Tektronix Oscilloscope - Opinions Please

[Kazooman]

I am looking for a good used scope. What do you think about this one from ebay?

Thanks for any advice you can offer.

eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

[JoeM]

That's a nice scope, maybe overkill for guitar amp use. The seller refurbs these, you might contact him and ask what other scopes he has. I know from time to time he has Tek 465s. At least buying from him you know it's working.

[Steve Conner]

Yeah, the 485 is nice. It's a high performance scope (overkill for audio work indeed) but surprisingly small and portable. If it was in the UK, I'd be bidding

The only thing about it is, it has quite a bizarre switchmode power supply, Tek's first foray into such things. If that ever blows, you're in for a fun time trying to fix it.

The 465 was supposedly Tek's most popular scope ever, you could hardly go wrong buying one.

PS: I'd say it is overkill in a good way. The Tek scopes were solid precision instruments, much nicer to use than some 20MHz Hitachi junker. And the fast ones should have a 20MHz bandwidth limit button that lets them impersonate a cheap scope, but with a much clearer display. The BW limit is handy for audio as it improves the scope's noise floor too.

[Kazooman]

Thanks for the replies. I also posted my question in the Amp Garage forum and got similar responses.

The problem I have been finding with used scopes on ebay and elsewhere is that they are usually sold "as is" with no calibration. I am concerned that I'll get a scope that I can't trust. This guy seems to know what he is talking about and he has great feedback.

I'll have to keep looking, but I am tempted by this one!

Thanks

[Steve Conner]

Like I said, if the seller was local I'd buy it! isn't he even offering a warranty?

[JoeM]

The seller is a member of the Tek scopes group on Yahoo. I've had correspondence with him, seems like a nice guy. I think he's a retired electrical engineer. He buys old Tek scopes and does a complete refurb and calibration on them and then sells them back on e-bay. So many scopes you'll see on e-bay only state something like "from a working environment". So in this case you know it's in working order.

[km6xz]

The 485 had only two real knocks, only 5mv/div max vertical deflection and a relatively small display. The display was smaller to get visible traces at such high sweep rates. Otherwise, it is a great scope that will out last most users by a decade or more. IF the probes included are original Tek, 350Mhz probes, $350 is a steal for the combination. The probes cost more than that.
It is a complex scope so repairing it, if needed, could be frustrating if you are not into test instrument repair that takes a little more attention to detail than guitar amps or pro audio gear.
As others have mentioned the 465 in its various incarnations, are bench standards, easier to repair, robust and reasonably priced. The lowest price version is the most rugged version, the 465M which was a military mainstay bought in large numbers as one of the first general purpose commercial test instruments that did not require a special ruggedized military version. It has a molded Lexan case and cover that was rejected by hobbyists as not looking like a "real" Tektronix so they go for cheap...maybe 1/2 the price of a working 465a or b.
About the fastest general purpose portable scopes was 400Mhz so if you have any need for that sort of bandwidth...I do...the 485 is the tool to use if you want portable. The 74xx series lab scopes are too big for field use but some where faster and more versatile due to their vast array of plug-in modules. A very useful plug in for all sorts or high end audio use or switching power supply work are the differential amplifier plug-ins. There were plugins for curve tracing, spectrum analyzer, logic plug-ins etc. Due to being large, those great lab scopes are relatively cheap. They are also large enough to need a scope cart to get it close the DUT. Scope carts are very useful for even the portable scopes like the small compact carts intended for the 465 series.

Bottom line, $500 for Buy it Now is a little high but a good investment for a income producing shop, but the reserve price is worth waiting for last minute bidding to try to get it for a hundred or so less. Ask about the probes....it is important. Cheap aftermarket probes will limit the usefulness of the potential performance of the scope.
Personally, I enjoy test gear a lot more than audio gear, it is built well, engineered well and worth keeping in good shape. When I had my shop, it was a veritable museum of older and recent lab type test instruments for just about any parameter to be measured, with dozens of Tektronix scopes, hundreds of pieces of HP/Aligent test instruments, a dozen or so Sound Technology generators/analyzers, a Dual Domain Audio Precision 2, 2 tube curve tracers and a couple transistor curve tracers and spectrum analyzers and generators to 10s of gigahertz. When I was collecting all that gear, there were a couple high tech swamp meets every month in the area that featured primarily lab type test equipment visited by a few thousands people every event. That was before eBay took over and boosted prices so much by offering that gear to a wider audience world wide. Most of what I see on eBay now is junk sold as parts units however.

Edit: I reread the offering and see that it does not include the probes but 100Mhz probes are available for $100.

[Mars Amp Repair]

tech scope

Hello,
I have been too busy running my business as of late to be a part of the forum. I finally have a day off.

