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Greetings,
I think I¡¯m coming to the party a little late.
To the individual seeking a vector voltmeter¡
What is the model number of that which you seek?
Regards,
Ken
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I am a "user" rather than a collector, so I do not seek a particular model, just one that can do phase and amplitude at 430 MHz ... so for example a HP 8405A, really, function is more important that brand or model.
There's a few on eBay .. I might risk one of those if nothing cheap turns up on here.
Greetings,
I think I¡¯m coming to the party a little late.
To the individual seeking a vector voltmeter¡
What is the model number of that which you seek?
Regards,
Ken
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What do you consider expensive?
Be careful on EBAY -? make sure probe tips are not broken.
I have several HP VVM along with other test equipment that I will be selling to lighten my inventory after Christmas.
George
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Honestly, the minimum needed to get a workable or at least repairable device.? I basically need to align 2 x 3dB? hybrid couplers at 0/90degree phase ... and then it will probably sit on the shelf until some other excuse to use it arrives .. I appreciate they are lovely, collectable and once very expensive units ... but there are plenty on eBay around the $100 mark that would suit my needs, if shipping was not so expensive to the UK ...
What do you consider expensive?
Be careful on EBAY -? make sure probe tips are not broken.
I have several HP VVM along with other test equipment that I will be selling to lighten my inventory after Christmas.
George
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As noted earlier the probes on the 8405A are the most often abused part of the instrument.? Either some goon has cut or ripped the cables from the instrument, the cables have been pinched, partially cut or alternately damaged or the ends of the probes and/or tips have been broken.
?
Depending upon your requirements you may have to consider the accessories as well.? Much of the 11570A accessory kit is handy for transmission line measurements.
?
It¡¯s interesting that the ePay site is now showing many 8405As with probes and cables attached.? In the past it was almost synonymous that the units were missing their probes and cables but still being listed at cutthroat prices.? I also see one seller listing replacement probe tips which normally are somewhat rare to find.
Christmas time is always the best time to shop on that site.? Everyone is spending their money on Christmas gifts leaving little for the "special" things.
Greg
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At the Newbury rally I came across someone buying up bits of 8405As. He said that he wanted them because he repaired them.? Unfortunatly I didn't manage to get the details.
Had I arrived at the stall I would have bought some of the bits.
Paul G8AQA
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On Mon, Nov 30, 2020 at 06:39 AM, ghnatiuk@... wrote:
What do you consider expensive?
Be careful on EBAY -? make sure probe tips are not broken.
?
I have an 8405, which came with working probes whose tips were worn/broken down.
After looking around for a while I tried ordering a set of replacement tips made by ProbeMaster, intended for their oscilloscope probes. Two sizes are available: 4981ST and 4882MT ("standard" and "micro"). The folks at ProbeMaster told me these have a 0-80 UNF thread, but didn't know if they would fit an 8405 probe.
They do, and they work. They're not identical to the original tips; the insulating bushing is of a larger diameter and it ends up snugging down against the end of the HP probe barrel rather than sliding inside. I don't think that's an issue as this probe position doesn't (I don't think) require a well-characterized transmission line impedance. The thread is a good match for the probe, and the tips seem well-made and sturdy.
At $3.75 each plus shipping, I think they're a very workable alternative to buying new-old-stock HP spares (if you can find 'em) and are more convenient than having to stick an 0-80 screw into a lathe and shave it down to a point.
ProbeMaster also makes a BNC adapter, intended to fit over the end of one of their probes and convert it to a BNC male workalike, using the probe tip as the center pin. These, alas, do not fit the 8405 probe - the diameter of the ground ring at the end of the probe is wrong. It might be possible to make some sort of shim, but I haven't done so.
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Cut probes would be fine for my application, not a problem at all.? My sampling ports are N type,? providing I can get from my sampling ports into the instrument, how it happes is irrelevant to me, providing it is accurate and repeatable.
