Hi Steve, What's the finals on that rig, 813's? I think I have a rig just like that here. Can you describe the rig? Is a schematic available?
TIA, 73, Ed, VA3ES > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of > [EMAIL PROTECTED] > Sent: Tuesday, March 15, 2005 9:25 AM > To: amradio@mailman.qth.net > Subject: [AMRadio] Mike > > > Thanks Guys: > > This mike is for a vintage 1948 AM rack rig homebrew by W2PLY > who moved into Senior Residence. > The speech amplifier/modulator schematic is right from August > 1947 QST. > > I got the rack and the 5 sections directly from the flat bed > trailer at the estate sale...and now just about finished > doing what very little fixin required. > > The article cites a crystal mike; it feeds directly into the > grid of a 6SJ7 with no grid leak resistor. > > As I understand these things, the mike - what type of > cartridge - needs to put out 'so many' microvolts necessary > for the tube into which it feeds. > > And the impedance needs to 'match'. > > I understand there plenty of gain after the 6SJ7...and one of > the 6SN7's has a "tone control" potentiometer in the grid. > > Personally, my voice is a little higher from center in > pitch..and I'd prefer more lower than higher freq. > response...which is generally a problem due to low freq. > rolloff in the mike curves...that's why I'm eager to try this > 'tone control'. > > I guess the first question is: what impedance number is > required for a 6SJ7 grid? > > Your generous help is always appreciated. > > Regards, > Steve > WA2TAK > ______________________________________________________________ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net >
