| sansbury |
http://boston.craigslist.org/sob/ele/307672005.html
Leader LBO-511: one channel, no probes, $25, said to be in working condition. Looks like a 100Khz bandwidth? As you can see my knowledge is limited. It'd involve a nice 2-3 hour drive from Boston to Cape Cod and back so I don't want to bother unless it's usable for more than a $25 doorstop.
I am mostly interested in amp/preamp work at this point and not so much the digital stuff. I realize that I could get more for $100, $200, $400 etc. but if I can get an OK scope for the price of two martinis and save the rest for parts to build more stuff to test I'd rather do that. |
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| RetroAudio |
| it's not $25 with the gas money and time involved. don't be cheap when it comes to a scope but there's nothing wrong with a good deal either. and maybe consider a 2 channel scope at least, although 1 will still be good for a lot. |
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| SY |
| Don't cheap on important tools. Two channel, triggered and delayed sweep, at least 40MHz (100 is better), top tier maker. Yes, that will be closer to $150-250 than to $25, but you wouldn't work on your car with Bob The Builder plastic wrenches, would you? |
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| sansbury |
OK then, guy just told me he has someone driving down from even farther away than me (Cow Hampshire! 3 hours easy) to pick it up. But he also has this rig to sell for $200:
http://boston.craigslist.org/sob/ele/307634085.html
My concern is this thing would be serious overkill for a newb like me, and perhaps that if one part of it breaks, the whole thing is shot and I'm out $200.
-- Agilent / Hewlett Packard / 16500A Logic analyzer mainframe:
Consisting of 2 built-in 3.5 inch floppy disk drive, built-in RS-232 and GP-IB interfaces, Color touch screen.
-- (One) 16530A Timebase plug-in card:
This card is designed for use with the 16531A oscilloscope card and provides an Oscilloscope-on-a-Card capability.
-- (Two) 16531A 400MSa/S Oscilloscope cards:
This card is designed for use with the 16530A timebase card and provide an Oscilloscope-on-a-Card capability. Bandwidth of 100 MHz and sample rate of 400 MSa/s. Has 2 channels per card (for a total of 4 channels with 2 cards).
-- (Three) 10433A Probes
-- System Driver Disks
-- HP Thinkjet 2225A with GP-IB cable |
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| SY |
| For $200, stick to a good quality analog scope with a name like "Tektronix" on it. It will be the best money you've ever spent on this hobby. |
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| kscharf |
This is NOT a good scope for digital work. It would be fine for audio work. In it's day it was considered a tv scope, but would not be useful for today's digital HDTV etc.
You know, you can pick up an older used Tek on ebay for $100 or so.
I have an old Tek 453 scope that is STILL useful for digital work that I got for about $200-$300 years ago. |
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| nuvistor |
Tek 2215 show up on eBay regularly for < $100, 60MHz with delayed trigger, a budget analog scope from the early 80s, works fine for me.
HP 1220/1222 may be available for less, 15MHz, calibrated sweep but no delayed trigger. OK for audio frequency but may miss HF parasitic oscillation problems.
The Leader is certainly better than no scope at all. |
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| sansbury |
Well, the cheapo Leader was gone before I got to it so that choice is moot.
I live in Boston and see the next MIT flea market is this coming Sunday so I think I am going to hit that first, have to imagine there will be at least a few things to see there in or near my price range. Besides, part of the reason I love living in Boston is being able to say, "I'm going to the MIT flea market this weekend to look for an oscilloscope."
In case anyone is looking for it: http://www.mitflea.com/
I hate the idea of paying $40 for a scope on eBay and then paying $50 to ship it. |
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| EC8010 |
| quote: | Originally posted by sansbury
I hate the idea of paying $40 for a scope on eBay and then paying $50 to ship it. |
Well, there you have it, why waste money shipping a cheapo. Go for an analogue 'scope with "Tektronix" written on it. At least 60MHz, and preferably 100MHz. Definitely two channels, and it's nice to have delayed timebase (but not essential). As SY says, saving money on an oscilloscope is wasted money. Think about it; you're going to make measurements, and on the basis of those measurements you'll spend some money or rebuild something you already spent money on. Now, how much would it cost if your test equipment made you make the wrong choices?
