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.
RADIO BROADCAST ADVERTISER
421
NATIONAL
POWER AMPLIFIER,
Lynch Resistors, TOBE Condensers Electrad Royalty Resistances, all play their essential part in the excellence of the RATIONAL Power Amplifier.
"V/TOST good Radio sets today are sensitive and selective, but many have lagged behind in audio quality. The NATIONAL Power Amplifier brings your present set up-to-date, and makes its performance an unqualified pleasure. Designed in collaboration with Arthur H. Lynch and James Millen, it omits nothing to give quality reproduction.
This new instrument contains a complete audio amplifier of a design not hitherto offered to the public, which is arranged to be coupled directly to the detector tube of any receiver. The audio tubes are removed from the receiver and in their place the NATIONAL Power Amplifier passes the detected signal to the loud speaker at any desired volume, which may be sufficient to fill a large hall, still without any impairment of tone or quality.
The amplifier uses one stage of impedance and two of resistance coupling, with an impedance leak on the power tube. High-mu tubes are used for the first two stages and a UX-171 semi-power tube for the output, which passes through a NATIONAL Tone Filter to the loudspeaker. Exceptionally good results have been secured with CeCo Tubes in the amplifier, although other standard makes of high-mu and power tubes give excellent performance, providing their characteristics are approximately the same.
In addition to the audio amplifier, this new NATIONAL Power Amplifier has a com' plete B-supply for the entire set and the C-voltage for the power tube. Once adjusted it requires no further attention and may be placed in a cabinet beneath the Radio set.
The B-supply portion of the NATIONAL Power Amplifier is designed to be used either with filamentless full-wave rectifier tubes, preferably those which will supply from 80 to 85 mils — or the UX-213 or CX-313 fullwave Rectron Tube. All of the parts whether made by NATIONAL COMPANY or other manufacturers, have been selected only after careful investigation— so as to maintain NATIONAL standards of excellence in this sturdy and thoroughly well designed pie:e of apparatus.