Tnx Don, Makes sense... but I have the 'feeling' that by connecting a pentode/tetrode as a triode you get something other than a triode...
As in none of the above... something 'different'... with a 'nature' all of its own... Right/wrong??? 73 Vince ka1iic -.--. On Fri, 5 Jul 2002, Donald Chester wrote: > > > > >From: <[EMAIL PROTECTED]> > >...I've been looking up all the info I > can get about using 807's in triode >connection.... > > >First off the older ARRL handbooks show connecting the grid to the > screen >through a 20k ohm resistor and driving the screen... > > That makes the tube act like a high-mu zero-bias class-B triode. > > > >Another publication shows connecting the screen to the plate > directly and >driving the grid as you normally would... > > >And case three shows connecting the screen to the plate through a 100 > ohm >resistor and driving the grid as per the norm... > > That makes it act as a low-mu triode, and reduces the plate > resistance. This would be mose useful to drive a loudspeaker or to > use to drive a class-B amplifier stage. It would require considerable > negative grid bias and would be less desirable as a class-B amplifier. > > The 100 ohm resistor could be to stop parasitics or to reduce the > "dynatron" effect, in which there is a kink in the characteristic > curve that results in a negative resistance effect, and can cause > intermittent oscillation and distortion over part of the audio > waveform. > > Don K4KYV
