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## Re: [Amps] Design VS parasitic

 To: amps@contesting.com Re: [Amps] Design VS parasitic Alek Petkovic Tue, 25 Aug 2009 07:08:31 +0800 mailto:amps@contesting.com>
 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. 73, Alek VK6APK 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 wrote: > > > ORIGINAL MESSAGE: > > > > On Mon, 24 Aug 2009 12:44:13 -0400, "Carl" 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 > > _______________________________________________ > > Amps mailing list > > Amps@contesting.com > > http://lists.contesting.com/mailman/listinfo/amps > > >_______________________________________________ >Amps mailing list >Amps@contesting.com >http://lists.contesting.com/mailman/listinfo/amps http://www.qrz.com/vk6apk http://www.qrz.com/vk6py _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps