DDS Arbritrary Function Generator will it replace? - Page 1
Forum section: electronics / beginners

author: Docholiday
author_rank: Regular Contributor
timestamp: January 28, 2015, 06:19:55 pm
content: Can a DDS arbritary function generator subsitute or be able to replace a time mark generator?Thank you for your reply...

author: radiomog
author_rank: Regular Contributor
timestamp: January 28, 2015, 07:43:34 pm
content: I haven't done it myself, but in theory I don't see why it wouldn't, providing that your AWG can meet the marker specifics you need to create.

author: Docholiday
author_rank: Regular Contributor
timestamp: January 28, 2015, 08:06:09 pm
content: I was thinking that too, but you know how theory goes.

author: radiomog
author_rank: Regular Contributor
timestamp: January 28, 2015, 08:19:08 pm
content: do you have the specifics on the marker? do you have an AWG to try it out on (not to mention the device you need to input to)?looking at the traces in this thread:https://www.eevblog.com/forum/reviews/tektronix-2901-time-mark-generator-tear-down-inspection/looks do-able with mine. just make sure your AWG has an accurate/stable timebase.

author: Docholiday
author_rank: Regular Contributor
timestamp: January 28, 2015, 08:50:31 pm
content: Iam still a new to this starting my third year in ee. My ee professor methodof teaching is theory, apply theory to a circuit design of your own, then for extra credit he brings in non functioning equipment in for repair or electronic equipment for calibration and tesing. I am in my 50's and my classmates are in their 20's so competition is stiff. I need to stay ahead of the game as my trig professor said practice makes permanent. Moving on, I elected to choose calibrating and testng scopes so I am trying to collect (buy) equipment thst I can use to practice with. I really do like the trouble shooting, repair, and calibration. I know weird huh? I have several (3) Tek 465B scopes for repair and calibration to practice on. The service manual requires the use of a time marker generator and this is where I think I can use a dds arbitrary sweep pattern generator instead.God! I love ee!

author: radiomog
author_rank: Regular Contributor
timestamp: January 28, 2015, 09:07:53 pm
content: ahh, grasshopper....you will learn much this way!sounds like lots of fun to be had.

author: w2aew
author_rank: Super Contributor
timestamp: January 28, 2015, 09:51:06 pm
content: Quote from: Docholiday on January 28, 2015, 06:19:55 pmIt all comes down to the required timing (frequency) accuracy you'll need to do your scope calibrations. I've used a Tek AFG3000 series arbitrary function generator, with it's reference tied into my frequency counter's reference output which has better frequency accuracy, to calibrate the timebase on some of my old analog scopes. The "exponential fall" waveform is very similar to the blips used on the old time-mark generators.

author: Docholiday
author_rank: Regular Contributor
timestamp: January 29, 2015, 12:42:31 am
content: Someone had mentioned this method to me before. It is supposed to be more accurate than the time marker gen is. But the only con is the tweaking of two devices to get the wave form you require. Been told it easy and hard to do. I can only afford to buy one or the other at the moment. I want to purchase a frequency counter, DDS arbritary sweep pattern generator, and a 3 channel 0-30 volt dc power supply. On flea bay there are Tek time base generators going for anywhere fron 90 to 250 dollars - but buyer beware. I think I may just go down the route you did and leave it that. Before I do that one last look at some pattern generator technology that allows me to program my own wave forms. The only caveot is that apparently the amplitude is fixed. If that is the case this will not work either. I will just go with your solution. Besides, I am repairing and calibrating electronic equipment decades old anyway and its not going to calibrate like it was when new. It will be close like hand gernades and horse shoes.Thanks,Nicholas

author: Electro Fan
author_rank: Super Contributor
timestamp: January 29, 2015, 08:30:50 am
content: Quote from: Docholiday on January 28, 2015, 08:50:31 pmYou are livin' the dream! Go for it! Congrats!

author: KJDS
author_rank: Super Contributor
timestamp: January 29, 2015, 09:29:01 am
content: If all you want is to calibrate the scope, then a function generator with adequate square wave will do.

author: Docholiday
author_rank: Regular Contributor
timestamp: January 29, 2015, 07:03:25 pm
content: That Tek 2901 looks like a good idea and I am going to see about getting one. I know of someone that has one and see if they are willing to sell it. But going the route with a function generator and frequency counter I am still doing.

author: timb
author_rank: Super Contributor
timestamp: January 30, 2015, 01:52:03 pm
content: For the older low bandwidth scopes a function generator with an accurate time base will work, however if you're trying to calibrate something like a 2400 series (300, 400MHz) you'll need a 1ns marker, which will be hard to do without an expensive AWG.I just picked up a smoking hot deal on eBay: A Tek PG506A, TG501 and SG503 with a 3-slot TM503 mainframe for $300.07! (That's a Calibration Generator, Timemark Generator and Leveled Sinewave Generator.)I'll be modifying the Timemark unit to accept an external 10MHz clock (you just change a few jumpers and add 74-series logic chip, details in the service manual). This will provide better accuracy than even the 5MHz Option 01.So deals are out there, you just have to be on the lookout! (The seller had two complete units up on different auctions, the other went for $380 I think.)Sent from my Smartphone

author: Docholiday
author_rank: Regular Contributor
timestamp: January 30, 2015, 05:03:52 pm
content: Is the TG501 the replacement/upgrade from the 2901?Nope! I got it wrong. Should have researched first. I wonder if there ever was an upgrade fron the Tek2901?

author: timb
author_rank: Super Contributor
timestamp: February 01, 2015, 05:23:10 pm
content: I'd say it *is* an upgrade from the 2901. It was made afterwards and had two revisions. It was sold into the early 90's before it was replaced with a combined calibration/time mark unit for the TMS5000 series mainframe. (Which could be controlled over GPIB for automated calibration.)The TG501 is basically required for calibration of Tek's last line of analog/CRT scopes. (2400 Series, 7000 Series Mainframes, etc.)It goes down to 1nS and up to 1S in a 5, 2, 1 pattern.Sent from my Smartphone

author: Docholiday
author_rank: Regular Contributor
timestamp: February 01, 2015, 06:30:39 pm
content: Thank you so much for the education. This is a never ending process. I looked at your suggestions on flea bay but I see prices are all over the place. Simular to the 2901 almost. Decsions, decsions I need to decide. Thank you again for your contribution and sharing what you know about this equipment.Nicholas