Someone did send me a couple of the tiny tubes that were used in WWII proximity fuzes, shot out of guns at 20,000 Gs. They helped enourmously late in the war, against the kamakazie in the Pacific and against German aircraft over England.
and I have a krytron!
These were used to fire the many detonators on the first few generations of implosion-type plutonium bombs.
Not to worry. Vacuum tubes might be making a comeback in the form of vacuum channel transistors: The main benefit is low noise: (All I know about these is what I've read in various articles).
Drivel: I still have a tube caddy somewhere.
Back to lying and cheating on my taxes...
People have been trying to make heater-less tubes for decades now. They have tried carbon nanotubes, microtips, and vacuum diodes as the emitter, but so far all such cathodes destroy themselves quickly.
A sharp metal tip can have a high enough local field strength (like,
10^8 v/cm) to fling electrons off into space, but then tends to fling atoms off the tip, too.** The name "Kamikaze" was given to Japanese suicide attacks on US navy vessels by manned aircraft late in WW2 while the only German aircraft subjected to proximity fused shells over the UK were unmanned V1 cruise missiles.
Proximity fused shells were also used in the "Battle of the Bulge" against German ground troops - having the shells explode while still in the air increased their lethal range greatly.
.... Phil
Such a shame leaving them float around though -- should do something with them, some rainy day maybe. (Hey, you've got enough of those down in the 'Bay area, right?..)
The G-ratings on those are pretty impressive (somewhere around smacking a concrete floor, or... being shot out of a cannon, oddly enough), though I doubt they were rated for much lifetime. Probably, they'd still run just fine as, like.. a cute superregen receiver, at reduced emissions to keep enough life as a display curiosity.
Mine* do a pretty fair job in the shortwave band:
Does it glow if you put a few mA into it (at enough voltage to do something)?
Would make an interesting product, if you one day find a customer that needs a 10kV+, nanosecond pulse, without the bulk of a saturating magnetic compressor. Probably not reliable enough for test equipment though... let alone the availability. ;-)
Speaking of hot pulses, I wonder what those handheld XRF guns have inside 'em. That's something I'd *love* to see Mike get his hands on -- assuming the thing is worth more as a teardown curiosity than on the market, whole.
Tim
Yup.
As I recall, they were deployed in the Pacific on priority, but they were considered such a valuable secret that they didn't want to use them over open land, until late in the war. Evidently the Germans had indeed begun to piece them together once they were introduced there -- but by then it was too late.
Also, for whatever reason, they gave them the technical term "fuze".
Tim
I can't wait until something like a heaterless 300B is available in a TO-247 package. You know, just to piss off those damn audiophools. ;-)
But, I suspect we'll be waiting quite a long time for such products.
Tim
Nice. Prox fused shells were also very lethal antipersonnel weapons late in the war, especially in the Battle of the Bulge. Having the shell burst 10 feet in the air versus ten feet underground makes a big difference.
It looks like krytrons are off the U.S. Munitions List, but they're still classified as dual-use, so you have to worry about the Commerce Department regulations, if you were ever tempted to take your collection on vacation with you. ;)
I always take a scrubbed laptop when I go out of the country, for the same sort of reason.
Cheers
Phil Hobbs
'Fuze' is the usual name in ordnance circles, I think. Removing a fuze is quite different from removing a fuse!
Cheers
Phil Hobbs
The vacuum channel xsistor uses helium to reduce the probability of an electron hitting a gas molecule. Using low voltages allegedly reduces cathode errosion. There's a section on the topic in: "If the impact knocks a bound electron from the gas molecule, it will become a positively charged ion, which means that the electric field will send it flying toward the cathode. Under the bombardment of all those positive ions, cathodes degrade. So you really want to avoid this as much as possible. Fortunately, if you keep the voltage low, the electrons will never acquire enough energy to ionize helium."
Unfortunately, the devices will probably be too small for my tube caddy.
Not really. If either is removed, the widget is inert.
After it's done, sure. But the fuze-removal process can be a bit ticklish if the ordnance is armed already, no?
Cheers
Phil Hobbs
-LAsse
Amazingly self serving piece of soviet bashing in the introduction. For those not in the know, the MIG 25 foxbat was designed to intercept nuclear bombers during a full exchange of weapons. Originally it was intended as a counter to the XB-70 Valkyrie (a stunning and magnificent aircraft) which was canceled, but a Mach 3 aircraft is good for intercepting a lot of things and for photo reconnaissance.
When considered in its intended role, EVERY one of the early criticisms of the MIG 25 turns out to be false, misleading or irrelevant.
The MIG 25 is made of steel not titanium. Steel provides much greater protection from EMP effects of nuclear detonations which were expected to be both close and frequent.
The MIG 25 uses valves not transistors for the same reason. It is not crude, but rather it is the best, and possibly the only workable solution to the problem.
MIG 25 missile fire control is bizarre and locks out firing another volley of missiles for (originally IIRC) about 30 seconds - again this relates to an environment full of EMP's - it stops misfires due to EMP.
The foxbat's engines have extremely short lives at MACH 3 power levels and a lifetime of a single mission at MACH 3.2, but then in a full scale nuclear exchange that is irrelevant.
When war comes to Ukraine or Latvia or Lithuania or wherever Putin next desires (Putin is a pig who can't rein in his own desires - he will send the world to war just because of his ego), the US will have a few nasty shocks. For example in Vietnam the US started using SHRIKE to destroy missile air defenses, and it was effective until the operators figured out how to decoy it. So the US developed HARM which was the same thing but faster. In Yugoslavia one SAM site survived being targeted by over 200 (!!!) HARM missiles - by using the same tactics as the North Vietnamese. And HARM is still (!!) the first line air defense suppression weapon - talk about slow learners.
rant done. i'll pass on battle field air support and mobile air defenses for now.
Men's cologne and cow poop--there's a combination for the ages. ;0
Cheers
Phil Hobbs
Yea; one could use some transfer curves, like Vce(sat) and Ic ...
not only cologne, but cologne branded by celebrities
it's got to take some very special persons to defuse a 500kg bombs by trial-and-error knowing that error result in, as he put it, "pink mist"
-Lasse
Hmm, I'm thinking that is pretty common with the dairy farmers in my parts, out for a date on Saturday night. :^)
George h.
We should drop barrel bombs on those ISIL creeps, full of cheap perfume.
Bacon grease.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required