Stewart Warner model 300

Which tubes can be used in this model? Riders do not specify them!

You can check out this link .
Dan in Calgary.

https://www.radiomuseum.org/r/stewart_wa_300.html

Type '01a, also called: 201a, 301a, can be "S" bulb (also called globe or balloon), or the "ST" envelope. These are 1/4 amp filament tubes. This series of tubes has thoriated filament, they can be rejuvenated most of the time.

Do not mix or use 01 tubes, these are 1 amp tubes, these will cause the filament rheostats to burn out. They have pure tungsten filaments and cannot be rejuvenated.

The base pins in old tubes often corrodes and the connection is lost, re-soldering the pins will fix. Do not overheat pins, Bakelite will blister and the pin will get loose.

Use 6.3 to 6.6 volt for the "A" filament from a supply capable of at lest 3 amps if line powered, if a lead/acid battery it should be 60 to 90 amp hours.

A high impedance speaker must be used. Or a 5k audio output transformer and a conventional 4 ohm speaker. If headphones they must be high impedance too.

A DC measurement of the speaker or headphones should be from 1000 to 5000 ohms with an analog meter.

http://www.nostalgiaair.org/pagesbymodel/794/M0029794.pdf

Most 20's era battery sets have audio transformer or connection failures, almost always repairable.

Chas

Thank you for your information! Regards from sunny Brazil!