I use a Tek 2213 60MHz analogue 'scope and a Tek TDS3032 300MHz digital 'scope. Stay away from digital 'scopes until you know far more. |
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| rcavictim |
| quote: | Originally posted by SY
but you wouldn't work on your car with Bob The Builder plastic wrenches, would you? |
Sy,
I think that is what many allegedly professional auto repair shops here in Ontario must use based on the cost and quality of the repairs we see. Aren`t Snap Off wrenches, a competing brand, also all made of plastic?
:D
I agree that it is a worthwile investment to get a high quality, all analog two channel o-scope with delayed TB and 100 MHz BW. They are not expensive bought surplus. The idea of a radio parts fleamarket held at MIT sounds like a lot of fun! We Canadians get nothing like that up here. Our military electronics surplus doesn`t get written off by the government until it is at least 100 years old and then it comes with ALL the capacitors removed making it worthless junk because they put totally untrained doofuses in charge of making the stuff PCB free. Guys that wouldn`t know it if a real PC Bee bit them in the a$$. |
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| Conrad Hoffman |
| Get a late model Tek scope, two channels, 100 Mhz, guaranteed working. Watch out for the earlier solid state models like the 465B. They're nice to work with when they work, but are old enough to be unreliable, and are difficult to service. Though I have one of those, I actually still use a "boat anchor" Tek 545B that uses tubes and is only 40 Mhz. You don't want one of those unless you know how to service it, have spare tubes, and need extra heat in the winter. On the upside, they practically give them away at hamfests- around here they often get left behind for the dumpster. On the further upside, with a 1A7A plug-in, I can make measurements down to microvolts per centimeter, albeit only to 1 Mhz. Very useful for sorting out ground and noise issues. The long tubes can also be focused much more sharply than the later better protected scopes. I recommend against the low end HP scopes (dim fuzzy traces), and Phillips scopes (unless you can get docs), and any of the non-name brands. Leader actually made some decent scopes, but parts are often needed, and impossible to get. I've used several Leaders and didn't dislike them, but stick with Tek. Digital scopes do some things very well, but aren't well suited to audio. I'd only pick up a digital scope if I already had an analog scope to fall back on. OTOH, for mostly digital and high level analog work at work, I wouldn't use anything else- they can help your productivity and documentation tremendously. |
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| I_Forgot |
| quote: | Originally posted by sansbury
-- Agilent / Hewlett Packard / 16500A Logic analyzer mainframe:
Consisting of 2 built-in 3.5 inch floppy disk drive, built-in RS-232 and GP-IB interfaces, Color touch screen. |
I would avoid this like a case of multi-drug resistant TB. I had some logic analyzers back when I used to deal in surplus electronic stuff and found that even a working logic analyzer is junk if you don't have a complete set of probes for it, and that is how they normally end up on the surplus market- missing probes. A set of probes will cost you a couple thousand dollars if you can find them.
Logic analyzer development and obsolescense are similar to that of PCs. They should be cheap, but since the probes and the analyzers are normally stored in two different cases, they are normally not found together on the surplus market. If you want to make some money, start hunting and reselling logic analyzer probes. There are a million surplus boxes out there that need probes to become functional.
I_F |
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| OzMikeH |
Once CROS get over about 15 years old you not only need to know how to use them, but how to repair them. switches get grotty, capacitors dry out. all sorts of issues. stay well away from anything made by Velleman too.
Getting one with a CRT is cheaper but bulkier so it will cost you a LOT more in freight, some digitals are only 2 inches thick.
dual channel is very useful for fault finding, I use two probes, one connected to the test signal source and fiddle the cal so I can exactly overlay the two traces to look for distortion. (this is where a nice sharp focus is important.
20MHz at least, 40Mhz better (go for a quality 20Mhz before a cheap 40MHz)
Good brand: Philips, tektronix, HP, have a look inside if you get a chance, the circuit board materials, screen printing etc will give you a good idea of quality.
my next project is restoring this old beast.
a 30kHz single channel Philips CRO. That's right, kilohertz... next to useless but how quaint! |
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| OzMikeH |
If you see anything like this avoid it, a great bit of gear if it's working correctly but it has 2 handles for a reason - they are extremely heavy. There are about 30 tubes in these, they only last for so long too.
that screen is about 5 or 6 inches across.
Looks like a great buy but you need a real smart old-timer tube freak to fix it. - any volunteers??
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| EC8010 |
Quaint indeed.
