150T

After working at Heintz & Kaufman, Bill Eitel, W6UF and Jack McCullough, W6CHE had engineered their first own product, known as 150T, followed by 35T, 50T, 300T, 500T, 100T etc.

During the development of the HK354 at H & K they had realized that the ideal transmitting tube of that time should be an extremely "hard" tube with a thoriated tungsten filament, Nonex glass bulb, cylindrical elements supported by the bulb with no internal ceramic insulators which could be a source of arc-over and plate and grid made of tantalum which could be made almost entirely free of gas so the tube need not have a "getter". The 150T was first advertised in QST in 1934 and was exhibited at the ARRL Convention 1934 in Sacramento. After that the tube was produced in series