Kikusui 7101A, is it close enough to an analog scope? - Page 1
Forum section: electronics / testgear

author: thomsmith69
author_rank: Newbie
timestamp: February 24, 2015, 12:23:57 am
content: Ladies and gentlemen,I submit to you the following question;Is a Kikusui COM7101A close enough to an analog scope that I shouldn't go out and buy a modestly priced Tektronix 2225?I know that Dave is an advocate of people who are starting out or getting back into electronics, getting their hands on a decent analog scope. I recently purchased a Kikusui 7101A at auction and got it back on its feet. After working with it for a bit, it feels very analog to me, apart from a lack of knobs and levers with markings, just buttons and rotary encoders.Prior to purchasing the Kikusui I had purchased a Leader 8101 on eBay that suffered an unfortunate demise when the delivery truck driver decided to throw the package onto the porch rather than take the few extra steps to place it there. It still works but the display is so out of whack it is impossible to use. Haven't found somewhere to get a replacement.What is the general feeling on this? Should I start working on a gear collection like Dave's or just keep working with the Kikusui. The Tektronix is selling for 200 CDN. I paid 85 CDN for the Kikusui.Thanks in advance for any input you can provide.Thom

author: Fsck
author_rank: Super Contributor
timestamp: February 24, 2015, 12:34:02 am
content: the manual says it's a DSO with a CRT.do you happen to know why you want a CRO in addition to a DSO?

author: thomsmith69
author_rank: Newbie
timestamp: February 24, 2015, 12:41:53 am
content: That's what I'm here to find out.Near as I can tell, the DSO portion of the Kikusui is very limited and that's fine with me. My interest is getting my feet wet again and learning the basics before deciding if I need to step up to something more advanced.The price was right on the Kikusui and as I had struck out with the Leader, it made a good second choice.I am not Tek-savvy and was just looking for a bit of advice on whether there might be an advantage of having a pure CRO in addition to the CRT powered DSO.

author: tautech
author_rank: Super Contributor
timestamp: February 24, 2015, 12:48:10 am
content: Welcome to the forum.Looks like a nice scope and you got it for a good price IMO.Nice to see it has 400V rated BNC inputs.Not sure the DSO functionality will affect its usage for normal work, but I don't think so.But the storage function you may find very usefull.Did you find this old thread?https://www.eevblog.com/forum/testgear/kikusui-com7101a/Manual:http://www.kikusui.co.jp/kiku_manuals/C/COM7000A_E2.pdfThe only thing that worries me is can you find a Service manual?At least with the Tek they are available.

author: macboy
author_rank: Super Contributor
timestamp: February 24, 2015, 12:54:47 am
content: Look in the instruction manual under Features, points 17 and 18. The real time sampling is limited to 50 MSps, which they state (generously) is good up to 14 MHz signals. It can use equivalent time sampling (oversampling) on repetitive signals in order to gradually build up a image of the waveform with an equivalent sampling rate of 5 GSps. This allows viewing repetitive signals up to 100 MHz.The 50 MSps is the main limiting feature. If you are only looking at repetitive signals, then this is not a big deal except for the long amount of time to build up the waveform using equivalent time sampling. With an analog scope, you instantly see the waveform. With these slow older digital scopes, it can be more difficult to see a noisy waveform, or one that is oscillating. On an analog scope, the noise or oscillations can be seen as a fuzzy (not sharp) trace. On a digital scope, esp. these older ones that depend so much on equivalent time sampling, the noise can end up averaged out and hardly appear at all.