One other possibility (if you're offered one for free, and no postage) is a 20MHz dual channel Gould. They used to be very popular in university labs and they're almost bomb proof (they need to be, when dealing with students). The great advantage of these Goulds is that they use almost entirely discrete components so they're maintainable almost indefinitely. I'd concur with the advice to stay away from Tek 465 etc; you want the final generation analogue Teks. |
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| EC8010 |
| quote: | Originally posted by OzMikeH
Looks like a great buy but you need a real smart old-timer tube freak to fix it. - any volunteers?? |
Let's see, postage to UK and back... :D
I once bought a 555 for £10. Two handles for the oscilloscope, plus separate power supply (only one handle). Excellent source of useful bits. |
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| rcavictim |
| quote: | Originally posted by OzMikeH
If you see anything like this avoid it, a great bit of gear if it's working correctly but it has 2 handles for a reason - they are extremely heavy. There are about 30 tubes in these, they only last for so long too.
that screen is about 5 or 6 inches across.
Looks like a great buy but you need a real smart old-timer tube freak to fix it. - any volunteers??
|
I had three of those fresh from government surplus a couple of decades back and I referred to them as a 500 watt fan forced space heater with an o-scope screen to monitor their performance.
:D
I wish I still had them today as a source for tube amp parts! |
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| rcavictim |
| quote: | Originally posted by EC8010
Quaint indeed.
One other possibility (if you're offered one for free, and no postage) is a 20MHz dual channel Gould. They used to be very popular in university labs and they're almost bomb proof (they need to be, when dealing with students). The great advantage of these Goulds is that they use almost entirely discrete components so they're maintainable almost indefinitely. I'd concur with the advice to stay away from Tek 465 etc; you want the final generation analogue Teks. |
EC,
I have one of those Gould`s, a dual channel unit with a pretty much permanent position on my audio bench and that is what I primarily use there. Great scope for this purpose. I paid about $60 for mine a decade ago and have had no problems with it. Good suggestion!
For more demanding measurements associated with RF or fast stuff
I have a 120 MHz Delay timebase dual trace Philips (since almost new) that travels to where I need it on the property only. It has developed a flaky delay line which I fixed with a rubber elastic band instead of a $1000 repair. I agree with the other poster not to get a Philips. I also shuffle around here most often with my Tektronix 1740A dual trace delayed timebase (100 MHz?). I bought two of those for $40 each at the Rochester Hamfest and made one good one from both. I have a spare CRT and everything else for it as a result. Nice scope but the triggering is poor. That may be an actual circuit fault and not a characteristic of the model. I do not expect to own a digital scope.
I have a Tek 564 dual channel storage scope that sits on the equipment shelf in the lab. I haven`t used it in many years since it served for a decade as part of a real time Hydrogen line spectral line microwave receiver display. I also have the same scope without storage. What was that one, the 562 or something? There is also this old HP scope that I bought because it had a good 141T storage mainframe to use in my microwave spectrum analyzer. That one gets fired up occasionally.
I found a mint 5 inch, `Precision` brand TV service man`s scope from the 1950`s at a hamfest for $5 and bought it because it looks great in my collection of 1940`s vintage TV receivers in my home. That one works but needs a recap. Beautiful black wrinkle steel cabinet finish and black face highlighted with aluminum raised etched printing and border. Pointy black knobs. I would have given my eye teeth for that scope when I was a kid and it was almost new! Much better than the cheap Eico`s and Heathkit scopes of the same era. It actually has two accelerator sections on the scope tube bell IIRC and the detail to shielding inside is very good for the era. I`ll bet it was expensive.
Then there is this old 1960`s, 3 inch Telequipment rack mount scope .......
Gee I have accumulated a lot of stuff. :xeye: |
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| SY |
| That old Tek is not only a fine parts source, it's a source for the best terminal strips on the planet Earth. |
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| Apex Jr |
The older 500 series scopes are great sources for tubes
and as Sy stated those terminal strips, CERAMIC.
THere also good for movie props for period films from the
60's and are rentable or saleable too.
I agree with the above statments on the Tek 465 scopes
but wouldn't dismiss the update version 465B's
These are great scopes and now priced right just make
sure you get one that has there dual display.
The MIT Flea market sounds like fun, to bad it's so far
for me...
Steve @ Apex Jr. |
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| rcavictim |
| quote: | Originally posted by rcavictim
I also shuffle around here most often with my Tektronix 1740A dual trace delayed timebase (100 MHz?). |
Well, brain fart and all. I meant to say 1740A Hewlet Packard scope.
