I use a pair of them in my TMC GPT 750 as modulators with 3kv on the plates.
They work very well, and are easy to drive. I use a simple zener diode scheme in the filament transformer centre tap ground return for biasing the tubes to idle at about 50 ma per tube. The tubes/sockets are relatively inexpensive for their capabilities, and available new sources like RF Parts on the net. 73 Al Santangelo VE3 AJM Patrick Jankowiak wrote: > After buying several 304TH's and 304TL's, and out of five, > finding only one to be good, I'm pretty sick of it. I don't know > why I seem to end up with all the duds, but it's pretty frustrating. > > -one had half the filament out > -two had a filament to grid short > -one flashes over at 500V plate voltage > > I am thinking about the 3-500Z as a modulator. Any comments from > the wisdom here? > > At least I can buy them new and they will have a warranty. > > I suppose sockets, anode dissipators, chimneys, and chimney > hardware can't go bad, so I can't really get ripped off there.. > > Does anyone have a couple sets of 3-500Z socket/chimney/hardware > they'd be willing to sell? > > Looking for: > > -two SK410 / SK410S or equivalent air system sockets > -two HR-6 (0.6" tall) heat dissipating connectors > -two SK406 chimneys and clips for the chimneys > -Pamotor 2000 or 6500 or equivalent blower that will do 13CFM at > 0.1" pressure or better > > I also have a commercial RF deck with six extremely good 4CX250B > tubes and blower (it's actually a puse amp) I would trade, for > the above and a -guaranteed very good pair- of 3-500Z's. > > http://208.190.133.201/ifi400/ifi400.html > > Thanks, > Patrick > _______________________________________________ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
