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

[paul swed]

Adrian I had the same thing in the same unit. I guess the electrolytic's
were bad in allowing hum through. The tants go Bang and burn. Though all
caps can go bang I suspect.
Paul
WB8TSL

On Sun, Feb 24, 2019 at 5:04 PM Adrian Godwin <artgodwin at gmail.com> wrote:

> Just to sneak that back on-topic .. the most recent tant failure I had was
> in a KS-24361. It was after the dc-dc converter so it didn't look like a
> short to the input - it just increased the current draw. Running off a
> cheap laptop supply, which overheated and melted instead of shutting down
> or blowing a fuse. It took out the breaker for the whole ring main.
>
> Replacing the tant was the only action necessary for the KS-24361 itself.
> No other internal damage.
>
> On Sun, Feb 24, 2019 at 2:02 PM Adrian Godwin <artgodwin at gmail.com> wrote:
>
> > 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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> >
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