Fwd: Re: MHz - VTTC

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>


>Date: Tue, 20 Apr 2004 17:05:33 -0600
>To: robynsaddiction-at-aol-dot-com
>From: "Wim Bosma" <wbosma-at-stud.tue.nl> (by way of Terry Fritz 
><teslalist-at-twfpowerelectronics-dot-com>)
>Subject: Re: MHz - VTTC
>
>The 4-125A tetrode has an effciency of up to 75% in class C at anode voltage
>3000 V, grid2 voltage 350 V,  grid1 voltage -150 V. Anode current 167 mA,
>grid2 current 30 mA, grid1 current 6.5 mA. Output power 375 W. Anode
>dissipation 125 W: anode redhot (+850 C). Driving power is 2-3 W. Most
>values differ with other anode voltages. Rule of thumb for tank circuits:
>use a loaded tank Q of about 10 for ease of coupling and efficiency. A
>higher Q results in higher tank current with increased losses. A much lower
>tank Q results in less efficient operation of the tube and stronger
>generation of harmonics. The tank capacitance depends on the ratio: plate
>volts/ plate current and on the frequency. Doubling the C (and thus halving
>the L) will double the loaded Q. For a class C tube: Rload = plate volts/ (2
>x plate current). For a class B tube: Rload = plate volts/ (1.57 x plate
>current). In the above case of the 4-125A at 1 MHz, I guess the tank C would
>be about 200-400 pF, but I leave it to you or betters to find the correct
>values.
>Regards, Willem Bosma, PA0TW
>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Tuesday, April 20, 2004 3:45 PM
>Subject: MHz - VTTC
>
>
> > Original poster: herwig.roscher-at-gmx.de
> >
> > VTTC coilers,
> >
> > Did somebody manage to operate a VT e.g. 4-125A in the lower MHz
> > range? I am interested in the optimal values or the L/C relationship
> > of the tank circuit.
> >
> > Cheers,
> >
> > Herwig