10-30-2010, 06:22 AM
Great to hear she's workin' like she should. You may want to consider hiding a small 1/8 phone jack hooked you so you can switch between the cartridge and another input. I did it to the radio in my 1961 Ford. Now I can plug it in and listen to MP3's of old radio shows or unplug it and it reverts back to the AM BC band. The radio is kinda of an odd ball as it uses some 12v tubes with 12volts B+ and a transistorized (oophs I said a bad word) output stage. So I too used a 120v/24v transformer to drive the tube input stage. Without it the MP3 player couldn't make enough audio to drive the audio stage to full output and at max it was distorted.
One of the reasons I mention the phone jack is that it seems that Philco didn't have many sets (if any) that have a phono input. The RP-42-2 has a good design. Most phono oscillators back that where powered right off the ac line with a resistor line cord and without a power transformer (ac/dc style). Having a power transformer is good for a few reasons. Eliminates shock hazard from having the ac line tied to the metal chaiss. Makes it easy to hook up other inputs cause you don't have to figure out what's hot with 120vac. And having the transformer it helps stabilize the dc high voltage this in turn helps the oscillator from FMing (causing the output frequency to shift with the level of audio applied to grid of the osc tube, not amplitude that's what you want) FMing will make the audio sound distorted.
Terry
ps If you are cheap like me and like experimenting you could try building a small fet (another bad word) preamp. Could do it for a dollar or two in parts to up the output of your cartridge.
One of the reasons I mention the phone jack is that it seems that Philco didn't have many sets (if any) that have a phono input. The RP-42-2 has a good design. Most phono oscillators back that where powered right off the ac line with a resistor line cord and without a power transformer (ac/dc style). Having a power transformer is good for a few reasons. Eliminates shock hazard from having the ac line tied to the metal chaiss. Makes it easy to hook up other inputs cause you don't have to figure out what's hot with 120vac. And having the transformer it helps stabilize the dc high voltage this in turn helps the oscillator from FMing (causing the output frequency to shift with the level of audio applied to grid of the osc tube, not amplitude that's what you want) FMing will make the audio sound distorted.
Terry
ps If you are cheap like me and like experimenting you could try building a small fet (another bad word) preamp. Could do it for a dollar or two in parts to up the output of your cartridge.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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