John Larkin
Cool, great, yes those are not really RF blocks...
You should in, a free moment, read one of those old RSGB handbooks. All about construction of RF circuits up to some GHz. I sure learned a lot from that, as a kid.
No longer have the old RSGB handbook, mine from the tube era, but still can visualize pages from it...
Spice, there was no spice, you measure things.. if you can...
PS, those terminal blocks are not really that good, I get bad contact at DC with those too, finally soldered the wires:
Maybe one should not use tinned wire, but I do have high resistance effect. So it needs not be a RF problem, could just be resistive heating. Use the good old amphenol PL259 connectors for high power RF:-)
Jasen Betts wrote in news:pq183r$40d$ snipped-for-privacy@gonzo.alcatraz:
Fail? No. But folks like you get impatient and start pointing fingers.
So, POTS didn't do it... an impatient blametard did.
wrote in news:pq1h3u$1133$ snipped-for-privacy@gioia.aioe.org:
Those are ideally meant for a solid wire. Their original design debut was. For stranded, one needs to crimp on a pin to the wire end or fudge that by tinning a segment of it, but then one must read up on the possibilities of a fail mode due to "solder creep". Generally not for small signall, but for power, solder creep can be an issue.
Also high strand counf SPC wire instead of that cheap, low strand cound, bad copper, pvc coated crap wire there, you would get better results as well. SPC teflon sheathed wire spools are pretty cheap.
cable/dp/
The Phoenix ones are fine. Some cheap ones are, well, cheap. Thermoplastics will flow and loosen up, which can be thermal runaway.
My customer's gadget uses stranded wire. Those little Phoenix blocks have a very well machined (and hard to remove!) clamp mechanism that works well on stranded wire.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I may have discovered a weird thermal runaway mechanism. Possibly as temperature increases, more current shifts from the schottky junction into the guard ring, reverse recovery dissipation increases, and boom.
I might try some silicon carbide. More Vf but no guard ring.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Wouldn't be surprised. Schottkys don't have the same tempco as PN diodes.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Recovery tempco is brutal. It's always a runaway (bistable) system. It's only a matter of having enough cooling / little enough dissipation that it doesn't quite get there.
Guard ring is still there, they just don't always show it. Infineon datasheets I think usually go there, you see a step change around 4-6V forward drop, depending on temp. No good for surge (they're probably not made with big enough dies / heavy enough metallization to handle useful surge in the first place), but you have all that clean, juicy SiC performance at currents below there.
I'm sad no one makes an 0.5A rated diode in SMA package.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
I'll be pushing maybe 10 to 15 amps in a short pulse, and I'll be back-biasing the diode fast at the end. I will be expecting numbers like 1.5 volts forward, which sounds safe based on your 4-6 volts for the guard ring.
Most of the SiC parts are high voltage, 600 to 1200 roughly, and 2 to
20 amps or so.This is cute, but the price is insane.
There are some 1 amp parts in SMB. Maybe some melfs?
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
To get there, you'll need pretty much a 4-8A diode. You'll have to check if it's worth the extra capacitance, or if you need to eat the losses with a bigger heatsink.
There's always your old GaN friend, a few EPCxxx stacked would do almost as well, with a tiny fraction of the capacitance. And you already have some familiarity with mounting and sinking them.
There are bigger, hotter (~600V) GaNs on the market now, which may be a better fit (less Vf than a stack).
^ ^ ^
Yeah, like I said, they don't exist. :^)
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
I dropped a Cree C3D03065 into my Spice model, and it worked fine, about 2.5 volts peak forward drop, 1.9 watts dissipation.
But the silicon schottkies Spiced fine, too. Nobody includes guard rings in their models.
I was thinking about fuel dragsters and tractor pulls. About two seconds into every third race, the entire engine explodes and flames and hunks of metal fly out. So back to the shop for a total rebuild. I'm starting to know how they feel.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
This part's data sheet seems to show a PIN diode in parallel with the SiC schottky.
The PDF tells me to copy the model and put it into Spice, but it's secured so Foxit doesn't allow me to copy it!
grrrrr.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
I load it in OpenOffice V3.2.0. You can copy sections to the clipboard or print the entire thing to a PDF. This removes the secured block. The new PDF may be larger than the original, but you can at least get your data.
Evince allows me to copy it, all the tabs are line breaks in the copy. here it is reformeatted
* MODEL OF GeneSiC Semiconductor Inc. * * $Revision: 1.0 $ * $Date: 09-SEP-2013 $ * * GeneSiC Semiconductor Inc. * 43670 Trade Center Place Ste. 155 * Dulles, VA 20166 * * COPYRIGHT (C) 2013 GeneSiC Semiconductor Inc. * ALL RIGHTS RESERVED *-- Notsodium is mined on the banks of denial.
The spice file is at
It is not secured.
Well, you could take a screenshot, make it into a PDF, and then OCR it at .
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Great, thanks.
This is a nice looking part, the only SMB SiC diode I have seen, fairly low capacitance, but it may not be available. I've pinged the local rep.
Their web site is terrible.
genesicsemi.com
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Steve got it for me, but I can't get it to run.
I suppose I'll buy something else.
Someone, epc I think, actually supplies instantly-working LT Spice models and runnable .asc circuits.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
This is barbaric. But it does in theory let me separately snoop the schottky and PIN (guard ring?) currents.
I wonder if it models reverse recovery right. Next thing to test.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Selects fine in Chrome PDF viewer...
WTF, there's no equals signs in the models? Does LTspice actually stoop that low?
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
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