for a very reasonable price, as is not tested. Turns out it was not working and I was not able to fix it. Corby to the rescue. Corby and I have shared many projects over the past, go back over 15 years, as a matter of fact he introduced me to time-nuts. Took Corbe over a week to find the problem, a defective Rb87 reference cell. Never seen before, no crack visible but obviously no Rb87. Corby had a replacement and the result is that it is the third best 5065A he has ever worked with. The logical choice is the super conversion. Not dramatic improvement because it was already very good.
Now a step by step work over, including HP mods for later  units like replacing the 74196’s in the synthesizer module with 74LS196. May have been end of life of the 74196.
Now to the purpose of this post. The A9 module is after 88 a significant change and Corby sees an improvement against his Maser. We are doing a board and maybe some other will be interested.
Here are the issues
A    is the LT1793 the best choice the time constant is 0.05 seconds with a 10 K resistor and 5 uF Capacitor
B    should we add resistors and decoupling on the + - 15 volt op amp supplies
C    Gold plating the edge connecter,  does any one know a reasonable source, or is doing it at home an option and if yes, how best way to do so.
Bert Kehren


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