pcan, richgwilliams, thank you for your suggestions!
I finally changed R16 from 1M to 47k. Removed R22. Changed R13 from 20K 2W to 22K 3W.
Moved a coupling cap little further away from heaters. And replaced shielded output wires with two twisted pairs. See attached picture.
I now have no hum, no EMI and no other interference. So no shielded needed!
I have also measured Vdc at the outputs (now with the inputs shorted) and values are normal. just a few mVdc.
Also, ripple at the outputs is non-existent.
I will take some measurements of THD and freq. response with my keithley 2015 and this app of mine: https://github.com/andmarti1424/free_keithley
May be tomorrow or next week. Will report back.
Thank you once again.
I finally changed R16 from 1M to 47k. Removed R22. Changed R13 from 20K 2W to 22K 3W.
Moved a coupling cap little further away from heaters. And replaced shielded output wires with two twisted pairs. See attached picture.
I now have no hum, no EMI and no other interference. So no shielded needed!
I have also measured Vdc at the outputs (now with the inputs shorted) and values are normal. just a few mVdc.
Also, ripple at the outputs is non-existent.
I will take some measurements of THD and freq. response with my keithley 2015 and this app of mine: https://github.com/andmarti1424/free_keithley
May be tomorrow or next week. Will report back.
Thank you once again.
Attachments
Start with 600 volt Cree rectifiers in HV power supply for up to 300 volts DC or 1200 volt Cree rectifiers for up to 600 volts.