Re: UNUSUAL CRT Instruments?

Don Black <donald_black@...>

In the fifties there was a Marconi TV station synch pulse generator that used diode pump dividers. A blocking oscillator provided pulses to a diode rectifier that charged the following blocking oscillator grid circuit capacitor until it reached the trigger threshold (when it triggered it discharged the grid for the next cycle). By setting the adjustable time constant the number of pulses needed to trigger the following stage could be set for the required division (divide by 5 and 2 I think). There was a 1" CRT built in that could monitor any grid and allow that divider to be stable at the required division.
There was a HP oscillograph recorder that wrote onto a paper scroll chart with a very high intensity CRT which allowed much faster signals than a pen chart recorder. The tube was very flat and I believe only scanned across the paper, the other movement was due to the paper movement. I saw one parted out but never operating.

Don Black.

On 04-Sep-13 10:51 PM, Daniel Koller wrote:

Hello folks,

  This past February I picked up a unique instrument, an LA800D WWV comparator, at a hamfest. Ever since then I've been fascinated by it
 - one might say obsessed.  The instrument in question has a small CRT in it, which it displays a circular pattern drawn by the beam
being deflected synchronously with the WWV-derived frequency.  The intensity of the beam is modulated by a user-provided frequency.  The resulting
display is that of a semi-circle which is stationary when the user's frequency is the same as the WWV frequency.  As the user's oscillator drifts,
the semi-circle begins to turn at a rate proportional to the frequency error.  It's a fascinating and brilliantly elegant use of an
instrument-integrated CRT.

  This got me to wondering about what other sorts of "non typical" CRT displays might exist out there and I thought I would mine the HP and 
Tek groups's expertise for suggestions.  Can anyone suggest other instruments which have an integrated CRT, but use it in a manner OTHER THAN
then the usual Voltage vs. time of an oscilloscope?  Alternatively, if the x-axis is time, is it integrated in some unique way?

  I list below some examples that I either own or that I have found, that fit into this category.  I'd like to expand the list.

1) FR-4/U frequency meter part of AN/URM-79 or AN/URM-82.
   An example is here (no affiliation):

   I actually have one of these things.  I can't remember where I got it though.  This is a really neat instrument.  The gist of it
is that you mix an incoming frequency with a harmonic of a 1.25 MHz crystal oven-derived source.  After setting up a Lissajous pattern on the
small built in CRT, you look up the dial settings in an attached book to get the frequency, accurate to 1 part in 10^5.  It covers 100Khz to
20 MHz.  

2) A similar example is probably the HP 100C and 100E oven-stabilized crystal oscillator.  These had built-in CRTs to display the 
dividing ratio in Lissajous patterns.  

3) the only example of an integrated X-Y scope that I have is one I built myself based on the Amateur Scientist in the May 1963 issue of
Scientific American.  In this case a pair of crossed loops picks up the impulse generated by a lightning strike and displays them on the
x-y axes of a scope.  The z-axis is modulated by the detected electric field so you get a vector in the direction of the strike.  

4)  I've recently been turned on to the integrated-display Quad receivers, of which the Marantz 4400 is the epitome.   I really wish I had the disposable cash to pick up a 4400.  The 4400's display not only 
acts as an x-y scope to display the outputs of each of the 4 speakers, but can also be switched to tune the receiver, so it
serves as a simple spectrum analyzer.

5)  The Panadaptor/Panoramic Analyzer type of tuner.  e.g.
In later receivers, the separate box was integrated into the communications receiver chassis, but either way it counts.
Essentially, these are spectrum analyzers with the displayed center frequency tuned to the receiver's frequency.
I'd love to have a Panalyzer with a 455 KHz IF to hook up to my standard AM/FM receiver.

...I think that's a CRT in there, though I am not sure how this thing works.  I am presuming that the HV for the CRT comes from the spark itself.

7) Loran Receivers - I know some of these had built in CRTs.  I am not sure what they displayed exactly.  Too bad Loran has been silenced.

8) chuck Harris pointed me is this direction - the very earliest computer systems used a CRT to display the innards of the computer's operation.  
Connect a DAQ to the address bus and display it on the X-axis and another DAQ to the data bus and display it on y.  The resulting display will
show which addresses are accessed most frequently and if the program is stuck in a loop, the display will literally show a loop on the screen.
The best example I have found of a photo of this sort of display is here:  (third photo from the bottom)
The middle CRT appears to be the output of a Williams tube, but the other two appear to be displaying address space on the X-axis.
It seems this would be an awesome project for something like an IBM PC.

9) Williams tube - was an early form of storage for digital computers:

10) RADAR - certainly a non-typical display.  One example that comes up a lot on the net is a reconstruction of a German RADAR,
...which has very detailed descriptions of the various circular scope traces.

11) ??

Does anyone know if line CRTs (i.e. CRTs with only one deflection axis) were ever used for something other than scanning documents?
I'm curious to hear what other suggestions folks may have.


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