Yes those ceramic terminal strips in the old Tek series scopes and other gear would be great to use in DIY tube gear while you can still get silver bearing lead tin solder. Must think about that for my next tube project. Trouble is most of the gear I own that has `em inside I still use. :bawling: |
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| sansbury |
Well, the MIT flea was pretty lame--first one of the year and bad weather, I'll probably try going back a little later just to see whether that's typical. Lots of really cheap PC garbage and typical flea market junk, a little bit of interesting stuff around the edges.
I'm watching a couple of eBay options right now, particularly this one:
http://cgi.ebay.com/ws/eBayISAPI.dl...90329&rd=1&rd=1
Shipping was quoted to me by the seller at about $30, so about $175 all told. The specs on the scope itself appear to be pretty good, and there is a 5-day return warranty on it, though after $60 in shipping costs that's not a get-out-free card.
I've also found someone near me who has a couple of Tek 465s he bought surplus from an employer a few years ago. He is offering to sell me one for $90, with a no-questions-asked money back if I don't like it and he'd take PayPal if I wanted to do it that way. Even adding in probes and all this would probably net out to $120-$130. I'm waiting to see what the exact model is (A, B, or M) and what sort of condition it looks like.
Given the choice (Newish 20MHz/2-ch "cheap" scope for $175 vs. 465 for ~$130), what would you guys go with?
If I met the fellow to look at the Tek, are there any simple tests I can run without a signal generator on hand to make sure the thing isn't hopeless? I trust that I could get my money back from him if so, but would prefer to avoid waste of time.
EDIT: Also really tempted by this thing, which is stupid since it is the same price effectively as the Instek above and much less capable, but a lot more scope than I have now (none) and so nice and small! (9"x3.5"x11") and I live in a city studio apt. which already has too much **** in it. Portable is really nice for me...
http://cgi.ebay.com/ws/eBayISAPI.dl...80320&rd=1&rd=1 |
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| SY |
| The 465 would be my choice; best way to check it is with its own calibrator and a 10x probe. Make sure the square waves look good (you might have to adjust the probe's trimmer) and that they're the right height. |
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| EC8010 |
| Go for the 465, but check: Most importantly, look at any signal (the square wave from the built-in calibrator will be fine), make it about one large division high and use the shift control to move it up and down the screen. If the amplitude changes from the top to the bottom of the screen drop the 'scope like a hot potato. Changing amplitude indicates a blown output transistor in the "Y" deflection amplifier, and the hybrid containing that transistor is no longer available, so you're stuffed. |
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| Apex Jr |
I too am for the 465's
Make sure it has a letter after it, the B would be the best
and even better with a DM too. They came with a multimeter
or a counter attached to the scope..
Also check to see that it does have 2 traces and that the
trace is strong. Touching the BNC connectors with get
a wave and easy to check that way...
Steve @ Apex Jr. |
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| kscharf |
The Tek 465 is a nice scope, but it does have one problem ... crt failure.
The lab that maintained the scopes where I once worked kept a stock pile of spare crt's for all the scopes. The 465 - 475 series went through more crt replacements than any of the other models. The older 454's seemed to NEVER throw a crt, maybe they didn't push them as hard brightness wise.
Mind you the scopes saw a LOT of use (and abuse) so take it with a grain of salt. |
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| jackinnj |
| quote: | Originally posted by nuvistor
Tek 2215 show up on eBay regularly for < $100, 60MHz with delayed trigger, a budget analog scope from the early 80s, works fine for me. |
I am glad that your 2215 works well, it obviously hasn't had to take a bounce in an undergrad physics lab. I think that these are best avoided unless you can see it up close and personal. |
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| EC8010 |
| quote: | Originally posted by kscharf
The Tek 465 is a nice scope, but it does have one problem ... crt failure. |
How do you notice when the CRT has failed? As I recall, the 465 and 475 had particularly soggy CRTs anyway. My 485 had a nice sharp CRT before the EHT supply went west. |
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| jackinnj |
| quote: | Originally posted by rcavictim
Well, brain fart and all. I meant to say 1740A Hewlet Packard scope.
