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ignitron

>I just scrounged two massive ignitron tubes from a salvage yard.

>Manufacturer: Weltronic Ignitron 210-0147   NL-1052A   Size C
	Bet they are out of a scrapped out resitance welder, maybe.  They
	used to use em in cycloconverters.

>Anyone familiar with these things?
	Not THOSE.

>I tried digging thru my catalogs, Radio Amateur Handbook, etc., and I can't
>find  _anything_ on Ignitrons.
	Try looking under 'thyratrons'.  Differetn name for the same thing,
	as i recall.  Also try older books (used book stores) with names
	like 'industrial electronics'.  Older copies of 'electrical engineers
	handbooks'.

>I believe they're a rectifier/switch,
	Yup.  A controlled, mercury vapor switch.  (they CAN lose the vapor,
	in which case they are no good.)

>and they look like they have a control pin (grid, gate?)
	Yup.  they are a 'controlled diode'.  Need heater power like most
	other vaccuum tubes (as i recall).  Even with heater power and voltage
	across, they need a 'start' signal on the gate.  ONCE STARTED THEY STAY
	ON.  Turning the gate off (usually) does NOT turn them off.  (those
	familair with older solid state power devices will be saying:
		SCR.  SCR.

	Yep.  They act almost exactly like an SCR only MORE RUGGED.  In fact
	some folk call 'scrs' 'thyristors' from 'thratron'.)

	They can be used as synchronous rectifiers, phase control power
	controllers, etc.
	
	Hmmm.  I said they stayed on.  How Do They turn Off.  (like an SCR:
	current thru them drops to zero.  USUAL application, is on an AC line,
	two to do full wave, they get turned on, then turned off as the line
	goes thru zero, then turned on again.  by delaying the time int he cycle
	when turned on, one can control power, etc.  (phase control.)

	Inside, the gate controler makes (near?) contact with a pool of
	mercury (YES.  There is an UP side.  should be marked.).  The control
	electrode 'ignites' (not litteraly!!)  Pulls a small arc, the resultant
	plasma carries the power current, then goes out if the main current
	dies.)

	[I am doing this from fading neurons.  I THINK its accurate, but there
	are a couple of different, tho similar, mercury vapor styles of tube.
	They hadnle more power than a vacuum tube, since they use Hg plasma to
	carry the current.]

>They are water cooled.
	For low powers, could operate without water, for max rated power needs
	coolant.  Also not happy if over cooled.

>I'm sure I have a good find here, and I think they'd be good for exploding 
>wire/water stuff, and maybe as a good rectifier for building a d.c. Tesla 
>coil system, but I have no clue as to how to wire one.
	I would need to do lots book work & then YOU would need to do the same.
	IF they are functional (the Hg can leak out) they can be used.  If they
	ARE from welding gear (spot, or otherewise) they may have a low
	voltage rating.

	[coincidence is strange department:
	YEARS (DECADES) ago, my dad & i got my/our first coil (Model t Coil
	primary, etc...) running.  I began pestering about a 'big' coil, then
	(mid 50s) tube/candlestick coils were the rage.  (many hard workers
	have since proved otherwise...).  Well, turned out we had some
	'866 (?) anyway they were small mercury vapor tubes and some old
	transformers and we hacked away, based on the tube type plans.  And it
	would not work.  We pondered awhile & then figgered out about the
	"stays on" part of the mercury vapor spec.  At the time we dropped
	it.  Now, i could make it work,  (THOSE tubes were WAY smaller than
	what is discussed above.)]

	regards
	dwp