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 Post subject: Designing bench ABC eliminator, What outputs required?
PostPosted: Dec Wed 13, 2017 4:22 pm 
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Joined: Jan Fri 20, 2017 9:36 pm
Posts: 55
Location: Centuria, Wisconsin
I am in the process of designing a bench battery eliminator for the ABC voltages. After researching the available eliminators, and suggestions listed on this site, I have some idea of how to proceed. It appears that the A supply should be adjustable from about 2 volts to at least 6 volts with a current rating up to at least 2 amps. The B supply appears to range from 22.5 up to 135 volts (in steps of 45 volt batteries with taps at 22.5 volts). So far, I have only run across radios that use 135 or 90 volts, and was wondering if the other voltages (45, 67.5, 112.5) are ever used?Also, on the C voltages, most cover the range of 3 to 22.5 volts. Since these batteries were usually 4.5 volt batteries with taps at 1.5 and 3 volts, what is the highest voltage needed? I question the ranges I found, as I have a RCA 84BT that has a connection to the 1.5 volt tap on the 4.5 volt battery. Was the bias voltage ever above 9 volts (2 batteries)? It may be necessary to broaden the range to allow for future radios? I know that some will say "why not just use batteries for the C supply since basically no current is required"? I figure that since I am only in the design stage that I may as well incorporate as many possibilities as I can into one piece of equipment.

Any comments or suggestions would be appreciated.

John


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 Post subject: Re: Designing bench ABC eliminator, What outputs required?
PostPosted: Dec Wed 13, 2017 4:44 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 26895
Location: Detroit, MI USA
It totally depends upon exactly what sort of radios you intend to use the supply with.

For example, portable sets and farm sets sometimes had A battery voltages of 1.5, 7.5, or 9 volts so your filament supply needs to have more range than you think. And I would want the current rating a bit higher than 2 amps to give a little margin on some early battery powered home sets.

Those portables also sometimes used a 67.5 volt B battery and IIRC there may have been some pocket sized portables that used a 45 volt B battery.

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 Post subject: Re: Designing bench ABC eliminator, What outputs required?
PostPosted: Dec Wed 13, 2017 4:44 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7312
Location: Bossier City, Louisiana
If your refering to a twenties battery set, Antique electronic supply sells a decent kit at a fair price. I utilized one as my bench supply for years. Otherwise utilize the search function on this site you will find MANY threads on the subject.

https://www.tubesandmore.com/products/kit-power-supply

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 Post subject: Re: Designing bench ABC eliminator, What outputs required?
PostPosted: Dec Wed 13, 2017 5:06 pm 
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Joined: Jan Fri 20, 2017 9:36 pm
Posts: 55
Location: Centuria, Wisconsin
I plan to limit my collection of battery radios to the 30s to early 40s. I used to design special test equipment for production testing of the product where I worked, so sort of miss it. Retired in 2010 and am just now seriously starting to look at some of the radios I have collected over the years. So far, just a few are the old "farm radio" category, but I want to allow for any future requirements. A lot of the enjoyment is designing and building the test equipment that I will be using.

Thanks for the suggestions.
John


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 Post subject: Re: Designing bench ABC eliminator, What outputs required?
PostPosted: Dec Thu 14, 2017 2:22 am 
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Joined: Feb Tue 10, 2009 3:16 pm
Posts: 682
Location: zipcode 46235
Then there are the 2v farm radios, made before the introduction of the 1.5 volt bantam tubes. B voltages go from 67.5, 90 and 135 volts. They usually had a HUGE B-C battery and a large air cell battery.


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 Post subject: Re: Designing bench ABC eliminator, What outputs required?
PostPosted: Dec Thu 14, 2017 2:37 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: SoCal, 91387
Some '30's farm sets needed a single supply of 32 volts, @ 2+ amps. My Zenith farm sets each require 6 volts, also at 2+ amps, so that leaves out dry batteries as a supply source.

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 Post subject: Re: Designing bench ABC eliminator, What outputs required?
PostPosted: Dec Thu 14, 2017 3:43 am 
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Joined: Jun Wed 21, 2006 1:56 am
Posts: 914
Location: Katy, Texas
Some late 20s sets will call for 180. I no you said 30s & 40s but ya never know what you will run across.


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