[time-nuts] Obscure HP T/F instruments in ebay.fr

Bill Byrom time at radio.sent.com
Sat Mar 21 16:05:54 EDT 2015


Warning: Discussion of old pre-1980 technology follows ...

The Computer History Museum in Mountain View, CA, is amazing. I wish I
hadn't sold my original issue Commodore PET 2001, but you can find
examples of this and a wide range of early computers from the
1940's/50's/60's/70's (such as SAGE and CDC6400/6600) at the museum:
http://www.computerhistory.org/ They have an operational Babbage
Difference Engine No. 2: http://www.computerhistory.org/babbage/

I have worked for Tektronix for 28 years. Many of you may be interested
in the vintageTEK website: http://www.vintagetek.org/ For those of you
who have read old Tektronix service manuals with schematics:
http://www.reprise.com/host/tektronix/humor/

Only a few of us existing Tektronix employees have been with the company
long enough to have been involved in selling and supporting analog CRT
oscilloscopes, TM500/TM5000 modular equipment, and the Tek
4051/4052/4054 (first all-in-one graphic desktop computers). Some of
these were obsolete years before I started Tek in 1987, but I was using
them in the late 1970's.

When I was a University of Texas Electrical Engineering student back in
the mid-1970's I built a device to compare the 3.5795454 MHz color burst
NTSC television signal (from a normal TV set color reference oscillator)
to an ovenized 5 MHz crystal oscillator using a 315/88 ratio TTL divider
in the PLL. I used my Tektronix government surplus RM45A + CA plugin
oscilloscope for this project. I also experimented with WWV 5/10/15 MHz
frequency comparisons, but in Austin Texas the propagation from Ft
Collins CO made this difficult to much better than 1 part in 10^7. The
color burst method let me make use of the major TV network's rubidium
standards. Unfortunately, by the late 1970's the networks were reading
the monthly time deviation reports from NBS (name of NIST before 1988),
and they would often manually readjust their rubidium standard magnetic
field to get the frequency error in the NBS comparison closer to zero.
Of course, this made the reliability of the time dissemination (phase of
the color burst signal) unreliable. If they had just let the rubidium
standard alone in a stable environment with no temperature or magnetic
field changes, the drift in the timing error could have been modeled and
corrections to the received signal made before reading the NBS monthly
error reports.

In my first job (late 70's to early 80's) we used Tektronix 7000 series
CRT scopes to compare the output of a Tracor rubidium standard with a
WWVB receiver and reference clocks in test instruments we were
calibrating. We were considering building a commercial product based on
my color burst recovery technique, but the random frequency adjustments
by the networks and the switching between network and local station
color burst reference clocks during local programming insertion caused
us to abandon this project. This was about 7 years before I started at
Tektronix.

--
Bill Byrom N5BB



On Fri, Mar 20, 2015, at 12:02 PM, Robert LaJeunesse wrote:
> While it may not be time-nut centric there is a great museum in
> Michigan that has collections of both clocks and technology, along
> with a couple Stradavarius violins and machinist tools used by Mr.
> Daimler. The Henry Ford Museum in Dearborn, MI has been actively
> enlarging their technology collection - having recently paid nearly $1
> million for an original Apple I built by Jobs & Wozniak. They also
> have Robert Moog's prototype music synthesizer. Might be time to
> interest them in adding precision time to their clock and technology
> collections.
>
> Bob LaJeunesse
>
>> Sent: Friday, March 20, 2015 at 1:33 AM From: "Bill Hawkins"
>> <bill at iaxs.net> To: "'Tom Van Baak'" <tvb at leapsecond.com>,
>> "'Discussion of precise time and frequency measurement'"
>> <time-nuts at febo.com> Subject: Re: [time-nuts] Obscure HP T/F
>> instruments in ebay.fr
>>
>> There are worse things than breaking up a collection.
>>
>> The Baaken Museum of Electricity in Life, near Minneapolis had a
>> wonderful series of devices that used electricity to examine or
>> prolong life, or to extract money from suckers. About 20 years ago,
>> someone felt that there wasn't enough traffic at the museum, so the
>> interesting exhibits were removed and the museum dumbed down for
>> children. A vampire might greet you at the door.
>>
>> It seems that modern business managers have no time for things that
>> don't draw crowds or fly off the shelves. If a museum or business
>> wants to serve a market niche, it must compete with the incessant
>> blizzard of advertising from the companies that just have to grow.
>> Combine that with such companies expectations of productivity, and no
>> one has time to search for interesting museums, never mind go to
>> national parks.
>>
>> I would have been fascinated by and supportive of the French HP
>> museum, had I known about it. I did not even dream such a place
>> existed, but it makes sense that it was in Europe. Amsterdam has a
>> science museum that lifts children's interest rather than going down
>> to the lowest level to draw more people.
>>
>> In regard to dumbing down, the movie "Idiocracy" seems predictive.
>>
>> Bill Hawkins
>>
>> P.S. The Pavek Museum of Broadcasting (radio) is still hanging on.
> _________________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the
> instructions there.



More information about the time-nuts mailing list