I have a total of 6 techs including myself & have found that GW Instek makes a very reliable & good quality scope for the dough...esp when you have to purchase 6 of them.

we have the 20mhz dual trace model for most of the benches. I think the model number is GOS-622 which I bought for about $120.00ea. I also have 2ea 100mhz models 6112's that have digital control & readouts on the screen as well as the ability to set cursors to measure the wavelength & voltage, however I believe the processing is still analogue.

I have had these scopes for more than 5 years & have never had a stitch of trouble with any of them. They were all purchased on EBay as used items from reputable suppliers.

Oh yeah, one of them I had to clean the vertical v/div encoder when I first got it, but got price cut down to about 1/2 as a result. it was an easy fix.
The 622's I got for an average of $120ea when I noticed the 6112's selling for about $200.00ea. They are so much more scope than the 622's, I just purchase them now. there's one of them on ebay right now for $129.00.

So if you don't need the prestige of the Techtronix name on there & are using the scope primarily for audio, you might consider these super affordable guys. glen

[Kazooman]

Thanks for the good report on the Instek scopes. Based on the feedback I received here and on the Amp Garage forum I decided to forget the ebay listing I mentioned above. I ran across the Instek website and was impressed. I was going to post a followup question to see what people thought about their products and you have already taken care of that. I was looking at their digital scopes and was interested in the entry 25 MHz model. It turns out that this and several other scopes on their website have been discontinued. The entry level replacement is now the GDS-1052 -U. Once again I am in overkill land, but getting closer to reality. $346 new with two switchable probes. Lifetime warranty.

I'll continue to look at the other Instek models and check out ebay. I don't have the gear to calibrate a scope properly so many from ebay would be a problem for me.

[Steve Conner]

I wouldn't be surprised if the GW Instek DSOs were just rebadged Rigols. Rumour has it that Rigol makes the entry-level DSOs for everyone including Agilent. So maybe you can get a better deal buying a Rigol, or maybe you'd rather have the GW lifetime warranty.

[Kazooman]

Steve,

Thanks for the tip. The Rigol and Instek scopes certainly look like clones. I checked the Rigol website and their entry level scope is also a 50 MHZ model. It has a higher sampling rate than the Instek and from what I have seen that translates into a little higher price. It is certainly less than the Instek with that kind of sampling rate.

The interesting thing that I ran across is that that scope (DS 1052E) apparently has the exact same hardware as the corresponding 100 MHz scope. Someone figured out a software hack to convert the 50 into the 100. I wouldn't try this, since I don't need the rate and wouldn't want to void the warranty, but it begs the question of just what you are getting when you pay the extra money for the better scope. The folks who try the hack probably don't have the right probes to support the bandwidth.

[Steve Conner]

Yep, I heard about Rigol from the guys over at 4hv.org. A few of them bought the Rigol scopes and seemed quite pleased. They also said that they tried the hack and it works.

What are you getting for your money? 2 possibilities:

1. The 25 and 50MHz models might have the same digital circuitry as the 100 but a cheaper analog front end. The hack allows you to sample at 100MHz but the results wouldn't be as good as if you bought the actual 100MHz model.

2. They're all identical and the bandwidth limit is for marketing purposes. In this age of mass production, it's maybe possible that the extra expense of having 3 different models each with 1/3 the production volume is greater than the hit taken by selling the 100MHz model as a 25MHz one at a lower price. (Maybe some users will even "upgrade" and buy the same scope twice )

You be the judge. Smug Rigol owners who've done the hack obviously claim 2.

[Mars Amp Repair]

yep, I was just about to put this link to the Tequipment site where a guy reviews the scope in a couple of short U-tubes. He also disassembles it to show you how it's built.

Rigol Oscilloscope Independant Video Reviews

g

[Kazooman]

Thanks again to everyone for the good advice. I decided to go ahead and just ordered a Rigol DS1052E. I am certain that it will satisfy all of my needs.

[km6xz]

#2 with a footnote might be the reason for price difference, the speed rating of the major parts: the ADC's and Signal Processor might be different for the same part number hence a different cost and retail price.

I never liked the digital scopes for small signal work, like analog noise display but there is a lot of performance and features of the money. I was at a local small neighborhood electronics store yesterday which I had never heard about and saw they had a scope that looked identical to the Rigol lower bandwidth model but was rated a 40Mhz for an attractive price. The brand was ATT. It was so small and light that it would be a good option for field work. I went there because it had an advertised price on lab type regulated power supplies for 60% of the price that all the other supply stores had them for. The model I wanted was sold out so I ordered one but it might not be delivered before I return to California on the 12th since until the 10th the whole country in on holiday.