- 1. [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: Dan Sawyer <dansawyer@earthlink.net>
- Date: Thu, 08 Dec 2005 22:08:02 -0800
- All, I have an 8405a with a bad probe. The unit makes it through most of the calibration until the noise cancellation step. One board works and comes in at less then 5 mv. However one shows a 1V peak
- /archives//html/Amps/2005-12/msg00100.html (6,605 bytes)
- 2. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: Steve Thompson <g8gsq@eltac.co.uk>
- Date: Fri, 09 Dec 2005 07:37:17 +0000
- Usually it's blown from overload - the four diodes in the sampling gate and/or the p-channel fet go. There's a guy on ebay sells replacement kits. I haven't got round to repairing the one I have, but
- /archives//html/Amps/2005-12/msg00101.html (7,545 bytes)
- 3. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
- Date: Fri, 9 Dec 2005 13:34:13 +0100 (CET)
- like wave. This probe actually works, however due to the fault it has a phase frequency error< Have you checked the four Schottky diodes in the sampler? I've had funny answers like yours when one of
- /archives//html/Amps/2005-12/msg00102.html (7,210 bytes)
- 4. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: Dan Sawyer <dansawyer@earthlink.net>
- Date: Fri, 09 Dec 2005 06:59:26 -0800
- Peter - Thank you. Is there a simple way to match them? I have an old Tek curve tracer. Will a simple visual match work? 73 Dan - kb0qil _______________________________________________ Amps mailing l
- /archives//html/Amps/2005-12/msg00103.html (8,146 bytes)
- 5. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: Dan Sawyer <dansawyer@earthlink.net>
- Date: Fri, 09 Dec 2005 07:11:47 -0800
- Steve, I have a cross match for HP2800 and HP2835 to NTE parts 112 and 484, they are available locally. What characteristics should I look for? In this circuit as long as they match will they work in
- /archives//html/Amps/2005-12/msg00104.html (9,152 bytes)
- 6. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: "Carcia, Francis A HS" <francis.carcia@hs.utc.com>
- Date: Fri, 9 Dec 2005 10:37:17 -0500
- 1N5711 is a good choice they sell for about a buck each. 1N7512 will be a bit more sensitive. Matched quads will be quire rare and who knows if it really matters. --Original Message-- From: amps-boun
- /archives//html/Amps/2005-12/msg00105.html (8,994 bytes)
- 7. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: Steve Thompson <g8gsq@eltac.co.uk>
- Date: Fri, 09 Dec 2005 17:09:53 +0000
- I think any small shottky diode will work in the circuit. Without studying the manual, I'm not sure which characteristics matter most, but at I doubt there's any need for precision matching, if you b
- /archives//html/Amps/2005-12/msg00106.html (8,561 bytes)
- 8. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: "Alex Eban" <alexeban@bezeqint.net>
- Date: Fri, 9 Dec 2005 19:49:22 +0200
- ....that's true! For the most part, Shottky diodes are much more uniform that the silicon junction type. If you want to look for some RF relevant fearture, check for the forward voltage drop in a reg
- /archives//html/Amps/2005-12/msg00107.html (8,215 bytes)
- 9. Re: [Amps] help diagnosing a bad 8450a probe ? (score: 1)
- Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
- Date: Fri, 9 Dec 2005 20:40:17 +0100 (CET)
- As Steve says, getting diodes from the same batch will probably do it. It's just that matched diodes come from about the same place on the wafer: it is not uncommon to get a variation across a wafer
- /archives//html/Amps/2005-12/msg00108.html (8,516 bytes)
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