Yes those ceramic terminal strips in the old Tek series scopes and other gear would be great to use in DIY tube gear while you can still get silver bearing lead tin solder. Must think about that for my next tube project. Trouble is most of the gear I own that has `em inside I still use. |
The old Tek scopes still have one thing going for them -- they are much, much quieter than the digital ones which go for a couple thousand bucks -- yes you may only get 25 MHz of bandwidth but it isn't going to send all sorts of digital artifacts all over the room.
Since you're near the boston area you might consider going to the "Flea at MIT" -- every month one of the ham radio clubs has a flea market and you might find a good used Heath, B&K etc. scope for a couple of Jeffersons. |
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| EC8010 |
| quote: | Originally posted by jackinnj
The old Tek scopes still have one thing going for them -- they are much, much quieter than the digital ones which go for a couple thousand bucks -- yes you may only get 25 MHz of bandwidth but it isn't going to send all sorts of digital artifacts all over the room. |
I was recently reminded of this when I used a Tek 2245 that although an analogue 'scope, had a micro-controlled interface (you know the kind, twiddle a wobbly knob and wait for something to happen). There was clock noise on the trace at all times... |
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| jackinnj |
"Flea at MIT" -- next one is June 17
FLEA at MIT
*******************************************************************************
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August 19 September 16 and October 21, 2007
*******************************************************************************
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or 55 Albany St 02139
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MicroMechanical Fab, available for buyers, enter at
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for a map see http://maps.yahoo.com/py/maps
Entrances to the other buyers parking lots are at:
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480 Main St 02139
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lots for sellers !!!
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*** !!!! In our Traditional GARAGE and lot !!!! ****
so come rain or shine or super heat the Flea is on !!!
********* $1 buyers discount with hardcopy of this notice ********
COMPUTERS - ELECTRONICS - HAM RADIO - COMPUTERS - ELECTRONICS - HAM RADIO
FLEA all SUMMER at MIT
Sunday April 15th 2007
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Come to the city for a great flea - plenty of free parking.
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April thru October.
There is tailgate space for over 600 sellers and
free, off-street parking for >2000 cars!
Buyers admission is $5 (you get $1 off if
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and sellers spaces are $20 for the first and
$15 for each additional at the gate.
The flea will be held at the corner of Albany and
Main streets in Cambridge; right in the Kendall
Square area from 9AM to 2PM, with sellers set-up
time starting at 7AM.
SEASON PASS + Advance Discounts
A sellers discount season pass is available which
offers a 33% discount. See the registration form
for full seller info.
*** Attention Sellers ***
Prepaid vendors.. Season Pass or monthly,
will be admitted FIRST.
Separate lines will form prior to gate opening
for prepaid and nonprepaid vendors
!! RAIN or SHINE !! Have no fear of rain, a covered
well illuminated tailgate area is available for all
sellers (6'8" clearance).
Talk-in: 145.23- (PL 88.5) W1BOS/R and
W1XM/R-449.725/444.725 (PL 114.8/2A).
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For more info / advanced reservations 617 253 3776
********** $1 buyers discount with hard copy of this notice ************
*******************************************************************************
Steve Finberg W1GSL w1gsl@mit.edu
PO Box 82 MIT Br Cambridge MA 02139-7082 617 258 3754
******************************************************************************* |
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| sansbury |
I went to the Flea last weekend with high hopes, but it was honestly a pretty sorry affair, unless you were looking for large volumes of PC garbage. Or perhaps all the good stuff got picked off by 10:30 when I got there--not a single scope in sight.
BTW, what do people think of this piece? Not exactly a beginner's device and I can't find much on the web about it, but given my tiny apartment I'd love something smaller than a full-size bench unit.
http://cgi.ebay.com/ws/eBayISAPI.dl...DME:L:DBS:US:11 |
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| EC8010 |
Not with a sterilised barge pole.
Seriously, using a 'scope like that demands far more knowledge than you presently have. All digital 'scopes have their failings and can give odd results compared to an analogue 'scope if they're not set up perfectly for the task in hand. You need an analogue 'scope you can trust. Even I sometimes get caught out with my digital 'scope - and it has far fewer flaws than the one you have looked at. |
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| jackinnj |
| quote: | Originally posted by EC8010
Not with a sterilised barge pole.
Seriously, using a 'scope like that demands far more knowledge than you presently have. All digital 'scopes have their failings and can give odd results compared to an analogue 'scope if they're not set up perfectly for the task in hand. You need an analogue 'scope you can trust. Even I sometimes get caught out with my digital 'scope - and it has far fewer flaws than the one you have looked at. |
I bet you've never done this at 3:00 a.m. -- placed the digital scope probe on the schematic to find out what's wrong :) |
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| EC8010 |
| quote: | Originally posted by jackinnj
I bet you've never done this at 3:00 a.m. -- placed the digital scope probe on the schematic to find out what's wrong :) |
He, he! Did it give a better result than putting it on the circuit? Faultfinding at 03:00 is guaranteed to result in daftness.
I'll share a moment of daftness. We had an intermittent fault on a VT machine and I'd narrowed it down to one board, so I had the board out on an extender and waved a hot air gun over it to force the fault. I could then provoke the fault at will, but prodding with a screwdriver didn't work, so I stayed with the hot air gun, progressively narrow down the area of the board and following it in with the 'scope probe. It turns out that 400MHz Tek 'scope probes don't survive being too close to a hot air gun - the plastic softened and the tip fell off. Whoops. |
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| XEAGLEKEEPER |
Tek 2445 $255 off of ebay
4-channel 150mhz way overkill for audio.I used one like it as a stand-a-lone scope in the F-15 EW test station on a daily basis . While I was in the Force. And the price was right!!
The cursors are real handy no calculator needed for time/freq conversion and provides a digital readout for voltages as well as time and freq.I'm lazy..........
Dave |
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| sansbury |
OK, so I picked up the 465 along with many assurances that I could bring it back, full refund, no questions asked anytime in the next two weeks. Unfortunately I fear I may need to test the validity of that warranty.
Upon powering up, I get the following- while messing around with switches can make it do a variety of things, none of them seem "quite right" to use the technical term. Just to make clear, this is with one probe attached, but not connected to anything.
Of course, I don't really know how to use this anyway, so maybe I'm just not doing it right, or maybe it's a small thing to repair, assuming I had any idea how to do so.
Suggestions? |
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| Conrad Hoffman |
| That's a bit disturbing for not being connected to anything. Even hum should have a top half of the waveform. BTW, the 465 will go plenty bright enough to burn a permanent image into the CRT. You should never run so bright that there's a "bloom" around the trace. It may just be the photo, but if it really looks that way, turn the intensity down! Take a small piece of wire, hold it in your hand, and insert it in the input. You should be able to get a nice 60Hz trace, with both top and bottom. It should be stable if you line trigger, and stable if you adjust the normal triggering correctly. With no cable or anything, there should be no waveform, only a flat line, on any setting. |
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| sansbury |
| If I touch the tip of the probe with my finger it does change the pattern, but clean it definitely is not. |
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| SY |
| Finger-touch waveforms will generally not be clean. Can you get spiky peaks on the top? How does a clean AC waveform (like the secondary of a heater transformer) appear? |
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| sansbury |
| Measuring the 25V outputs off the trafo on my gainclone, I can get something that resembles a waveform, though it looks more like the matterhorn than a nice sine. I also tried sending a 500Hz wave through my system and measuring the positive on one of the input and output terminals, and it is picking up something, but I can't get it to look like anything recognizable. |
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| EC8010 |
| Does the 'scope produce a pair of straight lines with the inputs switched to "GND"? And at any setting of the volts/div switch? |
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| jackinnj |
Does the scope have "focus" and "astigmitism" functions -- you can twidle these as well.
If you short the probes together you should get a flat line. This scope also has a "ground" function on the vertical control panel -- if this is engaged and the line isn't flat then you've got a problem with the vertical amplifier. |
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| juergenk |
and it should have a buildin squarewave output!
Try to get a clean waveform using this calibration output.
Scopes have a lot of knobs, switches and settings. It is easy to get them misaligned. |
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| sansbury |
I can get a square wave but it's very finicky and has a weird distortion at the right side- see the pictures attached below. The effect is a little hard to capture on a still but these should give a sense of how it looks. I can move it around and the amplitude doesn't change but if it moves much away from the center it loses definition completely.
With the inputs set to "GND" I can't get a flat trace- I get a sawtooth-like trace as seen in my earlier picture a few posts above. |
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| SY |
| Give it back. It might be fixable, but maybe not, and it may be symptomatic of other problems. |
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| sansbury |
Well, just got back from New Hampshire (lovely day for a drive) with an Iwatsu SS-5710 4ch 60MHz scope which was verified to work reasonably properly before purchase, for $90. No probes or manuals, but the traces and calibration outputs were all solid.
