Phonola amp question

Thom · by **Thom** » Wed Nov 26, 2008 4:53 pm

I'm rebuilding a 1961 Phonola portable with a one-tube-wonder amplifier that is fed a signal from a crystal cart, flip over style Astatic 108v that did put out around 1.0 to 3.0 volts near as I can tell. The cart is dead and putting in a newer lighter tracking 0.5v cart (which is what I was hoping to do) is going to result in a rather weak output. I know others have been in the same situation and I was wondering how you got around this problem. The amp uses a 25L6 Beam-power tetrode tube and a selenium half-wave rectifier which I may replace with a diode. Happy Thanksgiving. Thom

Thom · by **Thom** » Fri Nov 28, 2008 4:58 pm

Turns out I had a 2.50v cart in stock so I'm not going to bother trying to convert this one. I'm going to experiment a little though down the road.

Record-changer · by **Record-changer** » Mon Dec 01, 2008 1:01 am

A silicon rectifier is not a direct replacement for a selenium rectifier, because the selenium rectifier has a high forward voltage and an internal resistance. If these are not included in the replacement circuit, the rest of the device may fail.

Thom · by **Thom** » Tue Dec 16, 2008 12:52 pm

What was I thinking? Thanks for the heads up. I didn't bother replacing anyway because it works fine.

Thom