How voltage sensative are tube radios?

I'm trying to get the original tube radio in the '50 Lincoln to work with the new (still + ground)12V system. I've got voltage reducers that will handle the amp draw just fine(only around 5.5A). However, they are only dropping the voltage from 12.3V to 8.5V. At the 13.5V running voltage, the radio will see over 9V. Is this to much for a tube radio to handle? Thanks for the info.

 

That's nearly a 50% increase over the intended input voltage. 7v would probably be okay, as that would have been close to the operating voltage originally. I think you'll be toasting tube filaments with that much voltage...

 

that might be too much for the filaments. Might be better off switching to 12v tubes instead of using the voltage reducer, or maybe rewire the filaments.

I'll let a more knowledgeable tube radio guy chime in now...

 

That is 2.5 more volts and it might burn out the tubes .

RetroJim

 

Thanks for the info, that's about what I figured I'd hear. I know my customer isn't going to want to pay for tube replacments, I guess I'll have to find higher quality voltage drops

 

Hi

I had Bob's Radio in Pismo Beach, CA redo the 6 volt radlio on my 1955 Imperal several years ago. At the time, he said if it had ever been used with an 8 volt battery forget it, it was ruined.

Jan in Ojai, CA
1952 Plymouth Suburban 392 hemi

 

Its not just a matter of popping in higher voltage tubes.That could lead to a FIRE

Try to find the device that will reduce your voltage also.

Oldmics

 

You might want to spend some time searching for threads discussing this, because I know we got some pretty good info about it a while back (less than a year ago).

 

Grab your battery and drive a nail in at 6 volts.

 

That will work, but will eventually screw up the battery. All the cells see the same voltage/current when it's charging. And the draw on the 3 cells that power the radio will be higher than the other 3. Eventually those 3 will not recover and will be low. Reducing the capacity of the whole battery.

There must be a Zener Diode type reducer availible (not a resistor) that could knock the voltage back to what the radio could handle.

 

Although my suggestion is tongue in cheek it actually could work - no different than center tapping a transformer and in fact there are commercially available batteries with 'in between' posts for intermediate voltages.

The battery is recharged across the entire thing, from Ohm's Law we know that the current is the same in a series circuit. The overall charging current would be affected by individual cells with a lower voltage (since their voltage would be lower); overall the charging self-corrects.

I agree that a voltage-regulating circuit is more efficient than a resistive arrangement.

The biggest problem with driving a nail into the battery would be in ensuring good electrical/mechanical contact where the damn nail hits the plates.

A really simple way of solving this problem is to run two six volt batteries in series. The 12 volt accessories and the alternator connect across the 12 volts. Your six volt devices connect across the second six volt battery (the one that goes to ground). Done.

 

This would work great, the hard part would be hiding the other battery.

 

Use two six volt Optimas. Same footprint as one 12 volter.

 

There are solid state voltage regulators available, or you might find a DC-DC converter (switching power supply) that will do the job.

A resistor is not the best way to drop voltage to something like a radio.

 

Why not just have the original radio converted . I had the original old RCA in the Faceldone a year or so ago . Changed over the entire internals to current technology , included MP3 compatability . Used the original case and controls . Cant tell from original until you take the radio apart.