[R-390] Casual Ballast Fillament Draping Specifications

[Michael Murphy]

I beleive that technique developed at Draper labs.

Mike WB2UID


----- Original Message -----
From: "Barry Hauser" <barry at hausernet.com>
To: "Bob Camp" <ham at cq.nu>; "Bruce MacLellan" <brumac at juno.com>
Cc: <R-390 at mailman.qth.net>
Sent: Monday, July 05, 2004 9:43 PM
Subject: Re: [R-390] Fw: Re: Lutefisk and The Ballast Tube Thread - on
topic-Haa! - Take that


> > I'm not real sure we know what the process was that they used to
> > manufacture the ballast tubes.
>
> Probably not too many possibilities.
>
> > It's pretty obvious that precision wire placement and careful insulator
> > assembly were not part of the process.
>
> Yea But Dept:  There might be some plan to the apparent casual drape to
the
> filament.  Maybe some "knack" is involved.
>
> We obviously have the skills to
> > figure out the wire length, wire gauge, and wire composition they used.
>
> Supposed to be drawn iron.  The trick is to get all those little
curli-ques
> into it.  Heck, keeps breaking when I just do one turn.  I suspect a
diamond
> edge potato peeler affair -- like a wood plane where the shavings come off
> curled.
>
> > No way are you going to convince me that anything closer than a 10%
> > accuracy is needed in ether wire length or diameter.
>
> I won't try ...
>
> >
> > If we send out a tube or two for a residual gas analysis we'll know
> > what the gas mix they used was. The only other variable would be
> > pressure.
>
> Supposed to be either hydrogen or helium -- one way to find out:  Throw a
> bad tube on the barbeque and see if it goes pop-flash, as opposed to just
> pop .. uh nuthin.
>
> >
> > My guess is that they did a very normal bake out with a vacuum pump on
> > the tubulation. Once the thing is clean on the vac ion gauge you fire
> > up the wire with a constant current source. Then you back fill the tube
> > to the point that the voltage on it drops to a specified value. More or
> > less it's a thermistor vacuum gauge in reverse.
>
> Sounds complicated.  Since these were filled with gas, was it necessary to
> apply vacuum first.  Blast the gas through which would displace the air.
> Question of whether it's cheaper to waste some gas.  Might be
problematical
> with hydrogen.  Probably assembled in a vacuum cage, then H or He sucked
> into it.
>
> >
> > Once it's stable with a given gas level you can sweep it to check it's
> > regulation. If it passes you seal it off.
>
> Maybe on the prototype, but production runs?  Just assemble pins/rods,
slip
> on the micas, drape the required length of iron wire (with curlycues),
weld
> the ends to #2 and #7 pin, et.
>
> >
> > If the process is really that simple - why the high cost for these darn
> > things? They never have been cheap. The process can't have been as
> > extensive as a normal vacuum tube. If we have the skills to figure out
> > the details then anybody in the tube business could have.  Again - why
> > should these cost so darn much ....
>
> Two reasons -- Virtual monopoly & the highly influential Ballast Tube
Lobby.
> (Sen. Joe McCarthy was merely a diversion.  "Y'mean you're gonna charge
the
> govament $50 bucks for a bulb that hardly lights up!"  " Shuddup and go
> chase some comminists!"  "What if they aren't there?"  "Chase 'em anyway
> udderwise someday when you go to start your car, there might be a
trunkload
> of free samples, with one wired to the starter switch!)
>
> Hey, look - it could have happened that way.  Just keep watching the
History
> Channel for when it gets declassified.
>
> Barry
>
>
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