One thing I don't like about doing different things with tubes is there is no real info on running 813's triode connected. What's the distortion values?
I have a Gonset G76 that uses zero bias and drives the screen grid of a pair of 6dq6 tubes as modulators. I don't think its real clean. Brett N2DTS -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Patrick Jankowiak Sent: Tuesday, October 12, 2004 6:31 PM To: [email protected] Subject: Re: [AMRadio] Mod xmfr Ahh yes. The class-B 813 modulator. Glad to see it! I'd like to comment about it from an audio standpoint as I have done this for audio with 807's. I don't know how tough the 813 control grids are. I would suggest using some resistors to limit the current to the modulators' control grids to about 15 mA average (suggested based on the class C conditions in the tube manual; 20K worked for for 807's but the drive voltage was much less). It is really the screen grids that must be driven to get the plate current up. The peak screen voltage may also be as much as 750 volts (1500 g-g) for the 813 (the same value as the G2 DCV would be if it were operating AB1). An old audio output transformer from a tube amplifier makes a good driver transformer because it will stand the voltage well. The author might have some suggestions too. Patrick From: "Jim Wilhite" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Mod xmfr Check here: http://www.amwindow.org/tech/htm/813/813.htm ______________________________________________________________ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected]
