<VV> Re: Was Pertronix, Now Space Charged Tubes

JVHRoberts at aol.com JVHRoberts at aol.com
Sat Oct 29 14:36:17 EDT 2005

OK, SOMETIMES my memory and the facts do get confused. I found a 1960  
Corvair radio in my heap, looked at it CAREFULLY. It would appear you are right.  
Still, I remember a vibrator in that 1961 radio from years gone by... 
So, not to proud to admit my error... 
So, how much crow do I have to eat? Pass the hot sauce... <G>
In a message dated 10/29/2005 1:34:20 P.M. Eastern Standard Time,  
JVHRoberts at aol.com writes:

Yes, the  first two digits are heater voltage ONLY. 
And there ARE tubes that can  produce enough power in the output stage, but  
NOT without a  transformer! 
As far as wattage goes, Ohm's law to some extent is at work  here. If you  
only have a few mA, you'll need LOTS of voltage to  deliver the wattage. 
tubes LOVE voltage. That's where they  work the best. 
It would be interesting to take a modern DVM through a tube  Corvair radio  
chassis and measure plate and grid voltages, since  that's where the voltage  
really is. I do recall seeing a '61 radio,  and it had a tiny little 
looked like a capacitor....  Needed a stethoscope to hear the whine...

In a message dated  10/29/2005 12:34:34 P.M. Eastern Standard Time,  
corvairduval at cox.net  writes:

_JVHRoberts at aol.com_ (mailto:JVHRoberts at aol.com)   wrote:

Keep in mind those first two digits refers ONLY to the  filament heater  
voltage. ALL stock tube radios for cars still had  vibrators, and still  
needed MUCH 
higher than 12 volts to the plates  and cathodes to work  properly. 
The reason some used a transistor  output was cost. It eliminated the  need 
for a relatively expensive  output transformer, since tubes are high  
and transistors  handily drive low impedance loads with significant  power 
12  volts. 
So, inside of that 'space age' radio, are still some pretty  good  voltages, 
usually over 100 volts. 

In a  word, NO.  Check  the RCA Receiving Tube Manual and you will see the  
following tubes were made  with plate voltages of 12.6 volts.   Cathodes in 
radios run near 0.0  volts. :
12AC6, 12AD6, 12AE6,  12AE7, 12AF6, 12AJ6, 12AL8, 12BL6, 12CN5,  12CX6, 
12DL8,  12DS7, 12DU7, 12DY8, 12DZ6, 12EA8, 12EC8, 12EG6, 12EK6,  12EL6, 
12F8, 12FK6, 12FM6, 12FR8, 12FX8, 12GA6, 12J8, 12U7.

None  of  these could produce power for audio output stage. Most run 1 or 2 
plate  current. One was rated at 35 mA, but that is less than a 1/2  watt. 
will  not see a vibrator in a Delco Corvair radio, but you  will see tubes in 
1960,  1961, and 1962. No hidden batteries, no  multivibrator circuits to 
step up  transformers. No "high"  voltage. The other car lines were also 
Space  Charged tubes in  the early 60's, like Ford/ Philco.

Tony, feel free to  step in  here.

Frank DuVal


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