On Mon, 30 Nov 2020 at 19:22, Greg Muir via <big_sky_explorer= [email protected]> wrote: As noted earlier the probes on the 8405A are the most often abused part of the instrument.? Either some goon has cut or ripped the cables from the instrument, the cables have been pinched, partially cut or alternately damaged or the ends of the probes and/or tips have been broken.
?
Depending upon your requirements you may have to consider the accessories as well.? Much of the 11570A accessory kit is handy for transmission line measurements.
?
It¡¯s interesting that the ePay site is now showing many 8405As with probes and cables attached.? In the past it was almost synonymous that the units were missing their probes and cables but still being listed at cutthroat prices.? I also see one seller listing replacement probe tips which normally are somewhat rare to find.
Christmas time is always the best time to shop on that site.? Everyone is spending their money on Christmas gifts leaving little for the "special" things.
Greg
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Trimming down my collection due to an out-of-state move.
Please contact me directly if interested. I am in the US.?
Thank you,
Wolfgang, KI7PFX
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You need the probes to be intact on the 8405A as the probe heads contain the magic circuitry that makes the whole vector voltmeter work. An 8405A without probes is essentially useless.
There are accessories for the probes that convert to BNC (10218A) or a 50ohm tee with N connectors (11536A).
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The accessory kit for the 8508A vector voltmeter is compatible with the 8405A probes. Along with various probe tip adapters it also contains replacement probe tips and a miniature nut driver to install those tips.
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Ah yes, you are right Steve, they have the sampling sub-harmonic mixers in the probes themselves , thank you!
On Wed, 2 Dec 2020 at 13:18, Stephen Bell < s.r.bell@...> wrote: You need the probes to be intact on the 8405A as the probe heads contain the magic circuitry that makes the whole vector voltmeter work. An 8405A without probes is essentially useless.
There are accessories for the probes that convert to BNC (10218A) or a 50ohm tee with N connectors (11536A).
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Haaa I was thinking the same thing!
-Dave
toggle quoted message
Show quoted text
On 12/2/20 1:13 PM, Robin Szemeti wrote: Wow ... that is so nice.? The moment I opened that photo, my wallet made a run for the door ...
On Wed, 2 Dec 2020 at 17:36, Greg Muir via groups.io <> <big_sky_explorer@... <mailto:[email protected]>> wrote:
A kit made up of accessories that were acquired new from RF parts
distributors and also over time before eBay sellers figured out how
much excessive money they could extract from buyers.? Total cost
around $200.
/g/HP-Agilent-Keysight-equipment/photo/68476/1?p=Name,,8405a,20,1,0,0
Greg
--
Dave McGuire, AK4HZ
New Kensington, PA
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This may or may not be relevant but the probe tips for the 85024A active probe appear to be 1-72 UNF by eye and Chinese vernier caliper. AF on the nut section is 3/32" from the nanual and there are two different types with different tip diameters. Keysight part numbers are 85024-60015 and 85024-60016 which are still listed as active on the Keysight website. Of course the cost will be eyewatering ......
Dave
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FYI¡ i listed a 85024a a bit ago that is complete and working in the box.? ?It includes 3 non working 85024a's, 20 or so new tips (like what is shown here).? 3 ics untested? and more.? ?$1450 for everything SHIPPED CONUS¡ non-US additional
If not sold as group package soon,? i will sell tips separately (real original hp)?
For pictures and more details ask off group.?
Located¡ Ft.? Mill,? SC ,? USA
Payment¡? check on us bank,? US postal mo., Western Union,? bank xfer,? ?NO PAYPAL!?
Pete wa2odo
On Wed, Dec 2, 2020, 2:22 PM Dave G8KHU < david@...> wrote: This may or may not be relevant but the probe tips for the 85024A active probe appear to be 1-72 UNF by eye and Chinese vernier caliper. AF on the nut section is 3/32" from the nanual and there are two different types with different tip diameters. Keysight part numbers are 85024-60015 and 85024-60016 which are still listed as active on the Keysight website. Of course the cost will be eyewatering ......
Dave
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Dave McGuire