HI Hue

Sorry for the late reply.

I'm blessed to have some friends that keep their eyes out for tuning knobs!

The HP-23 provides 250V B+.  For my full up SCR-274N setup, I use the same HP-23 but have a 1K 10W resistor in line to drop the voltage to about 190 to 200V.   I'll do that for this setup when I find some time.

The Blue Box under the HP-23 is my 28V supply.   I got it at an estate sale for $20. It was originally a 12V supply, but it was nicely constructed and had dual metering.   I replaced the 12V transformer with a 28V transformer and added a regulator and pass transistor. I think I can source 5A from it, but in any case it is more than sufficient for any ARC-5 (generically speaking) receiver.   I have the output filtered, and it's pretty clean.

The box under the headphones is a Timewave DSP-599zx noise filter / audio processor.  I"ve done what I call "iron man" listening -- no external audio processing -- and after doing it a few times I find it's much easier on the ears to be able to adjust the audio bandwidth down to 20 Hz.  By the way, the little blue box to its left is a Ratzlaff 7 Hz audio filter!    I've had to use it many times with my SDR or modern receivers.

73 Mark K3MSB