Looking at rider 3-6, on the lower left corner there is a power supply unit. Is this required to get the radio playing or for different voltages,also the volume control 10,000 ohms with 250 ohm birs(?)live in US w /110 voltage.

Hi Bob

The volume control is 10,000 ohms with a stop at 250 ohms. That way cathode of the tube never goes to zero volts. If you need to change the control use one rated 10,000 ohms and add a 250 ohm (220 will do) in series with cathode of 39 tube.

http://www.nostalgiaair.org/Resources/197/M0004197.htm

Norm

:Looking at rider 3-6, on the lower left corner there is a power supply unit. Is this required to get the radio playing or for different voltages,also the volume control 10,000 ohms with 250 ohm birs(?)live in US w /110 voltage.

Hi; Any idea about the operation of this radio, it seems to me like something is missing, by just plugging in (110 V), it will not work. The schematic is not clear or I'm missing something..Rider 3-6

Bob

Should operate as drawn. The lower left ares, as you noticed, is for 220 volt operation.

They used 2 - 37 tubes are rectifiers. Probably no proper rectifiers were available at the time?

Do tubes light? If not check 280 ohm resistor shown on right side of the schematic. It will be large and may be open?

Norm

:Hi; Any idea about the operation of this radio, it seems to me like something is missing, by just plugging in (110 V), it will not work. The schematic is not clear or I'm missing something..Rider 3-6

Hi; The 280 ohm resistor tested ok, for some reason it was bleeding though to the chassis. Replacing,what should wattage be?? This little radio looks like lots of people worked on it from the past,has a nice case for travel guess I'll rewire and try to get working.

Norm; Radio is receiving great only question,replaced vol control,Bias question; 250 ohm resistor one side to pin #4 of 39 other end to ?? rider 3-6 DeWald

Hi Bob

Original control had a 250 ohm resistor built in so it could not go to zero ohms. This resistor should connect between tubes and control.

It will keep a min bias on tubes. At zero volts tubes will draw more current and could damage the control.

Norm

:Hi Bob
:
: The volume control is 10,000 ohms with a stop at 250 ohms. That way cathode of the tube never goes to zero volts. If you need to change the control use one rated 10,000 ohms and add a 250 ohm (220 will do) in series with cathode of 39 tube.
:
:http://www.nostalgiaair.org/Resources/197/M0004197.htm
:
:Norm
:
::Looking at rider 3-6, on the lower left corner there is a power supply unit. Is this required to get the radio playing or for different voltages,also the volume control 10,000 ohms with 250 ohm birs(?)live in US w /110 voltage.

Norm;If I'm reading schematic correctly 250 ohm resistor from pin 4 of 39 tube to volume control pin that is single other 2 pins on control are attached together