We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
SEPTEMBER, 1927 THE NEW A. C. TUBES 285 1600 16.000 1400 14.000 1200 12,000 1000 10.000 600 6.000 !AD10 BROADCAS LABORATORY C-327 £,.2.5 Kfla X Heater 8-Ohm Pot. IMPORTANT CONSTANTS OF THE 0-327 (ABOVE) ANDC-326 (BELOW) PLOTTED AGAINST GRID VOLTAGE 17.000 16.000 15.000 14.000 ^ 13.000 „ 12.000' o 11.000 10.000 9000 RADIO BIIMDCAST \.x c --xt "E P «I o 10 1200 1100 ,000? 1 I 2 MO", -» 20 2.5 3.0- 12,000 1800 1700 10,000 1600 g 1500 8,000° • 1400 1300= 6,000 1200 a o 1100 4,000 1000 900 EJ.-IP CURVES FOR C-326 (ABOVE) AND r MARATHON HIGH-MU TUBE (BELOW) HOW THE CONSTANTS OF C-327 VARY WITH HEATER VOLTAGE It is a heater type, the heater current being about 0.35 amperes at 15 volts. The heater is a rather heavy carbon filament which at the top is electrically connected to the cathode. This makes it pos- sible to use a standard four-prong base—an obvious advantage which other heater tubes do not possess. The R. C. A. and Cunningham heater tubes require a special five- prong base, while the others, of which the McCullough is the prototype, have two heater term- inals at the top of the tube, or at the side, to which are attached the a.c. terminals. We noted at the Chicago Radio Trade Show that 35 per cent, of CONSTANTS OF C-326 AND 0-327 AS RELATED TO PLATE VOLTAGE the receivers shown were a.c. operated. Not many of these sets used a.c. tubes, but used some other method of eliminating hum when using standard d.c. tubes. All in all, the a.c. tube is some- thing to watch. It is still in the development stage, and the work of many tube engineers and chem- ists will be involved before the final answer is ready. The a.c. tube is not destined to supplant the present type of tube we all use in the next six months or in any other period so short. As soon as the Laboratory gets more data on the operation of the new tubes, they will be made avail- able. p-Ip CURVES OF MCCULLOUGH A. C. TUBE p-Ip CURVES FOR C^