Tektronix 1751 Vector Monitor/Analyser - Page 1
Forum section: electronics / general

author: TheAmmoniacal
author_rank: Unknown
timestamp: February 20, 2014, 07:44:53 pm
content: I'm just in the beginning or start of my electrical hobbyist "career", not very knowledgeable yet, but sufficiently curious. I know that an oscilloscope is a very important tool for the electrical engineer, and I know the basics of how it works and operates. But just the other day I found an ebay auction for a "Tektronix 1751 Oscilloscope/Vector Monitor", assuming this device was an analog oscilloscope (which could be a good educational tool), i put in a max bid of $35 as more of a gag - I didn't read or research it in much details - but I won it, and it's been shipped.As I got the email that I won it, I started doing my research, and it turns out this isn't an oscilloscope after all. All I've basically managed to learn about it is that the electron deflection in the CRT is by electrostatic plates. So if anyone knows more about this device, and can understand more of the literature, could you explain what this is? - that would be much appreciated. Manual/Service manual:https://dl.dropboxusercontent.com/u/15526481/docs/070847006_0.pdfCan it be used as an oscilloscope at all? How will it behave if I connect a probe and start connecting it to AC circuits? How much can I learn from a waveform on it? If it can't be used as an oscilloscope, what other applications could it have in a hobbyist-setting?Thank you for any answers!

author: fcb
author_rank: Super Contributor
timestamp: February 20, 2014, 08:01:19 pm
content: This unit is a piece of kit that used to be (superseded by technology) very useful in broadcast television - and quite expensive.Basically it is not going to do anything you want (it can be used as an oscilloscope, but only for video signals), I would do a teardown on it when you get it - they are very well made!

author: N2IXK
author_rank: Frequent Contributor
timestamp: February 20, 2014, 08:09:18 pm
content: This is an oscilloscope, just not a general-purpose scope.It is a combination waveform monitor and vectorscope, used for monitoring and analyzing composite video signals in broadcast applications. The 1751 is intended for use with the PAL video standard.The waveform monitor mode is closest to a standard oscilloscope, in that it displays voltage in the vertical axis, and time on the horizontal. But the horizontal sweep speeds are limited to 4 choices, to display 1 or 2 fields, or 1 or 2 lines of the video signal. The vertical amplifier will also have various filters to pass or remove various components of the signal (luma, chroma, burst) for detailed examination of various aspects of the overall signal. Used for setting gain, pedestal, clipping levels, etc. The triggering system is designed to allow you to look at any one of the scan lines individually, so you can check for specific lines during the vertical interval which are used for special functions (timecode, closed captioning, teletext, VIR color correction, etc.).The vectorscope mode is used solely for looking at the chroma portion of a video signal, and gives a polar coordinate plot of the chrominance signal, with the circular position giving the phase angle (hue), and the distance from the center of the screen giving the intensity (saturation). Very useful for setting up color balance on cameras, etc, when used with a test chart, or checking phase shifts, etc. when used with a test pattern generator.Great stuff if you play around with analog PAL video gear, but not terribly useful otherwise, I'm afraid.

author: Swake
author_rank: Frequent Contributor
timestamp: February 28, 2014, 11:59:53 am
content: Do these devices have both a X and a Y input or something equivalent?And a Z too?Me thinking of building some cheap spectrum analyzer like instrument.

author: N2IXK
author_rank: Frequent Contributor
timestamp: February 28, 2014, 01:35:48 pm
content: My Tektronix 1720 vectorscope has rear panel X-Y inputs, intended for monitoring stereo audio signals. No Z axis input that I remember, though.Real X-Y display monitors (with Z axis input) are fairly common in surplus, and usually available cheaply:http://www.ebay.com/itm/Tektronix-602-X-Y-Display-/351011237695Something like that would be a better start for a homebrew SA than a converted vectorscope, if only for the more useful standard grid graticule (instead of the specialized graticule on a video vectorscope).

author: Swake
author_rank: Frequent Contributor
timestamp: February 28, 2014, 03:00:50 pm
content: Thanks for your answer.No need for a large bandwidth as a down-converter will be upfront the display, but analog signal like bandwidth is a little slow :-D. And very good point about the graticule.I haven't been able to find decent priced X-Y scopes on this side of the globe. As it is not for a 'serious' nor 'business level' project the budget is on the very low end. And admittedly I'm not really aware of what equipment existed so searches aren't efficient. Ho well... probably I can score a cheap 20MHz scope someware.

author: TerraHertz
author_rank: Super Contributor
timestamp: March 04, 2014, 03:55:58 am
content: Quote from: TheAmmoniacal on February 20, 2014, 07:44:53 pmHeh. I have to admit I've bought a few 'ebay mysteries' myself. Not so much recently. Best to do the research before bidding.QuoteUnfortunately for you, it's very specific to observing the phase accuracy of PAL composite video waveforms, and the video signal. Not useful for anything else. Also PAL signal test equipment is rather obsolete now, in the digital video era. The inputs all require 75 ohm coax, 1Vpp video signals, and the circuits will expect video sync signals and try to lock to them. Definitely not usable for general signal viewing.But... I used to work with professional video equipment long ago, and so for sentimental reasons collect some analog video gear. So long as it doesn't cost much. I don't suppose you are in Australia, ideally in Sydney? I'd buy it off you for what you paid, if I could pick it up or it could be shipped cheaply.