UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - AZ31 as rectifier for a stereo Mullard 3-3?

qualityten · 16th May 2021, 10:03 pm

I completed the construction of this stereo 3-3 over the weekend and it's working fine. If I remove the inputs, it goes into HF oscillation, but I haven't looked at the feedback yet.

Just to complete the rectification discussion, with the EZ81, and no limiting resistor, the voltages at the HT capacitors (C9, C6 and C3) are about 20V lower than the Mullard schematic. The EL84 anode voltage is 15V lower and screen grid voltage is 23V lower. The EL84 cathode voltage and the EF86 anode and screen grid voltages are exactly as specified.

So, it's working okay, I think, but I would need to move to solid state rectification to get closer to the schematic. All this is noted in various contributions to this thread. Thanks to all, and especially for saving me from using the AZ31.

16th May 2021, 10:03 pm	#25
qualityten Octode Join Date: Feb 2009 Location: Wallasey, UK. Posts: 1,314	Re: AZ31 as rectifier for a stereo Mullard 3-3? I completed the construction of this stereo 3-3 over the weekend and it's working fine. If I remove the inputs, it goes into HF oscillation, but I haven't looked at the feedback yet. Just to complete the rectification discussion, with the EZ81, and no limiting resistor, the voltages at the HT capacitors (C9, C6 and C3) are about 20V lower than the Mullard schematic. The EL84 anode voltage is 15V lower and screen grid voltage is 23V lower. The EL84 cathode voltage and the EF86 anode and screen grid voltages are exactly as specified. So, it's working okay, I think, but I would need to move to solid state rectification to get closer to the schematic. All this is noted in various contributions to this thread. Thanks to all, and especially for saving me from using the AZ31.