I bought the Leo Bodnar device because it could do 10MHz for my 'scope and Agilent E4420B oscillator but also the 96kHz for my dScopeIII audio analyser. I'm not convinced that it has been of any benefit, but I wanted to eliminate possible problems before embarking on a lot of lab work.
I fear you are right about through-terminations, but you so often are charged for the name:
https://uk.farnell.com/keysight-technol ... dp/2853354
£67.35 + 20% VAT for a triax cap? You're 'avin' a larf!
TEK 485
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Use tags for the type of equipment your topic is about. Include the "repairs" tag, too, when appropriate. If a new tag is needed, request one in the TEAdministration forum.
Use tags for the type of equipment your topic is about. Include the "repairs" tag, too, when appropriate. If a new tag is needed, request one in the TEAdministration forum.
Re: TEK 485
Triax is something most of us don't come across, and to produce it is going to be taking a risk. There were one or two odd BNC types.
What's the difference between a 10dB attenuator you've put together faithfully following the equations in the book, and a for real 10dB 20W attenuator good from DC to 5GHz? The beautifully engineered radiator gives something away, as do the seriously well constructed N type connectors, then there's the warning about the beryllia content. It's not altogether a black art to produce such a thing, but it's near to it.
HPAK, Le Croy, R&S, et al, almost certainly don't make probes, attenuators and cables, although they'll have people fully clued up on these things. PMK, JFW and others will have honed their processes. Of course they would never disclose who their OEM customers were.
What's the difference between a 10dB attenuator you've put together faithfully following the equations in the book, and a for real 10dB 20W attenuator good from DC to 5GHz? The beautifully engineered radiator gives something away, as do the seriously well constructed N type connectors, then there's the warning about the beryllia content. It's not altogether a black art to produce such a thing, but it's near to it.
HPAK, Le Croy, R&S, et al, almost certainly don't make probes, attenuators and cables, although they'll have people fully clued up on these things. PMK, JFW and others will have honed their processes. Of course they would never disclose who their OEM customers were.
Re: TEK 485
Agreed, the sales of triax parts will be small. But £80.82 for a triax cap is insulting the customer. A few years ago, they were £15 each, expensive, but reasonable in the light of needing the machine that mills out the lug holes to be set for three rather than two. Other than that, those caps are identical to the BNC caps seen earlier in this thread. I appreciate that making something resistive from DC to 5GHz is going to be close to a black art and there you pay for the knowledge to design it and the machining to fabricate it accurately; you're paying for years of expensively won knowledge. But triax is for electrometers and anything >1kHz is very fast, so the only real issues are material choice and manufacturing cleanliness. I have learned from experience that it is cheaper and better to build a custom electrometer into the test cell than to fit a triax connector. It won't hum and the shunt capacitance across the input of the electrometer is essentially zero, significantly reducing noise gain.
Re: TEK 485
I suppose so, but if you are in the world of £20,000 femtoammeters, everything is going to be expensive, including things like carrying cases. Most buyers will not be spending their own money anyway.
I thought Aliexpress might be worth a look for something like that. There are not many triax items on there and they are surprisingly dear.
I thought Aliexpress might be worth a look for something like that. There are not many triax items on there and they are surprisingly dear.
Re: TEK 485
Gulp! Have they shot up in price? List price of a Keithley 6517B is now £11,300 + VAT. Wildly expensive, but not (yet) £20,000. So I looked up a Keithley 6430; £26,300. Yikes! I bought one of those for work a few years ago. The main difference between the two instruments is that the input leakage current of a 6517 is about 3fA and can take about a day to settle whereas the 6430 is about 1fA and settles quite quickly.
It really shouldn't make any difference about whether it's your own money. You owe it to your employer not to squander resources. I always haggled on price when buying kit for work. 20% discount off list price was reasonably easily achieved, but I aimed for significantly more. And often got it. Because I always haggled and never asked for stuff I didn't need, I never had any trouble getting approval to buy stuff.
Re: TEK 485
It was under the part about the Triax cap on the Farnell link you gave. Associated Poducts. I'm sure it gave two which were £19 grand and over £20 grand. I've just looked and they offer two at £16 grand and £19 grand. I didn't have my computer specs so maybe they were USD prices or they may have been different models. Still it's a lot of brass.
Further down the page there are Similar Products. The prices will make your eyes water. A spring hook adapter for £120. A Triax plug BNC jack adapter, £1,100. Maybe I'm missing something, but it isn't obvious to me why there should be a material difference between a £120 spring hook adapter and a Testec one costing two or three quid. The Agilent probe may be non-standard and so generic witch's hats won't fit, and they only make them in small quantities, and so on. Agilent almost certainly don't make probes anyway.
