[Boatanchors] Tube filaments

[mac]

Maybe I'm missing something here but how  does having  5 volts wired  
to a type 80 rectifier socket prevent one from plugging a 45 (or 245,  
01A, 10, etc)  into it inadvertently or otherwise? The 45/245 had a  
2.5 volt filament, BTW.

Dennis D. W7QHO
Glendale, CA



On Dec 3, 2009, at 10:38 AM, Carl wrote:

> This came around in the just prior to the introduction of mass  
> produced AC
> radios of 1926-27. Earlier AC sets did not use a tube rectifier.
>
> The reason was to prevent anyone inadvertently using a receiving  
> tube in a
> rectifier socket. The 227, 245 and 280 both shared a 4 pin base for  
> example.
>
> When running 6V storage battery power and a vibrator the 280/80  
> could be
> left in place. Some farm radios could be run on 110VAC, 6 and 32VDC.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "David Knepper" <collinsradio at comcast.net>
> To: <boatanchors at qth.net>
> Sent: Thursday, December 03, 2009 12:33 PM
> Subject: [Boatanchors] Tube filaments
>
>
>> Does anyone know why RCA, etc. chose 5 volts for their rectifier  
>> tubes and
>> 6.3 volts for their receiving tubes?
>>
>> Just curious.
>>
>> Thank you
>>
>> David Knepper, W3ST/W3CRA
>> Publisher of the Collins Journal
>> Secretary of the Collins Radio Association
>> www.collinsra.com
>> Join today
>>
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