Posts: 1,118
Threads: 21
Joined: Jan 2014
City: Wellborn Florida
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.
Posts: 35
Threads: 2
Joined: Dec 2023
City: Seaford
State, Province, Country: DElaware
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/lm...calculator
The process of learning is to fix something that is not broke.
Posts: 1,118
Threads: 21
Joined: Jan 2014
City: Wellborn Florida
some info about voltage regulators
https://www.youtube.com/watch?v=IjJWWGPjc-w Also a 3 amp voltage regulator
(This post was last modified: 01-17-2024, 09:08 PM by
David.)
Posts: 35
Threads: 2
Joined: Dec 2023
City: Seaford
State, Province, Country: DElaware
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
The process of learning is to fix something that is not broke.
Posts: 35
Threads: 2
Joined: Dec 2023
City: Seaford
State, Province, Country: DElaware
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
The process of learning is to fix something that is not broke.
Posts: 855
Threads: 8
Joined: Jul 2020
City: Greenlawn
State, Province, Country: NY
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.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
Posts: 855
Threads: 8
Joined: Jul 2020
City: Greenlawn
State, Province, Country: NY
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.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
