Fw: Re: deForest did it, so can we.

[riese-k3djc at juno.com]

I dont think this is an Urban legion but I recall that in the 50s ? there
was a ham that built his own high powered triodes and used them in an
amplifier. I think this was written up in QST. The ham may have been from
Gettysburg

Bob K3DJC





On Mon, 19 Jun 2006 22:45:17 -0400 "Bob Bruhns" <bbruhns at erols.com>
writes:
> Wow, that's a cool looking tube.
> 
>   Bob, WA3WDR
> 
> ----- Original Message ----- 
> From: "hal" <hfeinstein at cox.net>
> To: <tacos at amrad.org>
> Sent: Monday, June 19, 2006 10:31 PM
> Subject: Re: deForest did it, so can we.
> 
> 
> > This URL is a picture of a home made audion. Its made from a bell 
> jar. 
> > An ashtray is used
> > for the base. Rob, where do you order tantalum wire from? And is 
> the stuff
> > dangerous to heat up and work with?
> > 
> > 
> http://www.sas.org/tcs/weeklyIssues/2004-05-28/review/art/triode2b.jpg
> > 
> > 
> > 
> > 
> > Robert E.Seastrom wrote:
> > > hal <hfeinstein at cox.net> writes:
> > >
> > >   
> > >> (2) Next skill, what do you
> > >> make the filament out of?  I think you can buy thoriated
> > >> tungsten, yes, but  I wonder what old DeForest used for
> > >> his filaments?  Nickel wire? 
> > >>     
> > >
> > > wikipedia article:  http://en.wikipedia.org/wiki/Audion_tube
> > > has a link to the patents.  841,386 says in part:
> > >
> > >    While various means may be employed for heating said gaseous 
> medium I
> > >    find it convenient to employ electrical means and, therefore, 
> I prefer
> > >    to employ as the electrode F a filament of carbon or metal 
> and to
> > >    connect the same in series with a battery B' and a rheostat 
> R'.  I
> > >    have ascertained that a filament of metal, especially one of 
> tantalum,
> > >    renders the oscillation-detector much more sensitive than one 
> of
> > >    carbon.
> > >
> > > it is not surprising that deforest would try tantalum as it was 
> an
> > > interim filament material in light bulbs after carbon lost 
> popularity
> > > and before tungsten was adopted (tantalum is pretty friendly to 
> work
> > > with whereas tungsten is not very ductile - not sure what was 
> done to
> > > be able to work it into light bulb filaments, but i suspect that 
> it
> > > probably involved super high purity and very carefully 
> controlled
> > > alloying).  according to sylvania's web site, the thoriated 
> tungsten
> > > wire is preferred for arc lamps and power tubes.
> > > 
>
http://www.sylvania.com/BusinessProducts/MaterialsandComponents/Electroni
csDisplayProducts/TungstenWire/
> > >
> > > but i digress.  tantalum wire is not particularly expensive 
> stuff,
> > > considering the quantities of it we're anticipating using.:
> > >
> > > http://www.sisweb.com/ms/sis/wire4.htm
> > >
> > >                                         ---rob
> > >
> > >
> > >   
> > 
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> > 
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