A good proportion of the NOS tubes are warehoused in central Florida. I hope Irma is not TOO angry!! Please, please Irma, go far far away. Like N-K.
I just had this funny idea, if Florida were covered with windmills, maybe we reverse the power grid and blow Irma away. Next Sci-Fi horror movie maybe.
I just had this funny idea, if Florida were covered with windmills, maybe we reverse the power grid and blow Irma away. Next Sci-Fi horror movie maybe.
Good Morning, Y'all:
First, the good news, just placed and got acknowledgement for an order with ESRC in Orlando, apparently all is good with them. Oh, and it's for the tubes and sockets needed for this project.
OK, on the continuing saga of how in the world will I get to spend quality time with this project... It looks as if it will continue to be bits and pieces here and there. Had no idea how full my plate was until trying to come up with a block of time for this. Not complaining that much, being busy beats the alternative!
Been thinking about the driver and output stages and what if any inherent PSRR they have. Remembering that the driver is a full differential, and that one plate is supplied directly from the B+ while the other is supplied from the plate of "normally" configured output tube, it took some doodling and thinking to come to the conclusion that this part of the circuit is no more nor less sensitive than in a common PP arrangement. The differential output of the stage is immune to PS noise but the common mode is not. This means to me that common mode will couple to the grids of the PAs and it seems will disrupt at least quiescent conditions. A negative going noise impulse on the B+ will push the PA grids more negative, a positive going pulse does the opposite. The proper differential drive signal will still appear but the bias has been dynamically disrupted.
This applies to the P-S and to the standard PP topologies. The B+ feeding the driver should be clean. I am going to post regulate the feed to the drivers and PI stages, and make sure the negative supply is super clean. Easy with today's devices, not so much back in the days of the development of these circuits. Could be why some of these never succeeded, not because the circuits were inherently flawed but because the required housekeeping supplies were not very good without spending a ton of money.
Moving on to the output stage itself, cancellation of B+ noise is a well known and accepted attribute of PP stages. And so it is, stands up to scrutiny.
At first glance, the P-S (or SEPP as some folks have urged me to say instead), a cancellation mechanism is not immediately apparent. But I believe it it present. The doodles show that whatever is happening to one of the tubes as a consequence of, say, ripple on the B+, is also happening to the other, with the result of zero net differential change on either coil, thus no change in output.
If one draws the single coil P-S, it is immediately obvious that there is full cancellation. The only caveat is that both of the stacked supplies must be doing the same thing at the same time. Can be another argument in favor of the split primary since a single supply is used.
Anyway, just some food for some thought, I really need to win the lottery and retire from my professional work. Then I can finish building my airplane and this amplifier
Rene
First, the good news, just placed and got acknowledgement for an order with ESRC in Orlando, apparently all is good with them. Oh, and it's for the tubes and sockets needed for this project.
OK, on the continuing saga of how in the world will I get to spend quality time with this project... It looks as if it will continue to be bits and pieces here and there. Had no idea how full my plate was until trying to come up with a block of time for this. Not complaining that much, being busy beats the alternative!
Been thinking about the driver and output stages and what if any inherent PSRR they have. Remembering that the driver is a full differential, and that one plate is supplied directly from the B+ while the other is supplied from the plate of "normally" configured output tube, it took some doodling and thinking to come to the conclusion that this part of the circuit is no more nor less sensitive than in a common PP arrangement. The differential output of the stage is immune to PS noise but the common mode is not. This means to me that common mode will couple to the grids of the PAs and it seems will disrupt at least quiescent conditions. A negative going noise impulse on the B+ will push the PA grids more negative, a positive going pulse does the opposite. The proper differential drive signal will still appear but the bias has been dynamically disrupted.
This applies to the P-S and to the standard PP topologies. The B+ feeding the driver should be clean. I am going to post regulate the feed to the drivers and PI stages, and make sure the negative supply is super clean. Easy with today's devices, not so much back in the days of the development of these circuits. Could be why some of these never succeeded, not because the circuits were inherently flawed but because the required housekeeping supplies were not very good without spending a ton of money.
Moving on to the output stage itself, cancellation of B+ noise is a well known and accepted attribute of PP stages. And so it is, stands up to scrutiny.
At first glance, the P-S (or SEPP as some folks have urged me to say instead), a cancellation mechanism is not immediately apparent. But I believe it it present. The doodles show that whatever is happening to one of the tubes as a consequence of, say, ripple on the B+, is also happening to the other, with the result of zero net differential change on either coil, thus no change in output.
If one draws the single coil P-S, it is immediately obvious that there is full cancellation. The only caveat is that both of the stacked supplies must be doing the same thing at the same time. Can be another argument in favor of the split primary since a single supply is used.
Anyway, just some food for some thought, I really need to win the lottery and retire from my professional work. Then I can finish building my airplane and this amplifier
Rene
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