Philco 40-95 Farm Set - Printable Version

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RE: Philco 40-95 Farm Set - David - 01-13-2024

In the 19 century you could find AC an DC power. The last of the Edison DC system went away in New York City around 1980? The US power grid inter connect got under way after WWII. Before you would find 25Htz, 30Htz, 40Htz, 50Htz, an 60Htz. Many small towns would run the generator at a slower speed so as to save wear an tear on the system. In South America better take a volt meter. In Japan the islands in the south are 50Htz at 100 volts. If you take a 2 pole generator running at 3600 rpm you get 120 volts AC at 60Htz. Slow it down to 3000rpm you get 100 volts at 50Htz. So at the end of WWII the islands were using US military stuff to make power. So some electricity is better than none.

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RE: Philco 40-95 Farm Set - 7chip7 - 01-17-2024

I got my LM317 regulators yesterday (25 of them), now I can finish building my 1,5 voltage source power supply. I found a good online 317 resistor calculator see the link here
https://circuitdigest.com/calculators/lm317-resistor-voltage-calculator

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RE: Philco 40-95 Farm Set - David - 01-17-2024

some info about voltage regulators  
https://www.youtube.com/watch?v=IjJWWGPjc-w     Also a 3 amp voltage regulator

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RE: Philco 40-95 Farm Set - 7chip7 - 01-18-2024

I wired up a LM317 Power supply and did a smoke test by hooking up to the tubes in the radio, I adjusted the voltage for 1.5 DC, the tubes were drawing a little more than 200 ma, so it seems to be correct.
I checked out the links you sent and thanks Dave, great info on voltage regulators . I will post some more as I continue along
Regards Chip

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RE: Philco 40-95 Farm Set - 7chip7 - 01-19-2024

This morning I wired up the audio section of the radio, I hooked it up to the battery eliminator and I could hear the typical amplifier hum and the volume control worked very well. The B+ voltage was reading around 82 volts and the A voltage reading was stable at 1.5 volts. I am going on to the IF section and test the 455kc transformers. Will keep posed.
Chip

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RE: Philco 40-95 Farm Set - MrFixr55 - 01-27-2024

If I stated 30V farm sets, my bad. A couple of RCA tubes (Like the "48") were rated at 30VDC, but yes, many Delco farm power generators were rated for 32VDC.

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RE: Philco 40-95 Farm Set - MrFixr55 - 01-27-2024

Chip, re your question about B-, note that B- does not connect directly to ground. It connects through a resistor to ground and via another resistor to the grid of the Audio Output tube. this is to provide the required grid bias, instead if using a "C" battery like older farm sets (like my RCA 5BY and 6BT) with more audio power did. Note that A- does connect to chassis ground. I don't think that the relatively small mismatch is gong to make much difference.

Congrats on your progress so far! Keep plugging along. I wouldn't remove the engraved plate from the radio. While not original, it is part of its history.

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