On the contrary Jack. The wire is comparable in diameter to 20 Amp
fuse wire so I don't believe 1A plate current will present any problems.
At 04:23 AM 25/08/2009, Jack Shirley wrote:
>The nichrome wire supplied seems somewhat small in diameter for
>a 1 A plate current.
>73 N8DX Jack
>On Mon, Aug 24, 2009 at 1:28 PM, Bill, W6WRT <email@example.com> wrote:
> > ORIGINAL MESSAGE:
> > On Mon, 24 Aug 2009 12:44:13 -0400, "Carl" <firstname.lastname@example.org> wrote:
> > >And also please explain why the natural parasitic frequency of a tube as
> > >determined by math and in a test jig doesnt change, except minimally if at
> > >all, when in an amplifier circuit.
> > REPLY:
> > I had never heard of "the natural parasitic frequency" of a tube until you
> > mentioned it in a previous post. I am assuming you mean the combination of
> > anode-to-grounded-element capacitance together with the internal lead
> > inductance?
> > Of course that characteristic of a tube is a SERIES resonant circuit and
> > will
> > not sustain oscillation by itself. You must connect the tube to the
> > operating
> > tank circuit and by doing so, you inadvertently create a PARALLEL resonant
> > circuit which is the actual source of the high VHF impedance necessary to
> > sustain VHF oscillation.
> > The length of those connecting leads is highly important in establishing
> > the VHF
> > parasitic frequency and shorter is always better. Shorter leads moves the
> > VHF
> > resonance higher where tube gain is less and parasitic suppression can be
> > done
> > with a smaller inductance, which reduces the tendency to smoke the
> > suppressor
> > resistors when operating in the high HF region.
> > This should not be confused with the natural self-neutralized frequency of
> > a
> > tube. That frequency applies to the actual operating frequency, the
> > frequency
> > being amplified, which is entirely different from the VHF parasitic
> > frequency.
> > 73, Bill W6WRT
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