AC Line Voltage 34 Hour Log

Tektronix 7000 Series Equipment

I am doing some testing on recently acquired Tektronix 7000 series equipment.  Involved in these images is a Tektronix 7904A mainframe using a 7S12 TDR/Sampler plug in with an S52 pulse generator and S4 sampling head.

Tektronix 7904A Fast Rise Time Pulse

Tektronix 7904A Fast Rise Time Pulse

The rise time on of the pulse is about 32ps which translates to a bandwidth of about 11 GHz; all this for a few hundred dollars.

Shaun Merrigan

Numitron Clock Project

Numitrons are low voltage incandescent display devices perfected and marketed by RCA (see RCA advert above) in the early 1970’s.  I would call this a bridge technology as the display is incandescent, but can be driven by integrated circuits.   They were quickly displaced by solid state LED (light emitting diode) devices from the mid 1970’s onward.

This is a Numitron:

RCA Numitron Advert

The look and feel of a Numitron display appeals to me and I wanted to reboot my building and soldering skills , so I decided to build a Numitron clock.  I based my clock on the RCA DR2000 which has a beautiful 15mm display height and a board and parts kit (no longer available) from Richard White.  Here are some images of the construction process:

And here is an image series of the finished clock … Read More »

I recently acquired two HP/Symmetricom Z3805A GPS Disciplined Oscillator receiver/clocks.  These units seem to have several different configurations both inside the box and of the box itself, but all appear to have:

Two 10Mhz outputs
Two 1PPS outputs
24v DC power requirement

Inside the box, I have seen reports of:

HP 10811 DOXCO (10Mhz)
Symmetricom  DOXCO (5Mhz with a doubler)
MTI 260 DOXCO
16 channel GPS receiver (newer builds)
6 channel GPS receiver (older builds)

The box itself can be Samsung rack mount or HP benchtop.   My particular units were older  Samsung rackmount builds, but do have the desirable HP 10811 DOXCO.   Both units had older 6 channel GPS receivers that exhibited the 1024 week GPS rollover bug.  (That is, they displayed a date that was 1024 weeks in the past due to nature of the 10 bit week counter used in the receiver.)  I simply swapped the GPS … Read More »

Lucent KS-24361 HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

I have updated my Time and Frequency GPSCon pages to show my recently powered on Lucent KS-24361 HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system.

The GPSCon page can be found here: Lucent GPS

Here is a photo of the unit:

In a nutshell, these two units each contain a Double Oven Controlled Quartz Crystal Oscillator (DOCXO) made by Milliren (MTI).  Both of these oscillators are GPS disciplined using an onboard GPS timing receiver located in the REF 1 box. 

These are NOS (new old stock) surplus units which were manufactured around 2000.  The useful outputs are 10 and 15Mhz and 1PPS.  It will be very interesting to see how this unit performs over the long term.

Shaun Merrigan