Hello all,
Gathering parts for my first scratch build. All Emission Labs DHT. EML 20B V4 IT coupled to EML 2A3 V4. Not sure what to do with the PS. I don't have the normal decreasing B+ from the output tube to the driver tube, it's just the opposite. Driver tube @ 420vdc, output tube @ 250 vdc. I've never seen an example of that scenario, and I don't have enough on the ball like you guys to know what issues may arise. I'll be using a star ground and taking great care to make sure the signal grounds don't get corrupted by the power tube grounds. So can I do a normal PS design w/ decreasing B+ after each section, picking off the driver tubes B+ first and then the power tubes last. I realize that the B+ for the driver will have to be super clean as I won't have any help from the power tube filtering. Or would this scenario be better served by two complete power supplies ?
as always, thanks in advance for any help
Cheers, Crazy Bill
Gathering parts for my first scratch build. All Emission Labs DHT. EML 20B V4 IT coupled to EML 2A3 V4. Not sure what to do with the PS. I don't have the normal decreasing B+ from the output tube to the driver tube, it's just the opposite. Driver tube @ 420vdc, output tube @ 250 vdc. I've never seen an example of that scenario, and I don't have enough on the ball like you guys to know what issues may arise. I'll be using a star ground and taking great care to make sure the signal grounds don't get corrupted by the power tube grounds. So can I do a normal PS design w/ decreasing B+ after each section, picking off the driver tubes B+ first and then the power tubes last. I realize that the B+ for the driver will have to be super clean as I won't have any help from the power tube filtering. Or would this scenario be better served by two complete power supplies ?
as always, thanks in advance for any help
Cheers, Crazy Bill
Yes, you'll need two separate supplies, one each for the output tube and driver.
Then you can better filter or regulate the driver. Think of all the power that would
be wasted trying to drop the 170VDC.
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i don't think it matter but noise increase as you approach the rectifying diodes
it is easy to derive a parallel power supply and add specific low current high filtering for the input tube voltage. i do this all the time for example tube heaters bias and misc.
it is easy to derive a parallel power supply and add specific low current high filtering for the input tube voltage. i do this all the time for example tube heaters bias and misc.
How about like this, gives two voltages and an iron not to expensive.
Mona
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Along the same lines, as the scheme Ketje provided, is an idea put forward by Pete Millett. A single CT winding can be configured to yield both a "tall" rail and a short rail. Bridge rectify the end to end voltage with either a 100% SS setup or a hybrid (SS diodes to ground) setup. The O/P of the bridge is the "tall" rail's "raw" DC. Connect the anode of an additional diode to the CT. Take the "short" rail's "raw" DC from the 5th diode's cathode.
Both rails are full wave rectified. The "short" rail is, in fact, a FWCT setup. In theory, the 5th diode can be omitted. Practice is definitely "another kettle of fish". For instance, "short" rail rise could be delayed by using a 5AR4, with its plates tied together, as the 5th diode.
Both rails are full wave rectified. The "short" rail is, in fact, a FWCT setup. In theory, the 5th diode can be omitted. Practice is definitely "another kettle of fish". For instance, "short" rail rise could be delayed by using a 5AR4, with its plates tied together, as the 5th diode.
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