Re: Tube Data
I'm not talking about the parallel LC circuit, I'm talking
about the tube driver. If you use a tuned tank with a tube this introduces
a whole new bunch of problems, as the tube tank circuit, not having all the
series R of the spark gap to limit the Q will exhibit a fairly large voltage
rise which can damage the tubes...... all a bit more than I like to worry
> Original Poster: "Simon Winder" <swinder-at-microsoft-dot-com>
> Are you sure?
> At resonance the impedance of a parallel LC is infinite.
> Surely the tube sees the corona load impedance transformed into the
> -----Original Message-----
> From: Tesla List [mailto:tesla-at-pupman-dot-com]
> Sent: Thursday, February 24, 2000 8:25 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: Tube Data
> Original Poster: "Megavolt Nick" <tesla-at-fieldfamily.prontoserve.co.uk>
> Hi All,
> One of the main characteristics of an electron emission device
> like a vacuum tube is that it will have a comparatively high output
> impedance. The tube I mention below can supply 400ma at 5kV -
> Z = V/I
> Z = 5000/0.4
> Z = 12500
> This means that to avoid damaging the tube the load connected to it must
> have an impeadance of at least 12.5 kiloOhms. Therefore it must use a
> primary coil with a large inductance to provide this impedance.
> For a typical disruptive TC operating at 300kHz with a 0.1µF primary
> capacitor you would need about 28µH of primary inductance to tune, which
> an impedance of only 5 Ohms; whereas a vacuum tube design would use a much
> larger primary to provide the large impedance, about 6.6mH would be
> This arrangement would suit a magnifier system as the large primary needed
> could be wound co-axially with the secondary for most of its length giving
> the very high K factor a magnifier needs.
> Nick Field
> > Original Poster: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz>
> > Hi Nick (and others who have said such things in the past):
> > > Original Poster: "Megavolt Nick" <tesla-at-fieldfamily.prontoserve.co.uk>
> > >
> > > Hi Guys,
> > > thanks for all your help. I've eventually managed to get
> > > data from an online database. Its a 2250W transmitter tube. The
> > > dissipation is 500W, plate voltage 5kV, anode current 400mA.
> > > I wonder if anyone has ever tried a tube driven magnifier?
> > > To get the impeadance match right you'd need a large primary which
> > > suit the tight coupling of a magnifier driver.
> > Could you expand on that last statement and perhaps throw some
> > meaningful figures in for us to see please?
> > Regards,
> > Malcolm