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 Post subject: Modern Low plate voltage substitutes for antique tubes ie. 2
PostPosted: Nov Mon 12, 2018 5:26 pm 
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Joined: Nov Tue 29, 2016 6:05 am
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Location: Burnaby BC Cda. V5E 4A6
hi
Looking for a modern tube that can replace a 201A and work at a lower safer and lower cost power supply(s)
Using three low-cost wallwarts for Plate, Grid, and Filaments.
Hopefully in the 12XXX family used in vintage Automobile Radios and or the 1.5 volts families used in vintage portable radios. The plan is to use dead 201 tube bases as an adapter so no need to mess with the wiring
thanx
73 de jordan ve7jjd


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 Post subject: Re: Modern Low plate voltage substitutes for antique tubes i
PostPosted: Nov Mon 12, 2018 7:44 pm 
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I think a 30 tube would work, but different filament voltage..


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 Post subject: Re: Modern Low plate voltage substitutes for antique tubes i
PostPosted: Nov Mon 12, 2018 8:44 pm 
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Location: Ohio 45177
You are right, some mini and submini use low power DC filaments and can work at like, 45 or 67 Volts, not too dangerous but not carefree, either. I thought those car radio tubes were very high impedance output or something? I suppose the much higher gain of more modern triodes, let alone pentodes, can cause issues sometimes. 201 is a low Mu tube, very low.

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 Post subject: Re: Modern Low plate voltage substitutes for antique tubes i
PostPosted: Nov Mon 12, 2018 10:24 pm 
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Those space charge tubes use 1 amp of filament current each. The power output is only a few hundred milliwatts also. Power transistors were used in the output stages since they could handle more power at low voltages, but they weren't very good at higher frequencies.

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 Post subject: Re: Modern Low plate voltage substitutes for antique tubes i
PostPosted: Nov Mon 12, 2018 10:34 pm 
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Joined: Dec Thu 31, 2009 4:28 pm
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Location: Under the Blue skys of OR 97524
You might like these. Not a direct answer, but, there are other issues with tube substitution re:201As:

https://www.russoldradios.com/blog/no-substitute

https://www.russoldradios.com/blog/reml ... bstitution

P.S. I was running a Westinghouse RC the other day with only 9V on all 3 plates. It worked great. The tube you are looking for might be the one you already have.

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 Post subject: Re: Modern Low plate voltage substitutes for antique tubes i
PostPosted: Nov Tue 13, 2018 12:43 am 
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Russ,

Would you mind posting the pin-outs of the tube adapters for the various types of substitutes?

Best!

Chas

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 Post subject: Re: Modern Low plate voltage substitutes for antique tubes i
PostPosted: Nov Tue 13, 2018 3:39 am 
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The low voltage, almost low Mu triode, 12AE6 used the 6BF6 as the basis for design. I've used a 12BF6 for 12AE6 and could tell no difference. If one doesn't mind using 12v for tube heater(and maybe B+) the Lo Mu(7.4) 12FK6 may work.

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 Post subject: Re: Modern Low plate voltage substitutes for antique tubes i
PostPosted: Nov Wed 14, 2018 5:00 pm 
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Joined: Dec Thu 31, 2009 4:28 pm
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Location: Under the Blue skys of OR 97524
Chas wrote:
Russ,

Would you mind posting the pin-outs of the tube adapters for the various types of substitutes?

Best!

Chas


I just used the base diagrams in the RCA tube manual. Except for one of the versions I made it is just a 1 for 1 connection - plate to plate connection and so on.

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