** I adjust the grid potential so that there is no grid current under max drive. There can be grid current only if a more powerful driver is used. ** Which is why I adjust the grid potential for zer
not is amen, Gary _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
** Which why it's better to tune up a SSB amplifier with a string of pulses instead of AØ / NØN ** It seems to me that a sag in bias potential would simply increase ZSAC slightly -- wh
** The grid does not and can not draw current when a competent operator sets the grid potential just above the level where it can draw grid-current with the max PEP drive that's available. This is t
** amen. Sophisticated electronic regulation in high RF fields is definitely not a piece of cake. ** The circuit at: http://www.somis.org/D.a.04.GIF can easily handle 10mA of grid current, it switch
** Yes. The easiest way to control power is with the microphone gain control. When the microphone gain is reduced to the point that the amplifier's anode current is constant during modulation, the a
** Good point, Gary. _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
** So you are essentially saying that if the grid terminating resistor is blown away by the exciter, the grid driving potential could rise to a higher level and grid-current could flow? Although thi
** Not quite. I do not use a regulated bias supply because the tube manufacturers specify a maximum bias supply impedance for AB1. Typically, the max Z spec is 100k-ohms. The bias supplies I use hav
** All transceivers overshoot. A competent operator knows to Not tune up a Class AB1 amplifier for SSB use with AØ/NØN/"hammer-down" because the peak output V will not be developed fro
** This situation is virtually guaranteed to happen if an AB1 amplifier's G1 DC bias is adjusted using AØ-mode. However, if the DC grid bias is set so that no grid current flows on the first
... ** A 4cx1500A and larger, similar tetrodes can be rebuilt >20-times by recarburizing the thoriated-tungsten filament/cathode. Each rebuild is good for c. 20k hours of useful emission. ___________
** WHAT WAS WRONG WITH THE 3, ORIGINAL TUBES? _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
** Do you mean a grid-filament short? Do you see springs floating around in the bottom of the glass envelope? _______________________________________________ Amps mailing list Amps@contesting.com htt
** A grid-terminator R either soaks up the power or it don't. If it doesn't soak, it's croaked. - If the grid-terminator is present and intact it presents the design impedance at the grid over the f
** Eimac's data sheet for the 4cx3000A/8169, page 4: "The circuit resistance of the grid circuit should not exceed 100,000-ohms". ** RE: Svetlana data sheets for the 4cx800A, "Control Grid Operation
** Good one, Craig. One problem is trying to convince the ignorant that mo' ALC is not mo' betta. Another problem is manufacturer's owners' manuals which recommend using a certain level of ALC. - suc
** The advantage of the ...J over the standard ...D is that the ...J's filament/cathode has c. 7A more peak emission -- if it is ever needed. The result is flatter constant-current curves, especiall
** I see c. 20% overshoot on my TS-440S on the first syllable. Running almost no ALC helps. ** Without some form of ALC, excess IMD is a virtual guarantee -- unless the operator religiously rides he