Adding switchable ss rectifier to 18watt

[solow1977]

How hard would it be to add a ss rectifier, like in the 20 watt. to the 18 watt. Wouldn't it be a switch and some diodes?

[Igbit]

Depending on what you're trying to do, you might have to add either some voltage dropping resistors or diodes to match the SS rec's output to that of the tube rec. SS output is typically higher.

[abro162]

Very easy - get a dpdt switch, connect the ac voltage from the transformer to the centre poles of the switch, then you have your top two poles supplying voltage to the 2 ez81 pins in one position, with the bottom two poles just connect a diode to each and join them to the stand by switch like a standard rectifier (so you now have 2 wires running to the stby switch).

Not sure if this is bad for the ez81 when running the diodes with the standby closed - you will have a high voltage on the cathode of the ez81 and no voltage on the plates. But this is how I did it in my 5e3.

HTH - watch out for higher voltages with S-S rectifier

[daschnoz]

I would connect the AC to both the diodes and the tube rec. The selection switch would choose between the rectified voltage from the tube or the SS diodes. The diodes could handle it, but I'm not sure what a tube rec would do with high voltage on the cathode, and no voltage on the plates.

[Jwalker]

Groove tubes makes a plug in ss replacement for the ez81.

[rjgtr]

Weber makes a copper cap without the sag, but with the turn on warmup time. I would get this before any other kind of plud in replacement. Even though I've seen diagrams for switchable rectifiers, it isn't good to switch while the amp is on! So a plug in replacement is probably the safer way to go.