This past February I picked up a unique
instrument, an LA800D WWV comparator, at a
hamfest. Ever since then I've been fascinated by
- 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
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
the semi-circle begins to turn at a rate
proportional to the frequency error. It's a
fascinating and brilliantly elegant use of an
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
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
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
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
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.
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.
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
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
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
8) chuck Harris pointed me is this
direction - the very earliest computer systems
used a CRT to display the innards of the
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
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
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.
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.
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.