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Re: tubes
Anyone know of a good source of tubes in the UK. All you americans seem
to be surrounded in them.
Max Erhard
Tesla List wrote:
>
> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net>
>
> Hi Ed, all,
>
> > Original Poster: "Ed Phillips" <evp-at-pacbell-dot-net>
> snip
> > There were an almost infinite number of UV203A and VT4-C triodes
> > available surplus after WW2, and there are probably a lot still
> >kicking around somewhere. Nominal 50 watt dissipation, filament
> >3.25 amps at 10 volts. I suspect two or more in parallel would give
> >quite respectable performance.
>
> Uhm, I wouldn´t use a VT-4C or GL-211 (same tube, except that
> the VT-4C has military specs and is maybe more robust) for pure
> experimental work. The last time I saw one of these on the internet,
> they (a company) wanted $550 for one in original packing, mint
> condition and only 15 hours run time. I just happen to have one of
> these in the same condition with zero hours runtime. Hehehe ;o).
>
> However, if you can find them for cheap, they really should make
> a great toob TC. I got mine back in high school for just that purpose
> (for free). I had begun construction, but we moved over here around
> that time, so I had to discontinue work on it. Somehow, I lost one of
> the two VT-4C tubes I had ;,,,,,o( (sniff), so now I only have one
> left and that ONE is never going to be lit up. It is (among other tubes)
> just on display, next to my collection of old tube equipment. Now, I
> wish I had taken one of those gigantic rectifiers which my dad had
> used in his plasma lab (a picture of these tubes can be seen on my
> website). To give you an idea of the size of these monster mercury
> rectifier tubes: They are ~3.5 ft long and the lower glass tube is 10"
> in diameter. The globe (containing the plate) is roughly 20" in
> diameter. Did someone say huge tubes? I don´t remember the exact
> weight, but they were pretty heavy (as one can imagine, esp. since
> they were loaded with mercury). Would have been a cool addition to
> my small collection............
>
> More data on the VT-4C
> (original GE data sheet from 9-20-39 ;o)):
>
> Interplate capacitance (grid-plate): 14.5 µµF (µµF=pF)
>
> Jumbo 4 large pin base
>
> (all voltages are MAX values):
> --------------------------------------
> DC plate voltage: 1250V
> Grid voltage: -400V
> Plate current: 175 mA
> Grid current: 50 mA
> Plate dissipation: 100 Watts (Class C RF power amp)
> Peak RF grid input voltage: 375V
> Driving power: 7 Watts
>
> Under 15 Mhz the above values may be exceed by 5%.
> The resonance frequency of the grid-plate circuit is 100Mhz.
>
> The filament is of thoriated tungsten type, so it is best to
> use ac for heating, but it will need to be well watched, that
> the voltage stays within 5% of the nominal 10V
>
> BTW: If someone out there collects old German tube radios
> and needs a schematic, I might be able to help out as I have
> some 4000 pages of copied (puuh) schematics.
>
> Coiler greets from Germany,
> Reinhard