[time-nuts] HP Stories: An architectural view of the HP 5060/5061 and awkward oscillator adjustments.

[Adrian Godwin]

I think I've had as many shorted-out tants as dried-out electrolytics. It's
just that they appear in 80s gear instead of 60s. Then there was the flood
of high-esr electrolytics from when - early 2000s ?


On Sun, Feb 24, 2019 at 1:10 PM Rice, Hugh (IPH Writing Systems) <
hugh.rice at hp.com> wrote:

> Several people have asked about the Len Cutler ban on Aluminum
> Electrolytic Capacitors in HP Frequency Standards.   Rick Karlquist could
> shed more light on this too.   The legend of the ban was passed along to
> me, perhaps by Lou Mueller, who liked to tell stories of the old days.   In
> 1985, we were not taking the ban literally.   For example, the 2400uF main
> power supply filter capacitor was AL-Electrolytic, as were a few other
> smaller capacitors on the power regulator.   I sidestepped the capacitor
> issues on my simple battery charger by not having a filter cap after the
> transformer/full-wave-bridge, and just used 120 Hz pulses, since the
> battery didn't care about DC vs. pulsed DC.   (I thought it was pretty
> clever to leave out the main filter cap.)     Where possible, Tantalum
> capacitors were used.    For the few places where AL caps were used, they
> were heavily de-rated, operating at 50% of rated voltage for example.
>
> As one reader pointed out, back in the 1965 when the 5060A was developed,
> AL-Electrolytic caps were likely a lot less reliable than in 1985 when I
> worked on the 5061B.
>
>
> From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of Rice,
> Hugh (IPH Writing Systems)
> Sent: Saturday, February 23, 2019 8:49 PM
> To: time-nuts at lists.febo.com
> Subject: [time-nuts] HP Stories: An architectural view of the HP 5060/5061
> and awkward oscillator adjustments.
>
> Hello Time-Nuts,
>
> .... Stuff deleted .....
>
>
> It was fantastically reliable. Only linear power circuits, with robust
> heat sinking of all power devices. The legendary Len Cutler ban on aluminum
> electrolytic capacitors. 5060s were still in use in 1985, after 20 years of
> constant operation. Likewise, 5061As were abundant in time standards for
> 25+ years until they were replaced by the 5071A in the 1990s.
>
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