WTB:tektronix 2225 or similar 2 channel 20-50MHZ Analogue CRO for under $100 AUD - Page 1
Forum section: electronics / general

author: auxie22
author_rank: Contributor
timestamp: April 01, 2014, 01:19:16 pm
content: Hi I am currently studying Electronics in Adelaide, Australia and they have tek 2225 scopes which I quite like. I have recently bought a Rigol DS-1102E but I want more resolution at low voltages. I know analogue CRO's are generally better at this as they are not limited by sampling rates etc. Can someone please recommend or advise of somewhere where I can get something like this for under $100? I don't mind if it is not calibrated or non functional.Thanks in advance guysJules.

author: echen1024
author_rank: Super Contributor
timestamp: April 01, 2014, 11:37:14 pm
content: eBay.

author: TVman
author_rank: Frequent Contributor
timestamp: April 03, 2014, 03:24:49 am
content: Look on ebay....http://www.ebay.com/If you can't find one:https://www.eevblog.com/forum/blog/eevblog-498-how-to-get-a-$50-oscilloscope-on-ebay/GD luck!

author: EEVblog
author_rank: Unknown
timestamp: April 03, 2014, 03:26:43 am
content: Set up email alerts on ebay and gumtree.Very occasionally pop up on Graysonline too.

author: auxie22
author_rank: Contributor
timestamp: April 05, 2014, 12:40:05 am
content: thanks all have heaps of saved searches now... been bidding on some got outbid on a few too... are Kenwood a good brand out of interest? I'm not a fan of their car audio but I wasn't sure if their CRO's were decent or not.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 05, 2014, 12:55:38 am
content: I thought the 2225 series were less fixable than some of the other older models. I may be misremembering but I seem to recall that bit of info while I searched for a cheap old scope.I'm not sure about Kenwood.

author: Shock
author_rank: Super Contributor
timestamp: April 05, 2014, 01:33:31 am
content: Quote from: auxie22 on April 05, 2014, 12:40:05 amKenwood made some decent ones and also some not so decent ones.Watch for a couple of weeks and see what comes up, put a wanted advert in gumtree perhaps.If nothing much comes up just grab something that fits the job. Beggars can't be choosers and you would be lucky to pickup a really nice Tek here for $100.

author: David Hess
author_rank: Super Contributor
timestamp: April 05, 2014, 06:42:09 am
content: Quote from: GiskardReventlov on April 05, 2014, 12:55:38 amThe 2225 is distinct from the other 22xx series oscilloscopes and uses fewer custom ICs than the faster 22xx models so at least from that perspective it should be easier to maintain. CA3102 transistor arrays are used in the vertical amplifier chain for instance. It is the first one I think of when someone mentions audio applications although I am not convinced the extra sensitivity is significant.I suspect the 2225 is closely related to the 2210 and 2211 which are combination analog and digital storage oscilloscopes that share the same bandwidth, high vertical sensitivity, and input capacitance but I only have schematics for the 2225.The only 22xx oscilloscopes I would actively avoid are the 2213 and 2215 which are known to be problematical.

author: auxie22
author_rank: Contributor
timestamp: April 05, 2014, 09:37:23 am
content: Thanks for the info David! when it comes to the old tek's i'll stick to the 2225 might save up a bit longer and see if I can get one "buy it now" but I'm not spending $250+ on a 20 year old CRO as Dave said on his video "they've gotta be dreamin'!" maximum including postage will probably be around $200. I have seen some nice hitachi's around too for cheap so I might even look at one of those. Again thanks guys much appreciated.Jules

author: David Hess
author_rank: Super Contributor
timestamp: April 05, 2014, 03:09:47 pm
content: Quote from: auxie22 on April 05, 2014, 09:37:23 amI would not spend that much either. At least in the US with patience I would expect to find a 2225 for $50 or less and I see several completed Ebay auctions in that range and at that price, one could buy more than one as a source of parts if necessary.It helps if you are confident in being able to repair and refurbish it though. It took me a couple months and a couple of other oscilloscopes to track down and repair a problem in a 2230 that I bought for $80.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 05, 2014, 07:38:06 pm
content: Quote from: David Hess on April 05, 2014, 06:42:09 amQuotePointers to anything regarding the 2213/2215 having known problems would be useful here. Sure the usual tube issues, but that's verifiable before buying.A quote from this article:"Stay away from the 2205, 2225 they were made in the orient, and have serious quality issues as used scopes."http://www.ebay.com/gds/Buying-an-Oscilloscope-on-ebay-/10000000001568756/g.html

