For linear purposes, 813's work in grounded grid with the screen tied to the control grid and grounded. You can also make a class AB1 amplifier with a 'grid circuit' consisting of a big 50-ohm dummy load. And then there is the G2DAF circuit, in which the screen voltage is derived fom the drive -- but I only recommend this one for SSB if you have a means for checking IMD; it may require some careful adjustment.
I'll put up the report on my amp soon. I need to redraw the schematics which are a horrible mess at present. On 12/22/2010 8:30 AM, Dale Parfitt wrote: > Hi Vic, > Dave Ishmael has a single 813 amplifeir in this month's Electric Radio. > Please do publish > your amp for all of us to look at. I still have an 813 and socket I have had > since I was a > kid- maybe it's time to build an amp for my Atlas 350XL. > > Dale W4OP > ----- Original Message ----- From: "Vic K2VCO" <[email protected]> > To: <[email protected]> > Sent: Wednesday, December 22, 2010 11:14 AM > Subject: Re: [Elecraft] 100 Watts or 500 Watts > > >> I just finished building a grid-driven amplifier using two 813 tubes. With a >> 3 db >> attenuator at the input, it requires between 16 and 40 watts of drive on 160 >> through 10 >> meters respectively, for 800 watts output (only 700 on 10). Without the >> attenuator, it >> would need 8 - 20 watts drive. >> >> And this is a class-C amplifier designed for CW only! If it were a class B >> or AB linear, >> the drive requirement would be even lower. >> >> Grounded-grid is not the only way to design a tube amplifier. Although a >> traditional >> grid-driven circuit is a little more complicated, it's one way to get more >> gain. >> >> I am going to put some pictures and schematics on my web site soon, not that >> I think >> anyone will want to duplicate it! >> >> On 12/22/2010 7:50 AM, Ron D'Eau Claire wrote: >>> Even the Elecraft 100 watt amps are integrated with either the K2 or K3 >>> control logic so they cannot be used as a stand-alone amplifier with other >>> transmitters. >>> >>> The only reason I have ever seen from the FCC for the amplifier >>> certification and 15 dB gain limitation is to discourage the CB >>> 'bootleggers'. Certainly building a stable, clean amplifier that would take >>> even a few milliwatts to 1000+ watts is a straightforward design exercise. >>> There's no real problem with using more than one stage of gain if there was >>> no 15 dB limit on the system gain. >>> >>> Ron AC7AC >> >> -- >> Vic, K2VCO >> Fresno CA >> http://www.qsl.net/k2vco/ >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html > > > -------------------------------------------------------------------------------- > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.872 / Virus Database: 271.1.1/3331 - Release Date: 12/22/10 > 02:34:00 > -- Vic ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