Assuming I don't have any problems returning the 465, looks like I finally have myself enough equipment to debug that $10 op-amp buffer I've been trying to build :D |
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| EC8010 |
Ah yes, HF roll-off, a well-known problem whereby the signal falls off the end of the horizontal deflection ramp.
Sansbury: You are still murdering your tube. There shouldn't be any penumbra around your trace. The general rule with 'scopes is that if you can see the trace it's a tad too bright. (Lower brightness significantly helps focus.)
PS Don't take the HF roll-off comment seriously; I haven't a clue what would cause that very strange effect. |
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| sansbury |
| EC8010: Point taken--the penumbra is mostly a result of the photo, but thanks for the tip. Now that I have another (seemingly properly working) scope, I certainly don't want to cook it. |
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| EC8010 |
| Excellent. Now all you have to do is to learn how to get the most out of it. The great thing about oscilloscopes is that they are such wonderful tools that you keep on learning ways of getting more out of them. |
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| RetroAudio |
| sansbury - an Iwatsu is supposed to be a pretty good scope. When deciding on my first scope I checked out an Iwatsu at a place in Seattle and was impressed with the quality. The salesman (to be taken with a grain of salt of course) mentioned they were very big in Japan and were the Tektronix equivalent. Just operating the controls verified if was high quality. |
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| audioquest |
On my bench David and Goliath. Both are excellent scopes, but I have a little preference, despite the SIZE, for the 556 which can display 2 signals out of frequency or phase. You can even display XY on one channel and everything on the other AT THE SAME TIME !
Also excellent to heat up the garage in winter..... |
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| kscharf |
| quote: | Originally posted by audioquest
On my bench David and Goliath. Both are excellent scopes, but I have a little preference, despite the SIZE, for the 556 which can display 2 signals out of frequency or phase. You can even display XY on one channel and everything on the other AT THE SAME TIME !
Also excellent to heat up the garage in winter..... |
Now that's a rare bird. Hope your CRT never goes bad, 'cause the 556 is using a dual beam tube. Thats TWO electron gun assemblies in the same bottle. A rare and expensive tube today! |
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| audioquest |
You are absolutely right, but I had the chance to find 2 556's ( vandalized , no tubes and missing parts !!! ) from which I rebuilt one. So I have some spares on hand including a second CRT. These scopes are fun to work with and easy to repair if no essential part broken ( i.e delay line or delay trigger...), they also are very cheap on the second or third hand market , user's manuals can be downloaded free of charge on BAMA and I encourage everyone to put these pieces of electronic art back to service.
Here a pic of the original scope shape. |
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| audioquest |
| Here the guts of the beast as I found it. Never ever destroy an old Tek scope ! :headbash: |
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| jackinnj |
| Tektronix made a spectrum analyzer plug in for that series scope -- |
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| audioquest |
| quote: | Originally posted by jackinnj
Tektronix made a spectrum analyzer plug in for that series scope -- |
I guess something like the 1L... serie, but I never came by one of this plug in. The 1L5 could be interesting for audio measurement. Any experience with this plug in welcome. |
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| Conrad Hoffman |
| I love the old Tek scopes and use a 545B for just about everything. IMO, the 1A7A high gain diff plug-in is an essential tool when looking for ground problems, or anything else that's tiny and under a MHz. There is also a diode recovery time plug-in that's useful if you get a lot of surplus house number diodes. I have a couple of the spectrum analyzer plug-ins, and the audio unit is basically useless. You have to run it really slow to get any resolution and the scope doesn't have persistence. I think you are also stuck with a linear sweep. They were expensive for a while, but prices have fallen. Pretty much useless. The RF units are better, but are also complicated and hard to keep properly tuned up. They all tend to be unreliable, with dirty switches (sealed) and fussy calibration. For audio, you're way better off with a cheap or better sound card. I also have an HP selective voltmeter that's identical to their LF spectrum analyzer, but without the CRT. That's much more useful if you connect it to a chart recorder rather than a scope, but still way less useful than a sound card for SA applications. |
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| audioquest |
| Yes the 1A7 or 1A7A are essential to audio measurement and it would be great to fine one for my 556's. These differential amps have an incredible CMRR of 110dB. For audio measurement I use a HP 3581A with a Tek 7834 storage O'scope. |
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