[time-nuts] Aging 5065A ?

[Bob kb8tq]

Hi



> On Oct 7, 2020, at 10:34 AM, Ulf Kylenfall via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Regarding the quest to keep a 5065A running... 
> 
> 
> The 5065 in my hobby corner was equipped with the firstversion of the AC-Amplifier (A7) that did not have a frequency
> selective 2nd harmonic detector. So I copied the later
> design but made possible the use of selected polyester
> precision audio capacitors for the resonant parts and
> also replaced the 709's not with 741's but OP07.
> 
> That design was uploaded to KO4BB (Complete with layout
> and gerber /NC-data should anyone want to copy it.)
> I have not received any comments but it works 
> really fine.
> 
> The Rb cavity was equipped with a thermal breaker
> recommended by Corby D. The linear power supply
> was replaced with a switched 24V unit (with DC filtering!)
> and the instrument now runs pretty cool. The only heat
> I can feel with my hands are just right above the
> Rb cavity.
> 
> I wonder how many 5065A's that are in professional use
> today. Or if all have been salvaged by time-nuts...

There are apparently one or more “pro” users of the 5065 that gobble them
up on eBay. It seems that their needs are small enough that they are ok doing
things this way. 

I *do* find it a bit surprising that nobody makes / sells a “lab grade” Rb anymore. 
Given its (likely) small market and (certainly) high price it is not a really big 
surprise …...

Bob

> 
> Ulf KylenfallSM6GXV
> 
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