Deciding on an USED oscilloscope...what to look for?
Too_Many_Tools
Posts: 765
I have access to a number of USED HP/Tek analog/digital oscilloscopes from the 80s and 90s that have been in storage...and have been offered what I wish to take.
So cost is not the problem...time and what to look for in order to assess their condition is.
What does one look for in an used oscilloscope to insure that it is worth having in a home workshop?
What models to look at...and which models of both HP/Tek to avoid?
I have searched the archives and surprisely little has actually been discussed on this subject...evaluation of used test equipment is a topic that can benefit anyone looking to strench a home developer's budget.
A discloser...I have always liked the Tek 7xxx series...even when newer, lighter and more capable scopes were available.
Thanks for any advice.
So cost is not the problem...time and what to look for in order to assess their condition is.
What does one look for in an used oscilloscope to insure that it is worth having in a home workshop?
What models to look at...and which models of both HP/Tek to avoid?
I have searched the archives and surprisely little has actually been discussed on this subject...evaluation of used test equipment is a topic that can benefit anyone looking to strench a home developer's budget.
A discloser...I have always liked the Tek 7xxx series...even when newer, lighter and more capable scopes were available.
Thanks for any advice.
Comments
Google & ebay will give you a lot to go on when you have your list of model numbers.
Have fun!
Cheers,
Peter (pjv)
Definitely 100+ MHz, two or more channels plus external sync, delayed sweep, edge triggering, 10x high-impedance probes. Make sure to inquire about the switch functions and whether they all work. The TEK 2200-series, for example, used cam-actuated board-mounted tactile switches for their front-panel rotary controls. Unfortunately, the camshafts were not very stiff and bent over time, rendering the cams useless for actuating the switches.
-Phil
I will be getting ext. sync, delayed sweep and edge triggering with any of the selection I will likely choose.
Good probes of all types will be standard for any selection chosen.
I am aware of the sorted history of the 2200 series...they are known at the company as "The Throwaway Tek" scope since no repairs were available for them shortly after their production ended. Rumor has it that their HV sections were designed by the same people who did the Mission Impossible intros where the tapes always let the magic smoke out....
I have Googled previously...lots of hearsay and not alot of factual data out there as to the different models...therefore my posting for a request of advice from those on the board.
It is interesting to note how test equipment has undergone the same value engineering most manufactured products have ...with the reduced quality and limited lifetime that comes with it...and the nonexistent support after the sale.
Some of the equipment I have access to are older digital o-scopes...which are still out perfoming and out living their newer brethen due to that wonderful concept of value engineering that was not applied to their design and manufacture.
I'd recommend you visit the EEVblog forums. There are people there that are very knowledgeable about electronic test equipment, both old and new. There is a sub-forum dedicated to test equipment.
I have seen a number of nice expensive scopes/RF analyzers turn into very, very expensive paperweights because of it...because they were put into storage for a year and the battery (and the data it was storing) go dead.
The crazy thing is that manufacturer had farmed out all support...and the support company did not have the setting software (it was 3rd party and unobtainable)..so they couldn't cal it if they had wanted to.
Again throwaway scopes by a MAJOR manufacturer.
Thanks for the lead to EEV..I will follow up.
I mentioned the list above to illustrate what you can expect with tektronix. The older units were designed and built at a point when tek designed and had the chips such as the ccd storage arrays, preamps, trigger and sweep circuits custom designed and owned (i think) their own fab to make and assemble them. That is long history, and hence many parts are only available if you get lucky and find someone willing to sell one and can afford to pay their price. So, look at what your choices are and what parts are just to impossible to get. When my 2230 dies, it will go to ebay or elsewhere for parts. Go with a 2232 or similar if you want a good general purpose analog and digital hybrid. Be careful of the early Digitals they have their own issues, and lots of forums can fill you in such at the tek forum on yahoo. I would just pick one that fits your needs, will be assumed to be a one off, and will buy you enough time to save up for a nicer one such as the latest higher end Rigol or similar.
Personally, I remain quite biased towards the analog storage i.e. 465B and such for video and things under 100mhz but those are very rare with a good clear storage tube in them. On the positive side, they can eliminate bicep and wrist curls from your daily work out routine..\\
Have fun,
FF
Getting ALL of them, fixing broken ones with spares and sell them here or on EBAY for cheap?
Enjoy!
Mike
In the past we have had terrible problems with the HV section of the 22xx series...again unobtainable when they go.
In the past I have always had a second machine for parts..but the problem is a design problem will cause the same parts to go.
In respect to early digital scopes, surprisely HP was better than Tek in our experience. I have no real working knowledge of the newer Agilent equipment.
The 4xx series benefitted because many of the models were designed the military and Tek had to support them for many more years than a regular commercial offering.
You are quite right about Tek (and the former HP) having foundry access in the past...and it showed in their then cutting edge designs. The downside is that those limited supply of parts (ASICs, CCDs) are gone..long GONE. Same thing with Compaq, I used to favor early Compaq computers for their cutting edge implementations...the downside is that most everything was proprietary when upgrade time came..
I should mention that many electronics produced in the late 90's were/are having problems with bad tantalum caps...their ongoing failures will be destroying an entire generation of surplus test equipment.
The quantity of machines ranges in the hundreds..and to take them all would be unrealistic timewise and besides it would be greedy karmawise when others could use some of them too.
In respect to Ebay, it is definitely BUYER BEWARE...I have known some of the scopes that ended up sold to unsuspecting buyers by the local equipment dealers...I would NEVER buy a machine on Ebay unless I took personal delivery of it and tested it before cash exchanged hands.
Unobtainium - Nice!