Author Topic: Dynode  (Read 6391 times)

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Re: Dynode
« Reply #16 on: December 20, 2017, 03:13:27 am »
I was recently given an old Dynatron oscillator box which uses Farnsworth's 1012 A vacuum tube.  This is a hv pentode having three grids, two of which are coated for secondary electron emission.  So this dynode operates in the negative resistance region.  The tube is spected to operate at up to 330 Mega Hertz, but the circuit in mine outputs 28 MHz.

This unit was a donation, so I'll pass it on by posting some pictures of what's inside.

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Re: Dynode
« Reply #17 on: December 24, 2017, 02:38:33 am »
thatd be nice....I have a box of tubes id like to understand how to use them as well :)

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Re: Dynode
« Reply #18 on: December 25, 2017, 08:19:59 am »
thatd be nice....I have a box of tubes id like to understand how to use them as well :)

Vacuum tubes are versatile.  Some of them have applications which can't be filled with solid state - for instance, the Farnsworth like 1Q3, the "split the positive" 6146A, and now this six and a half inch top hat 1012.  I've been working on getting some pictures uploaded.  A couple of hours today got a few images sized and formatted, but nothing hosted yet.  Tomorrow I'll be busy talking to the Sheriff about the latest prowler incident (about an hour ago), but I'll see if I can find some time to post something.  Finding information about the Dynatron was difficult and time consuming, and that search will have to be repeated for me to post those links which couldn't be saved at the time.  And it's fire wood season, which limits my time for productivity.

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Re: Dynode
« Reply #19 on: December 28, 2017, 00:40:47 am »
Here's some pictures.  I'll post some discussion when I have some battery time on my computer.












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Re: Dynode
« Reply #20 on: December 30, 2017, 02:30:39 am »
There's a lot of stuff to look at inside this cabinet.  A label on the red tube which contains the tuning crystal says that all of the caps are .02 mfd, and are rated for 10 kV.  So the transformer must put out around 5 kV.  It's comparable to a large MOT, so it's at least a kW.  The meter on the front goes to 1,000, but the maximum fuse size is 6 A, so the unit's power output must be between five hundred and seven hundred W, rf.  And it's pretty tricky how the angle of the internal coil in the center tapped tuning inductor varies the inductance of that coil's lower half.  The rotatable coil capacitively couples a third coil around the very bottom of the coil form into the circuit.

The vacuum tube itself deserves its own post.

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Re: Dynode
« Reply #21 on: December 31, 2017, 03:22:33 am »
Thats extremely interesting !!! The tubes I have came from an oscilloscope ....nothing like the unit you have there.I hope you find it useful !!!

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Re: Dynode
« Reply #22 on: January 13, 2018, 00:12:38 am »
off topic:

I'm correcting my usage of "aluminum"..  In fact, I've always prefered the correct spelling, since that's the way it used to be.  (I have at least two patents on my hard drive - from the 1930's -  which include the word aluminium.  (a-lu-min-ium or a-lu-mi-nium)  I always figured the word being truncated was part of the 'duming down' characterised by changing the term hominid sapiens to homo sapien.  (One of my teachers back in high school said the latter term was changed because we were "too stupid to be able to say it correctly".)

Speaking of Stupidity, I've finally determined, with certainty, who has been systematically vandalizing my property and vehicles for the past six years.  We just had a couple of days of rain, and him and his 'rifle man' accomplice showed up the next night, right after the rain.  The next morning, both sets of tracks were well defined in the wet sand of the 21st street wash the neighbor uses to get out here to his storage property (or drug processing facility), tracks from both his pickup coming to the point where he turned around at the corner of my property, and the atv which went up to the top of the hill by my fence on the south.  This guy recently made contact with me, on a friendly basis, but turned out to be an aggressive homosexual.  He physically attacked me a number of times (I'm an Untouchable), then came over one day and fired off a full clip from his 9mm right in my driveway, without my knowledge or consent.  After I forcefully chewed him out and told him to stay away, he appears to have revealed a homicidal side of his psychopathy.  He previously shot holes in every vacant house out here AND all of the junk cars on my property.

Time to charge weapon systems.  I still have a good supply of Mercury on hand, but I'm having a hard time finding a quick source of Iodine crystals for my 'spy glass', to focus the laser pointer and/or flashlight through the wall so I can see him without even opening a curtain.  But a deputy has told me I have the right to do "whatever it takes" to protect myself and my property.

"Under Natural Law, Stupidity is a capital offence; in the world of Nature, the penalty is swift and certain" - Robert Heinlein.  I previously told this guy that I'm out here on the edge of civilization, trying to minimize contact with the neighbors.  Then he actually INCREASED his physical aggression.

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Re: Dynode
« Reply #23 on: January 13, 2018, 18:46:23 pm »
off topic:

Someone hacked my phone and disabled the URL function.  I guess they didn't want me to say anything about the way smoke from the fuming Iodine condenses on the surface of the Mercury, forming a fractal pattern with holes which are so tiny the reflected beams of light are so narrow they pass between the molecules of the wall.