For Patrick, I use the same tube compliment: 4X1 with the 304TLs. As far as the 4X1 screen goes... I use a huge choke, just because I had it available. 500VDC. I see the screen current bounce up from 130 ma to 175 ma approx during modulation on the typical Simpson current meter. The signal reports are "clean audio". I would keep it simple. The second transformer is probably going to give different phase relationship. The screen inductor should be more "in-step" with a mod transformer... if big enough. FYI, I use the stancor polypedance 600W mod transformer with the same heising connection you have also, and floated the xformer iron from ground to prevent arc-over to ground. The xformer still talks back a bit. Man those 304TLs put out some audio!!! Great tubes. Very high plate current capability before saturation. George AB2KC
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of patrick jankowiak Sent: Sunday, November 30, 2003 2:39 AM To: [email protected] Subject: [AMRadio] Modulation of the screen grid Would anyone mind looking over the schematic at the web page below and see if I am on the right track to modulate the G2 voltage of a 4-1000? This should provide the 250 volt peak voltage necessary for the screen grid, and then I won't have to rely on using just a choke from the screen supply or a dropping resistor. Basically I plan to use a smaller mod xfmr to couple some of the modulated plate voltage to the screen. Maybe I have some mistakes in the parts or signal level values, but I think it should be right. Thanks in advance, Patrick http://208.190.133.201/mod001.gif _______________________________________________ AMRadio mailing list [email protected] http://mailman.qth.net/mailman/listinfo/amradio
