All which make repair extremely difficult! There are moves afoot in Europe, I believe, to introduce some sort of 'compulsory repairability' law, to enable freelance repairers to fix up stuff that's gone kaput. That would be an excellent idea, given the massive amount of electronics that goes into landfill. Our 'throw away culture' is not doing the environment any favours at all. This is what needs to be focused on, not some garbage about greenhouse gases.
He talked constantly about wine. That can kill your pancreas.
There are people who drink bottles per day.
The Bath Radio Club had a saying" "Amplifiers oscillate - oscillators don't".
My problem is that my oscillators oscillate too much.
Looks like it was designed in the late 60s! From the date code I believe mine is a 1982 model. It's still listed in the 1987 HP catalog for a list price of $1750. The 8013B is listed at $1650, maybe those prices are swapped. I wonder when they finally stopped selling it. It's quite a bit cheaper than the fully-programmable HP-IB equipped 8112A which listed for $4775.
It cost $1700 USD in the 1987 catalog, about $4500 equivalent today!
I heard that as "amplifiers will, oscillators won't"
:-) Gerhard
Our DDG is about $4K, addmittedly over the top for a home lab.
Am 02.04.24 um 17:09 schrieb John Larkin:
Wasn't that the scope that always switched off the beam current when things got interesting?
Gerhard
Yes, it shuts off the display often, to not wear out the microchannel plate.
One develops a sophisticated thumb-flic motion to hit the enable button in milliseconds. You can see a single-shot sweep at 1 ns/cm.
The 719 was a fast CRT scope too, but the screen was about the size of a postage stamp, and there was no vertical amplifier. I don't want one of those huge ugly beasts, but I do have a CRT. I dug it out of a 719 in a parking lot in Los Alamos, in the cold rain.
I bought a Siglent DDS SDG6022X for 1300USD, 200MHz thingie. I knew forehand that it could be hacked to 500MHz, so "saved" 3000 USD for 1 hours work :-)
Am 05.04.24 um 17:55 schrieb John Larkin:
Do you have slowish feedback into the source? From the FETs POV that makes it look like a capacitively loaded follower. It translates directly into a negative real part of the input impedance.
<It is the input impedance of 2*IF3602 and the negative real part can get REALLY large, out of bead-land. In the Smith diagram, S11 is decoded at the marker positions. Where the trajectory gets out of the circle through 0 and inf, there comes more energy back from the DUT than the VNA sends to it. Cannot happen with passive DUTs.
It is a really hard problem and even in AOE3 is a bad example.
I got an array of 16* CPH-3910 stable with feedback via a
3 GHz CFB amplifier. But CFB's 1/f noise easily dwarfed the noise of the 16 FETs even after 40 dB of gain.I tried driving the feedback with 2 * BFQ19S BJTs as a follower. It seems it kinda works in simulation. Generates a lot of heat. Not yet built.
<opinions or proposals?
Is it possible to get .ac and .noise analysis in LTspice in the same run without constantly editing the commands & the display???
Cheers, Gerhard
They've become reliable enough that there isn't enough business to support lots of shops, but even a smaller city like Boston still has a couple. There are Facebook groups dedicated to sharing tips for repairing them, too.
Not all TVs are "extremely cheap", some large displays cost several thousand dollars and since the most common faults are with the power supply, capacitors, LEDs etc. and often don't need a detail schematic to diagnose, they can definitely be economical to repair.
Video cards/GPUs are expensive enough nowadays that they're often economical to repair, too, they're a lot easier to ship than TVs so this one shop probably handles a significant fraction of the GPU repairs in the US:
The Infineon SiGe parts such as the BFP650 have AC Early voltages around
250V. (The DC curves in the datasheet are corrupted by thermal effect, and so exaggerate VAF, but it’s still very very good.).If you use one or more of those as cascodes, you can probably run a higher first-stage gain, which will help a lot.
Those BLF03VK and BLM15BA/BB beads are good for stabilizing them, but that gets harder at high collector current.
Cheers
Phil Hobbs
<snip>
The "garbage about greenhouse gases" that you want us to believe is spread by the fossil carbon extraction industry, who want to keep on digging up and selling huge amounts of fossil carbon to be burnt as fuel.
The mass of fossil carbon involved is orders of magnitude larger than the mass of material that being junked as consumer electronics, which is easy enough to recycle. Landfill is just land to be mined by the next generation.
Extra CO2 in the atmosphere is having nasty effects on the climate right now. Junked electronics in landfill doesn't do anything.
Do please grow up. Your petulant ignorance is irritating.
<snip>
Tomography isn't much good in cardiology. The heart moves around during a tomographic scan, and it doesn't do it predictably enough for a stroboscopic scan to work. Somebody tried when I was working at EMI Central Research in the late 1970s, and it didn't work well at all.
Superfast machines may do better but ultrasound is a lot cheaper.
It's also hard to see - the pancreas is a small organ - and it is impossible to do anything about it. One of our affiliated ultrasound clinicians when I was at at EMI, could find it quickly and cheaply with ultrasound, but early detection didn't save any lives.
But teetotallers still get it. In reality you have to smoke as well drink to increase your risk of pancreatic cancer. It can double the risk.
Excuse me for being a bit slow on the uptake here, but it seems to me that there are a *lot* of products which are fundamentally all manufactured to the same spec - but then deliberately crippled unless you pay some sort of ransom to have them 'unlocked' as it were. Would that be correct or am I being too cynical?
Oh yes, he loved his wine alright. As I recall, you sent him several cases of the stuff over the years. But no amount of peace offerings could placate Jim if he felt you'd disrespected him. Anyway, all credit to you for at least trying to heal the rift, even if it came to naught.
No, but is differentiating products on softwar supplies any different from differentiating them on hardware? Cheap ones simply wouldn't be available to hobbyists if they had to sell them all as top of the range, where they make the money for the effort to make a high bandwidth scope. There is also the advantage that they can perhaps be hacked by well-informed hobbyists, but most commercial buyers wouldn't be happy doing that for one or another reason.
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