Official spares from the likes of HP and Tek were always expensive, even though they might be run-of-the-mill ICs and other common parts. I thought it was because the overhead of dealing in these items was high, They were obliged to list spares, but they really didn't want to, they could charge what they liked, and if it discouraged the customer, so much the better.
In most large companies and organisations such as university departments, budgets are inflexible and have to be spent. If a manager underspends significantly, he's in serious trouble. Slight overspending is expected. Serious overspending is nowhere near as bad as serious underspending.
I had a manager who had something like £30 grand of equipment budget to spend, and he asked if I could think of anything to help him out. So I ordered two top end UNIX workstations with all the options; full complement of memory, biggest hard drives, top end graphics, 21" monitors. All to make them use up the budget. The IT dept kept an eye on these things and their eyes popped out. They said we couldn't possibly need this. I told them to go and tell Sid that they weren't going to let him spend his equipment budget. The workstations came. We did use UNIX workstations, but we didn't need anything like that. It was funny money in that they were made by a different part of the company, but even so. Sid was grateful I'd got him out of a hole.
Further down the page there are Similar Products. The prices will make your eyes water. A spring hook adapter for £120. A Triax plug BNC jack adapter, £1,100. Maybe I'm missing something, but it isn't obvious to me why there should be a material difference between a £120 spring hook adapter and a Testec one costing two or three quid. The Agilent probe may be non-standard and so generic witch's hats won't fit, and they only make them in small quantities, and so on. Agilent almost certainly don't make probes anyway.
Official spares from the likes of HP and Tek were always expensive, even though they might be run-of-the-mill ICs and other common parts. I thought it was because the overhead of dealing in these items was high, They were obliged to list spares, but they really didn't want to, they could charge what they liked, and if it discouraged the customer, so much the better.
In most large companies and organisations such as university departments, budgets are inflexible and have to be spent. If a manager underspends significantly, he's in serious trouble. Slight overspending is expected. Serious overspending is nowhere near as bad as serious underspending.
I had a manager who had something like £30 grand of equipment budget to spend, and he asked if I could think of anything to help him out. So I ordered two top end UNIX workstations with all the options; full complement of memory, biggest hard drives, top end graphics, 21" monitors. All to make them use up the budget. The IT dept kept an eye on these things and their eyes popped out. They said we couldn't possibly need this. I told them to go and tell Sid that they weren't going to let him spend his equipment budget. The workstations came. We did use UNIX workstations, but we didn't need anything like that. It was funny money in that they were made by a different part of the company, but even so. Sid was grateful I'd got him out of a hole.
Re: TEK 485
As you say, a lot of brass. I borrowed an Agilent electrometer for evaluation when I was looking to buy an electrometer for myself. The Agilent was much nicer to use. Hugely nicer. But... It didn't do the essential thing of having low and stable input leakage current. So I bought the Keithley despite its appalling ergonomics, and haggled hard on price.
Perzackly on the accessories.
I am well aware of the underspend issue. As our American friends would say, "That's no way to run a rail road!" I made sure our section had the test gear we needed to do the job we had to do. What the underspend issue says is that the management running the company is more concerned with protecting their importance than in getting the job done. I often had the, "We have some money that needs spending, can you help?" plea. I tended to keep in the back of my mind some "Nice to have" items that could be sprung on those occassions. I think the 6430 might have been one of those.
Changing the subject entirely, our printer needed a new toner cartridge. I don't know if I broke it or if it was ready-broken, but there was an extremely weak sticky out bit that lifted the cover away from the photo-sensitive roller that had come off. A close look revealed that plastic had been removed at the point where there was maximum leverage, saving, oooh, 0.01p on material cost. I filled the cavity with Araldite, cured it overnight in the airing cupboard, and carefully drilled a 1.5mm hole into the plastic/Araldite the next day. After that, I turned a skewer to 3mm diameter, then put a 1.5mm spigot on one end and Araldited it into the 1.5mm hole. Today was the moment of truth. Rather boring, really. It all slipped into printer as it should and now works. A satisfying repair, even though it shouldn't have been necessary.
Perzackly on the accessories.
I am well aware of the underspend issue. As our American friends would say, "That's no way to run a rail road!" I made sure our section had the test gear we needed to do the job we had to do. What the underspend issue says is that the management running the company is more concerned with protecting their importance than in getting the job done. I often had the, "We have some money that needs spending, can you help?" plea. I tended to keep in the back of my mind some "Nice to have" items that could be sprung on those occassions. I think the 6430 might have been one of those.
