Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Cursitor Doom Newsgroups: sci.electronics.design Subject: Re: Scope Probes off Ebay Date: Mon, 08 Apr 2024 23:13:42 +0100 Organization: A noiseless patient Spider Lines: 80 Message-ID: <8vq81jpjc7d6gv10cusc53lpo2qsg57rph@4ax.com> References: <4l851jte21egs8mmkqou4proepifknb7v7@4ax.com> <55j51j5n2p9chajruolqrmqs57smippb5t@4ax.com> <7gk51j5homhambnu4inj9dtsnehvh7v64p@4ax.com> <97661jhod6ppmfrn4uf5ji4be6nimb79ru@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Date: Mon, 08 Apr 2024 22:13:44 +0200 (CEST) Injection-Info: dont-email.me; posting-host="bcce0fa8cc37e7ce3d794204d02c965c"; logging-data="3958598"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18HJjYcPDVdnyzvUfsqTIibA10bdt/4tRE=" User-Agent: ForteAgent/8.00.32.1272 Cancel-Lock: sha1:tEPfsOi+1gtFdrFHk/qUeD4fa/I= Bytes: 5130 On Mon, 8 Apr 2024 09:45:03 +0200, Jeroen Belleman wrote: >On 4/8/24 00:11, Cursitor Doom wrote: >> On Sun, 07 Apr 2024 12:08:43 -0700, John Larkin >> wrote: >> >>> On Sun, 07 Apr 2024 18:14:25 +0100, Cursitor Doom >>> wrote: >>> >>>> On Sun, 07 Apr 2024 09:57:13 -0700, John Larkin >>>> wrote: >>>> >>>>> On Sun, 07 Apr 2024 14:51:29 +0100, Cursitor Doom >>>>> wrote: >>>>> >>>>>> I never learn. I bought a used "Agilent 500Mhz probe" off Ebay for 50 >>>>>> quid as the highest bandwidth probe I thought I had was a 150Mhz Tek >>>>>> one. Anyway, I have a large selection of old probes lying around so >>>>>> decided to check to make sure the "Agilent" one was genuine. Not >>>>>> surprisingly it turns out it isn't. I haven't calculated what it's >>>>>> real bandwidth is. I've established it's not as sensitive as the >>>>>> 150Mhz one and that's all I need to know. Whilst I was going through >>>>>> this palarva, I tested a old probe I came across that I've never used >>>>>> before and was amazed at the improvement in signal I got with it. I've >>>>>> just Googled its part number and it turns out it's a 3.5Ghz passive >>>>>> probe! I never even knew I had one so fast. I would never have ordered >>>>>> the "500Mhz" one if I'd known I had this forgotten-about one already. >>>>>> So the fake's going back for a refund and I won't be ordering any >>>>>> more probes from anywhere in the forseeable future. >>>>> >>>>> The HP54006 is a 6 GHz probe, into a 50 ohm scope. >>>>> >>>>> https://www.dropbox.com/s/lxq4ujmkvo755uy/HP54006_probe.zip?dl=0 >>>>> >>>>> They show up on ebay now and then. There's one now, asking $150. >>>>> >>>>> You can make your own with some of those Caddock resistors. The >>>>> Caddocks have some magical recipe. And unlike a fet probe, they are >>>>> hard to damage. I use them to probe 7 ns 1400 volt spikes in my >>>>> Pockels Cell driver. >>>> >>>> Funny you should say that, but the 3.5Ghz probe I mentioned (a Tek >>>> P6056 to be precise) has a fragile resistor assembly in the tip >>>> according to the datasheet and it's easily damaged by rough handling. >>>> I'd be very interested to know what the secret sauce is in the >>>> Caddocks and why they're more robust than whatever Tek used in the >>>> P6056. >>>>> >>>>> And you can do a GHz at least with a 1-cent axial or mini-MELF or 0805 >>>>> resistor on the end of a coax. 450 ohms makes a 10:1 probe. Fast >>>>> circuits are often low impedance circuits and don't mind a 500r or 1K >>>>> load. >>>> >>>> Many years ago when I was somewhat impecunious, I used to improvise >>>> like that, but these days I prefer to just buy whatever I need ready >>>> made. Some of those top-end RF patch cables can be ruinously expensive >>>> to buy ready-made, but what are you gonna do? No matter how good you >>>> are with terminations, you'll never emulate the quality standard of a >>>> properly made, high quality patch lead. When you're as ham-fisted and >>>> half-blind as I am, it's a no-brainer to buy 'em ready-made! >>> >>> Amazon has some crazy cheap coaxial jumpers and SMA and SMB connectors >>> and adapters. All the ones I've got so far have been fine. For bench >>> work of course, not production. >> >> What do you mean by "fine"? How did you go about characterising them >> and what were you looking for specifically? IME you get what you pay >> for and cheap connectors are very seldom worth it. Buy cheap, buy >> twice as they say. > >Not necessarily. I used to buy phase-matched sets of SMA cables >from Huber & Suhner. Then, one day, because H+S did not reply to >a new request for a quotation, I got them from JYEBAO in Taiwan >via a French representative. They were cheaper *and* better. > >Jeroen Belleman They have some interesting stuff for sure. Shame none of their site links work.