author: grumpydoc
author_rank: Super Contributor
timestamp: April 05, 2014, 10:14:46 pm
content: Personally I think that article is overly down on some members of the 22xx 'scopes.Iwouldbe careful with some of the early 2213's and 2215's - these have a couple of design problems. Firstly the power supplies can be troublesome - there was a field mod to fit a pre-regulator on the early ones (which invariably and quickly developed audibly noisy PSUs), Tek then redesigned the power supply. There was also a problem with the CRT heater being run at about 8V rather than the tube design voltage which was 6.3V and that led to early CRT failures in some 'scopes.Again there was a field mod which involved removing one turn from the heater winding and later a redesigned transformer. Also it is possible to use a CRT from a 465 in some of these 'scopes (Sphere -http://www.sphere.bc.cahas some notes on this)I wouldn't say avoid the older 'scopes completely but if you can get the "A" version of these 'scopes then do so, not only will they be newer but likely to be more reliable over time.One might argue that any of these 'scope that has survived is either very obviously going to be in trouble or will probably be OK.The purely analogue 22xx series (2213, 2215, 2225, 2235) have essentially no custom parts, or parts which couldn't be substituted with modern equivalents. The digital 'scopes (2236, 224x, 2252) are rather different anddohave a lot of custom stuff so you should probably only buy one if fully working (or you like collecting old 'scopes and repairing them).

author: David Hess
author_rank: Super Contributor
timestamp: April 06, 2014, 01:34:05 am
content: grumpydoc's post covers the CRT heater voltage and power supply issues in the 2213 and 2215.I forget which but one of the first Tektronix oscilloscopes I repaired was a 2213 or 2215 for a friend in which the load resistors in the vertical CRT amplifier had failed. Tektronix used two resistors in series on each side to get the necessary power rating and low capacitance but later models used three in series on each side. Diagnosis and repairs were easy although I had to recalibrate the vertical response which was an interesting exercise in itself without a calibrated signal source. Since that time I have bought and refurbished a PG506 which makes vertical calibration much easier.What struck me most is that the vertical and horizontal range switches were not the cam operated ones used in previous Tektronix instruments and the rest of the 22xx series of oscilloscopes but some form of rotary wafer switch and they were both mechanically questionable and difficult or impossible to service unlike the cam switches. The 2213A and 2215A which replaced the 2213 and 2215 use the more reliable cam switches.I believe the 2213 and 2215 really should be considered their own series separate from the rest of the 22xx oscilloscopes although there are several groupings there. They are the only ones with 30pF inputs and they use a very different attenuator and vertical signal chain design unlike the 2235 series which includes the 2213A, 2215A, and 2232.

author: linux-works
author_rank: Super Contributor
timestamp: April 08, 2014, 04:24:47 am
content: I bought my 2225 around 2 or 3 yrs ago, back when they were still somewhat reasonable in price ($80 or so for mine). now, they tend to be $200 and upwards. insane, but this is the dave-dot effect in operation

author: auxie22
author_rank: Contributor
timestamp: April 08, 2014, 07:32:24 am
content: i'll definitely be waiting for some "for parts or not working" and see if I can get a couple of units cheap. The other thing is, I have seen 200+ just for postage. Is it me or is that absolutely ridiculous? I have even seen some non functional cro's with that sort of postage.

author: David Hess
author_rank: Super Contributor
timestamp: April 08, 2014, 08:28:27 am
content: I do not know how much excitement you want but the 2210 and 2211 are the same as the 2225 with added DSO capability so they are both an analog and digital oscilloscope. They are not as common and usually more expensive than the 2225 but maybe you will get lucky.The 2214 is similar to the 2225 but slower, 20 MHz, and also a DSO and 4 channels as well but rarer yet.

author: auxie22
author_rank: Contributor
timestamp: April 08, 2014, 09:07:53 am
content: heh might even end up getting an hitachi or kik depending on price but i'll keep looking for tek cro's too

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 08, 2014, 03:44:19 pm
content: Quote from: auxie22 on April 08, 2014, 07:32:24 amIn another thread about ebay, someone mentioned that some sellers avoid taxes by low price with high shipping. But that only applies in certain countries.

author: David Hess
author_rank: Super Contributor
timestamp: April 08, 2014, 03:49:31 pm
content: Quote from: GiskardReventlov on April 08, 2014, 03:44:19 pmThey also did this to lower the Ebay fees but now Ebay charges for the cost of shipping as well.