I know that this subject has been discussed many times, but I'm trying to determine the best way to replace the resistor line cord on a "Globe Trotter" radio which appears to be identical to the Balkeit model 45 chassis.

The set appears to originally have a 150 ohm resistor line cord, but if I'm not mistaken, 110v was the norm then. The tube lineup is 25Z5, 43, 6D6, 6C6. I can access the cord attachment the the globe base, but rather not put a big resistor in there. Is there a combination of diode/non polarized electrolytic/different voltage tubes that would be best for this radio??

Thanks in advance.

:I know that this subject has been discussed many times, but I'm trying to determine the best way to replace the resistor line cord on a "Globe Trotter" radio which appears to be identical to the Balkeit model 45 chassis.
:
:The set appears to originally have a 150 ohm resistor line cord, but if I'm not mistaken, 110v was the norm then. The tube lineup is 25Z5, 43, 6D6, 6C6. I can access the cord attachment the the globe base, but rather not put a big resistor in there. Is there a combination of diode/non polarized electrolytic/different voltage tubes that would be best for this radio??
:
:Thanks in advance.

Looking at my tube data book, I realize that I forgot that a 43 tube is a 25 volt tube. Therefore 25+25+6+6=62 volts; a voltage halving diode would be just about perfect. Am I wrong? Also, if I'm right and the diode is the way to go, which way do I install it?

Thanks again.

::I know that this subject has been discussed many times, but I'm trying to determine the best way to replace the resistor line cord on a "Globe Trotter" radio which appears to be identical to the Balkeit model 45 chassis.
::
::The set appears to originally have a 150 ohm resistor line cord, but if I'm not mistaken, 110v was the norm then. The tube lineup is 25Z5, 43, 6D6, 6C6. I can access the cord attachment the the globe base, but rather not put a big resistor in there. Is there a combination of diode/non polarized electrolytic/different voltage tubes that would be best for this radio??
::
::Thanks in advance.
:
:
:
:
:Looking at my tube data book, I realize that I forgot that a 43 tube is a 25 volt tube. Therefore 25+25+6+6=62 volts; a voltage halving diode would be just about perfect. Am I wrong? Also, if I'm right and the diode is the way to go, which way do I install it?
:
:Thanks again.

Michael: see if these articles are what you're looking for.
http://www.nostalgiaair.org/References/Articles/TheFlash/Flash01.htm
http://www.nostalgiaair.org/References/Articles/TheFlash/Flash09.htm
The nice thing about this solution is you avoid the heat build-up under the chassis that a resistor would generate.
Steve

A 1/2 wave rectifier will actual give you approximately an effective 84 volts equivalent.

However a "dropper capacitor" will work very well.

In the next link here...Read the following article... then use the link they offer at the very bottom of the text to get a copy of the spreadsheet utility to calculate for your exact radio needs.

http://www.vintage-radio.com/repair-restore-information/valve_dropper-calcs.html

A 1/2 wave rectifier will actual give you approximately an effective 84 volts equivalent.

However a "dropper capacitor" will work very well.

In the next link here...Read the following article... then use the link they offer at the very bottom of the text to get a copy of the spreadsheet utility to calculate for your exact radio needs.

http://www.vintage-radio.com/repair-restore-information/valve_dropper-calcs.html

I would use a diode plus a dropping capacitor.

Line cord resistors are unsafe and new replacements are not available.
Doug

:A 1/2 wave rectifier will actual give you approximately an effective 84 volts equivalent.
:
:However a "dropper capacitor" will work very well.
:
:In the next link here...Read the following article... then use the link they offer at the very bottom of the text to get a copy of the spreadsheet utility to calculate for your exact radio needs.
:
:http://www.vintage-radio.com/repair-restore-information/valve_dropper-calcs.html

As Peter says, a diode will NOT reduce the RMS voltage by half. It has to do with the power and the SQRT(2).
Doug

Doug... can you add a dropper cap like that after a diode makes DC?

Or are you suggesting dropping some AC with a cap first..THEN also using a 1/2 wave diode?

That makes little sense to me when the dropper cap alone will work perfectly.

What are you suggesting that I may be missing?

Peter: The diode and dropping cap would be in series. (The cap wouldn't be shunted across the line, like a filter cap.) The order wouldn't make a difference.

The dropping cap would not see DC - rather, it would see a half-wave current waveform, which would go through it, but be attenuated due to the capacitive impedance of the cap.

With the diode, the dropping cap would have to be a higher value than without the diode, but could be a lower voltage rating. I agree, nothing really to be gained, and it's mathematically complex. But it seems like I did that once, but can't recall why.
Doug

:Doug... can you add a dropper cap like that after a diode makes DC?
:
:Or are you suggesting dropping some AC with a cap first..THEN also using a 1/2 wave diode?
:
:That makes little sense to me when the dropper cap alone will work perfectly.
:
:What are you suggesting that I may be missing?
:
:

OK, I remember now what I did. I put a diode in series with a dropping resistor. The diode drops the RMS voltage to 70%, then the resistor does the rest. Less heating that way.

A series cap would do the same thing, but since it doesn't heat anyway, the diode wouldn't accomplish much.
Doug

:Peter: The diode and dropping cap would be in series. (The cap wouldn't be shunted across the line, like a filter cap.) The order wouldn't make a difference.
:
:The dropping cap would not see DC - rather, it would see a half-wave current waveform, which would go through it, but be attenuated due to the capacitive impedance of the cap.
:
:With the diode, the dropping cap would have to be a higher value than without the diode, but could be a lower voltage rating. I agree, nothing really to be gained, and it's mathematically complex. But it seems like I did that once, but can't recall why.
:Doug
:
:
:
:
::Doug... can you add a dropper cap like that after a diode makes DC?
::
::Or are you suggesting dropping some AC with a cap first..THEN also using a 1/2 wave diode?
::
::That makes little sense to me when the dropper cap alone will work perfectly.
::
::What are you suggesting that I may be missing?
::
::

:As Peter says, a diode will NOT reduce the RMS voltage by half. It has to do with the power and the SQRT(2).
:Doug