author: dom0
author_rank: Super Contributor
timestamp: February 24, 2015, 01:05:26 am
content: I don't see any general benefit of a classic analog scope over a DSO. There are of course specific benefits of specific devices, so for example you have Tek 7000 series with their boatloads of different amplifiers, including very sensitive ones etc. that might be more useful than a DSO with 2 mV/DIV — if you need it (see below) — and still cheap.Or, for example, the great majority of DSOs - and all faster ones - have a fan which can be annoying to various degrees. So it might be an option to buy a cheap CRO to have something to work with if the fan annoys you again, or if you don't want the fan to make noise because you want to hear something (like inductor noise of switching regulators and stuff like that).Also (as I keep sayingold DSO tech isold- it's pretty shitty compared with even the cheapest Rigol or Hantek scope, all of which have larger memories and much greater single shot bandwidth. Only the very high end DSOs from the 90s can still compete with cheap and midrange DSOs of today.Quote from: thomsmith69 on February 24, 2015, 12:23:57 amWell, honestly, if you want to actuallydoelectronics stuff I'd advocate against trying to collect random gear just because it appeared in the background of some video of some guy on some video site - this still holds true if some guy is Dave. Instead, think about what kind of gearyoucan put to good use - what is useful toyou? Knowing that is much more important than seeing something in a video and thinking you can't build electronics stuff of kind X without that thing.There are some things that are common to electronics tinkerers, like a multimeter or a scope – but I really wouldn't prescribe any specific kind of either. Buy what is useful to you with the money you would like to spend ; everything else will probably just collect dust on some shelf in your home.Usually, if you need something, you'll know it, although there are exceptions, as to every rule there are, so you might need/want something without knowing that yet.

author: Fsck
author_rank: Super Contributor
timestamp: February 24, 2015, 01:07:28 am
content: probably should've said that 200$ for a 2225 is too much when a ds1054z is 400.

author: EEVblog
author_rank: Unknown
timestamp: February 24, 2015, 01:08:35 am
content: Quote from: thomsmith69 on February 24, 2015, 12:23:57 amIf you want a real analog, then yes. The COM7101A is digital storage only scope.

author: EEVblog
author_rank: Unknown
timestamp: February 24, 2015, 01:11:10 am
content: Quote from: dom0 on February 24, 2015, 01:05:26 amOver a modern one, there isn't.So many people take my advice about about analog scopes out of context.If you have no scope, then an analog scope is better than a toy $50 USB or handheld Nano thing for a beginner.Otherwise, get a real modern bench DSO.

author: dom0
author_rank: Super Contributor
timestamp: February 24, 2015, 01:14:16 am
content: Quote from: EEVblog on February 24, 2015, 01:11:10 amI couldn't agree more

author: thomsmith69
author_rank: Newbie
timestamp: February 24, 2015, 01:19:07 am
content: Dave, thank you for clarifying that. I've been pulling my hair out about whether I should be going analog or pulling the pin on something like the Rigol DS1054Z.Thank you all for your input. I had some great reply written, but I missed the checkbox that said leave me logged in and just as I went to post, I got logged out.I certainly have the budget, if I don't buy the 2225, to spring for the Rigol.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 24, 2015, 01:23:54 am
content: I would suggest analog (along the lines of a Tek 2xxx series) if you're trying to save bucks (they can be had for ~$100 in reasonable condition), but if you can afford a good instrument, I would recommend by all means a Rigol or whatever.Tim

author: thomsmith69
author_rank: Newbie
timestamp: February 24, 2015, 01:43:56 am
content: I did a little digging and there is a dealer close to where I am that has the Rigol DS1054Z for 399 CDN.I think my plan will be to save a few more dollars and order myself one of them. In the meatime, I'll have some fun playing with the Kikusui.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 24, 2015, 07:33:28 am
content: Quote from: EEVblog on February 24, 2015, 01:11:10 amI couldn't agree more. For several years I put up with an old 100 MHz dual channel CRO, it had a couple of annoying faults, one channel had intermittently varying gain and the triggering was often poor at best. The power supply finally failed.The old scope was replaced by a Rigol DS1054Z, as yet un-hacked. I am a hobby user of home built RF projects up to mostly 30 MHz and associated audio and control circuitry, as part of my ham radio station. There is nothing the old CRO could do that in my opinion isn't done better and more easily with the Rigol. Having four channels is very useful for basic control timing measurements.I added a pair of 50 Ohm BNC through terminators as the Rigol doesn't have built in termination.