Test Equipment Anonymous

I scrapped the Solartron Varipak power supply last night; it was bought primarily for its 20H HT choke. Which turned out in this Varipak to be made by Woden (I've seen some terrible transformers made by them, so that was worrying). But I've just measured the choke and it's surprisingly good. You'd e...

Yes, Forum Stores was indeed the Nissen hut by the school. It later moved back to the university and I bought a 59" steel rule from there (£1), and also a Tek 545 oscilloscope for £10, on its trolley.

Wow! That power supply is (as the seller honestly declares) "in bad shape". Whatever happened to it to cause that? Parachute failed to open? I didn't notice that there were piles that discriminated between quality at Crowdhill. I assumed (from equipment age) that it was all iffy. There use...

I've just scrapped the Solartron Varipak that came from Crowdhill. That was always likely to happen as I paid £10 primarily for its 20H 100mA choke (C-core) and associated mains transformer (also C-core). The Weston moving coil meter has been salvaged, as have a few other odds and ends, and BA faste...

As an insulator? Never tried, but it's probably quite good.

I've no experience at all of 1T resistors, but I'd imagine there are very respectable insulators with less resistance. I'd have thought producing meaningful results from them was a considerable exercise in advanced practical physics. Things you wouldn't normally consider, such handling them with yo...

1 teraohm is a large resistance, so leakage currents are a serious issue. Water condensing on clean glass wets it to form a leakage film. The earthed conductive paint band prevents leakage current end to end, diverting any leakage harmlessly to earth. Those connectors are MHV, which AI will tell you...

When people stop being suckered like that, industries stop selling products and force you to rent their products. Which is what is happening now with test equipment. Is a new 6 1/2 digit DMM better than one from the 1990s? Or 8 1/2? No. How about current probes? Are they cheaper than they were in t...

Zenith wrote: ↑Fri Oct 02, 2026 8:38 pm I have KEF C95s I've had for 35 years. They suit me.

If they suit you then don't scratch that tickle; it will only turn into an itch.

There was still a fair bit left after I'd filled the back of the car. With price of fuel it would not have been worth my driving there but I had to go within 10 miles for work for a couple of days so not so bad. Might have to go back to the work location next week. That's the main stack. There were...

Reminds me, I ought to flog my Rogers Studio 1. No use to me any more :cry: Are you sure? But if you are, sell them now because they are deteriorating all the time. @cubdriver: That's certainly a lot of cats. Not that I disapprove, but I once had four cats and that was tricky. Senior cat didn't app...

Not quite the same as gaining approval for range and depth* in test gear, but I think I have secured planning permission for new loudspeakers. On average, I make new loudspeakers every fifteen years. It takes me that long to forget how much effort and dust was involved. Naturally, each generation ha...

Thank you for that. I shall show SWMBO that things could be so much worse. But at least you have a cat in there, queen of all she surveys. Which is a lot. My bench has a shelf above it, stacked five high with DMMs, SMUs, etc, etc. An ex-colleague came round a week or two ago and was visibly taken ab...

No picture to be seen?

OK, so 4.5% error wasn't acceptable and I found I had some high value resistors. Sadly, I had to use two or three resistors in series to get the right value, so it's obvious someone has been in there. But the results are a lot better. As we used to say at the BBC, "Good enough for sport."

I've just calibrated the 610C against a Keithley 6221 current source, which is a much newer instrument and made to a rather higher specification. Measurement was by connecting an HPAK 34470A 7 1/2 digit DMM across the 610C's x1 output, removing moving coil meter linearity errors and making the measu...

I have just fitted a BNC on the back of the 610C in place of its strange original connector. This modification was a lot harder than the first as the hole (15.8mm) was far too large for any BNC. Also, it wasn't absolutely clear as to which wire was which, or whether one might float up to 120V under ...

I haven't needed to tweak the pots inside, but he's absolutely right about screening when measuring high value resistors. I have an earthed tin that plugs onto the front of a standard HPAK meter. With it, I can measure a 100M resistor that is impossible with ordinary leads. I haven't yet photographe...

Further investigation says that its input leakage current is of the order of 10fA, compared to the 3fA of a 6517B. That's almost certainly down to the construction/switching, not its MOSFETs. It zeroes happily in NORMAL mode (where it measures voltage drop across a shunt resistor), but a lot less ha...

This is going to be a rather short thread because the Keithley 610C that I bought for £10 five days ago works! The reason for the delay in testing was that I the 610C's input connector is a UHF socket and I didn't have a BNC to UHF adapter until half an hour ago. With the adapter, I was able to conn...

Yes, £10 was the right price. Of course, there's always the possibility the MOSFETs aren't blown up. Remote, but possible. I am awaiting UHF-BNC adapter to allow me to connect the 610C to current source and find out. Meanwhile, I have cleaned all the calibration stickers off. It's very nicely made i...

There used to be a bridge near Winchester known as the Spitfire bridge because local lore said a Spitfire was flown under it. Turns out it wasn't a Spitfire: https://www.sabre-roads.org.uk/wiki/Spitfire_Bridge RDH4 now turns up at radio rallies for about £30 (there was one at Rugby). I paid £70 for ...

Exactly my thought. I thought of you when I saw it, but (sadly)I didn't have room for books.

I had not thought about the effect of engine and elevators before, but I see what you mean.

I went on Concorde today. Not flying, sadly. Concorde 002, which was an engineering test bed, and now lives at Yeovilton. Fascinating. There were six seats at the back and the rest of the cabin was filled with 1960s data recorders. Probably FM tape-based. The cockpit was tiny and surprisingly simple...

Moving on swiftly, I've just bought another Weller TCP soldering station. I got an email from a friend to, "Come round ASAP, there's a spectrum analyser and oscilloscope you'll want." It was his next-door neighbour's who had died recently. The oscilloscope was a Gould and would probably fe...