Changing the subject entirely, our printer needed a new toner cartridge. I don't know if I broke it or if it was ready-broken, but there was an extremely weak sticky out bit that lifted the cover away from the photo-sensitive roller that had come off. A close look revealed that plastic had been removed at the point where there was maximum leverage, saving, oooh, 0.01p on material cost. I filled the cavity with Araldite, cured it overnight in the airing cupboard, and carefully drilled a 1.5mm hole into the plastic/Araldite the next day. After that, I turned a skewer to 3mm diameter, then put a 1.5mm spigot on one end and Araldited it into the 1.5mm hole. Today was the moment of truth. Rather boring, really. It all slipped into printer as it should and now works. A satisfying repair, even though it shouldn't have been necessary.
Re: TEK 485
I can see half the point. There is a limited amount of money which could be used here or there. If you say you want to use it then they don't get it. If you don't use it then they could (and arguable should) have used it. So a "penalty" isn't unreasonable.EC8010 wrote: ↑Fri Dec 12, 2025 7:06 pm I am well aware of the underspend issue. As our American friends would say, "That's no way to run a rail road!" I made sure our section had the test gear we needed to do the job we had to do. What the underspend issue says is that the management running the company is more concerned with protecting their importance than in getting the job done. I often had the, "We have some money that needs spending, can you help?" plea. I tended to keep in the back of my mind some "Nice to have" items that could be sprung on those occassions. I think the 6430 might have been one of those.
ISTR hearing of a company who wanted an X but it wouldn't be available until their next financial year. Ooops. The workaround was to make a faulty shipment before the end of the FY, and correct the mistake in the next FY. Can't remember whether HP was on the sending or receiving part of that; probably sending.
Re: TEK 485
The underspend thing, which I first came across when the professor of microbiology explained it to us in the 70s, always intrigued me. No way could you fold the underspend into next year's budget. Underspend was a crime. A year back I bumped into an accountant I worked with 40 years back and asked him about it. He said there was no accounting reason. It was a cultural thing.
For the most part, it seemed to work fairly well. At the start of the year, negotiating down the price of acquisitions would get you a pat on the back. Towards the end of the year, you might find a few new PCs appeared or you had to struggle on with the three year old ones a bit longer to balance things out. Sid (not his real name) was a case in point. I never had much time for him.
The worst case I came across was a marketing manager, who was notably obsessed with planning. About 4 months before the end of year, they announced that there was $250,000 to be spent. Something had fallen through and there was no contingency plan. A couple of high end workstations weren't going to paper over this one. They were bending the rules to buy OTT TE for R&D. It was explained to them that there were other companies out there, where their contribution would be even more valued, and they would undoubtedly feel more fulfilled.
Dunno about the printer cartridge. The business seems to have turned into a calculated racket to fleece the customer, all in the interests of assuring a totally satisfactory printing experience of course. They sell the printer on the Gillette razor model. Sell the device at a loss with low capacity cartridge and reap the rewards of people then buying full capacity replacement cartridges costing as much as the printer. Entrepreneurs have appeared selling compatible cartridges and toner refill bottles with instructions. Public spirited folk have produced various inventive solutions to implement their different idea of a totally satisfactory printing experience. It's cheap and it works. These may involve hardware and firmware mods.
If you've managed to avoid being ripped off, good for you.
For the most part, it seemed to work fairly well. At the start of the year, negotiating down the price of acquisitions would get you a pat on the back. Towards the end of the year, you might find a few new PCs appeared or you had to struggle on with the three year old ones a bit longer to balance things out. Sid (not his real name) was a case in point. I never had much time for him.
The worst case I came across was a marketing manager, who was notably obsessed with planning. About 4 months before the end of year, they announced that there was $250,000 to be spent. Something had fallen through and there was no contingency plan. A couple of high end workstations weren't going to paper over this one. They were bending the rules to buy OTT TE for R&D. It was explained to them that there were other companies out there, where their contribution would be even more valued, and they would undoubtedly feel more fulfilled.
Dunno about the printer cartridge. The business seems to have turned into a calculated racket to fleece the customer, all in the interests of assuring a totally satisfactory printing experience of course. They sell the printer on the Gillette razor model. Sell the device at a loss with low capacity cartridge and reap the rewards of people then buying full capacity replacement cartridges costing as much as the printer. Entrepreneurs have appeared selling compatible cartridges and toner refill bottles with instructions. Public spirited folk have produced various inventive solutions to implement their different idea of a totally satisfactory printing experience. It's cheap and it works. These may involve hardware and firmware mods.
If you've managed to avoid being ripped off, good for you.
Re: TEK 485
Yes, it's cultural. And faulty logic; "Look how busy that department is, they're always needing more test equipment. But that other department can't be doing much because we never hear from them at budget meetings; perhaps that's where we should look for redundancies." I kid you not, I've seen that. It was dressed up in more words and circumlocution, but that was what it boiled down to. Make a lot of noise + spend it noisily = success.
I think the best I can claim is that we didn't have to buy yet another toner cartridge just because a tiny little badly designed bit broke on an unused cartridge. I deem it a win because it was a successful mend.