So far I have only played with nimble, fragile, low-current, point-contact germanium diodes. The "neovintage" power supply of the register set requires higher current than their usual 20 to 40mA rating.
I got some OA31 from the usual suspect (minifux1) (who provided, among others, essential parts for #Germanium ECL) and they are pretty impressive: rated at 85V reverse voltage, or 3.8A in direct current. Germanium hates the heat (it leaks a lot and the junction should not exceed 85°C usually) so the bulky metal package says we're doing serious business here.
I measured the I/V curve with a crude setup and I'm rather impressed :-)
|Direct current (A)|| Voltage drop (V)|
The curve is quite flat and the drop is lower than silicon diodes and comparable to a good Schottky ! This is a significant progress compared to selenium rectifiers ;-) and the performance for the low-voltage diode bridge will be great :-)
I expect a Vpeak of 4.3V at the output of the transformer (conservative estimate). The diode bridge will "eat" 2×0.45V=0.9V, make this 1V. The diode bridge peak will be at least 3.3V, better than the previous estimate of 2.9V :-)
These measurements were done "cold" and are expected to vary with temperature. Not in a bad way, though, because the drop would be slightly reduced. I don't expect the diodes to require a heatsink because they would dissipate an average of 0.5W and they are already pretty bulky.
As previously noted, this could be tested with loads made of many 39 ohms resistors in parallel.
But wait, I also received several AY105K ! They are a little bit smaller and are rated for 5A (a different source claims 3A, which is a convenient margin)
It's another contender for the diode bridges. Those vintage Italian diodes are smaller and have a more convenient packaging with insulated heat spreader !
However the drop is higher than the OC31 : 0.5V at 1A only, and 0.59V at 1.5A. I would use them for the other power supplies, where the rails are higher voltage (12V ?) and slightly lower current.
I also expect to receive a few Д305 for comparison. They are claimed at 10A so they should be impressive, though I won't have enough to make more than one bridge. So far the OA31 is the clear winner :-)