#16
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Not rocket surgery.. 201 has a 5V 1A filament, 201A is 5V .25A. So, (assuming a standard 5 tube radio) you'd need 5A capable supply form running 201's, or 1.25A capable supply to run the 201A's. You might try swapping the tubes to different positions and check performance. We used to put the weakest tube in the "detector" position.
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#17
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***UPDATE***I received the 6V 20amp battery and, lo and behold, the set plays great. It proves that these sets with these early tubes needed plenty of kick from their batteries! In conclusion as to what was needed to run my RC with the non-A UV tubes: 1 UV-200 tube (det.) 2 UV-201 tubes (amp) 1 6V/20amp multi-purpose lead-acid battery (A supply) 1 ARBE III battery eliminator (B supply det-22, amp-45) #12 gauge wire Here's a pic of the non-A's blazing away. It's quite a sight and so cool to see the set playing the way it did in '22! Last edited by decojoe67; 11-25-2016 at 09:56 AM. Reason: add photos |
#18
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Those puppies are really bright! And I'm sure folks took advantage of that light source back in the day.
One very important point missing from the previous discussions is that all batteries have an equivalent internal series resistance. It's roughly based on the chemistry and the physical size of the plates. But in general a lower AH capacity battery would have more internal resistance than a larger one of the same construction. It's this internal resistance that is the real reason your voltage was pulling down more so when you tried the smaller AH capacity batteries. Based on ohms law(V/I=R) if your battery voltage was being pulled down 1.5 volts under load, you'd divide 1.5 volts by 3 amps, which gives an equivalent internal series resistance of .5 ohms. If you pull even more amps through that same .5 ohms then you'll have a proportionally larger internal voltage drop. Hope that all makes sense. |
#19
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#20
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Some of the early (IIRC wet cell) 'A' batteries were basically car batteries of the time marketed as radio batteries...There were stores that had charging stations for them.
Ever wonder why 6.3V and 12.6 became common heater voltages?....Well they did it so common automotive batteries could power the power hungry filaments/heaters of early tubes.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
Audiokarma |
#21
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Those filaments look very bright... I hope that you are not exceeding the 5 volt specification by turning the rehostats up too far with the new battery, which will severely shorten tube life. Can you measure the filament voltage?
jr |
#22
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#23
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Additional info, using higher B+ and bias battery for more output.
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#24
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The non-A tubes' filaments were non-thoriated and ran that bright by design. The 'A' tubes' thoriated filaments could run much cooler at 1/4 the amperage
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#25
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Very interesting. Thank you. As a collectible the set just has so much more charm viewing the bright tubes through the sets peep-hole. I got so much volume I actually had the amp rheo turned down. I also noticed an improvement dropping the B+ amp from 90 to 45. Another member had recommended that to me and he was right.
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Audiokarma |
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