Radio Digest (Oct 1923-July 1924)

RADIO DIGEST — Illustrated February 2, W2U RODYNE RECEIVER (Continued from page Z\) dered and knowing even less than be did before. In boring underground, In tunnels or subways, to run under streams or bodies of water, there is likely to be a ant seepage or inflow of water. This inflow of water is naturally due to the pressure Of the stream above it. A method employed in work of this nature is the counteracting air pressure in the excavation, sufficient to overcome the natural external pressure. To compare this, then, with the situation in Radio frequency circuits, we would state that there is a leakage, or what might be termed a detrimental pressure, mainly between the grid and plate of each tube. In addition, we have considerable leakage throughout the windings of the transformers, the wiring of the set and in numerous other parts of the apparatus. Now. if there can be created a counterpressure that exactly balances the detrimental pressure or leakage, we have balanced the set. If the counterpressure is insufficient, we have only partially remedied the trouble, whereas if our counterpressure is too great we have introduced a new trouble. We find, therefore, that neutralization, unless properly adjusted, is valueless and might even be detrimental.' Balancing Operation Light first four tubes and plug receivers in on first audio jack. Tune in for reception, but avoid any near local station where the volume is very great. The reception should be clearly heard but not so loudly as to make it uncomfortable to the ears. Remove the second tube from the socket and insert a piece of paper under one of the filament contacts, then replace the tube in the socket. Although the rheostat is turned on, the filament naturally will not light. Don't turn off the rheostat; the real balancing should neutralize all capacity effects, even the filament battery leads; hence the method used. With this tube inoperative, reception will still be heard faintly in the receiver due to the capacity coupling that exists and which is to be neutralized. If the dials are slightly readjusted, the volume can usually be increased a trifle. This step is now ready for balancing. The adjustment is made on the second neutrodon. The adjustment is varied until the reception is entirely eliminated or reduced to minimum volume. If the volume of the reception is too great, it will be very difficult to judge this point. The dial adjustment should then be gone over to see if readjustment does not bring back the reception. If so. the balancing operation will have to be repeated. After the adjustment is complete on this neutrodon it should be looked by some means. Take out the tube, remove the paper, then replace the tube and again re tune the set. The procedure is then repeated with the first tube and the first neutrodon. (TO BE CONTINUED.) KING MILOPLEX (Continued from page 19) else does you father do with his pen and ink? Please tell him he can buy them already printed at the dime store." Teachers are so considerate — the fussy cats — and this repartee goes for the one that used to make me write "Dear Teacher" 500 times after school. Well, lady, this boy eats and he doesn't come by it honestly either — he may take after me — but usually is three square meals ahead. Well, you know "growing children, growing pains" or is it "hungry to bed, hungry to rise, if your cook won't feed you, advertise," and then "try and get it." Both of the above are not original but old truisms from the almanac, though they tell me that if you now ask a druggist for an almanac he starts sniffling to see if you are still wearing your "aesonfoetedia" (or however you spell it) bag, that smells like garlic — but it hain't. I'm not going to have my hair hennaed this winter — was going to but think I'll look better with a Joan of Arc hair cut. You know the kind I mean, one of those you plaster down with water that makes you look like an Eskimo bride. And now, ladies, may I step out of the Mystery Man character long enough to assure you both my good wife Maggie, whose real pet name is Tude, and myself would be ungrateful indeed, did we not assure each and everyone — the oh! so many who have written us — that we deeply appreciate the sincere well wishes and interest you have so lavished upon us, in order that he, your sweetheart, may still belong to "My Gang." Many seem to feel that Radio is to me an open book — they seekers for the light. Yet, truthfully, to me it is ever mysterious, ever a will-o'-the-wisp, a fairy tale. To me the bugaboo of static, the scratches, the howls mean nothing but another proof of our intellectual weakness. Because we see, we look not; because we feel, the sense of touch is commonplace; but to hear and to realize so inanimate an object truly "man-made" can be commanded to do our will, can reproduce with fidelity sounds originating hundreds of miles, yes SUPER VALUESGENUINE Fada-Hazeltine Neutrodyne Parts FOR 5 TUBE SET List Price $65.60 OUR PRICE $50. 1 S You Save $15.45 by Buying Through Us RESISTANCES Genuine P. L. Original Lavite 48,000 OHMS, . $1.00 100,000 OHMS $1.00 We Are Prepared to Supply Dealers. Write for Our Proposition. We Have Just Received a New Shipment of THE NEW MODEL D, N. & K. PHONES MADE IN GERMANY Our Price $6.50 ... Si*!; 9l^f„A 20 " D'SCOUNT On All Standard Radio Apparatus Not Listed Above ALL MAIL ORDERS SHIPPED PROMPTLY. SEND MONEY ORDER. INCLUDING POSTAGE. The RADIO MAIL ORDER HOUSE— Known for Low Prices. Write for Our Catalog B HAN even thousands, away is positively uncanny. Scratches, cat calls, anything — they are truly marvelous conceptions. Last week I promised the Reflex, but (the man who invented that word was a life guard) just as I was about to run it, I discovered another hardworking experimenter had been working on the same klea and published a circuit so near like mine that I fear I would be accused of cheating if I ran it. 8b XIX on the reflex other than to say those getting my picture will also receive the circuit and I xcill gladly mail it to all who u-iU send a stamped self-addressed envelope. Atta baby ! Let's eat. (TO BE CONTINUED.) F*or Clear Reception By placing a .001-mfd. fixed condenser between the grid leak on the secondary of the second audio-frequency transformer and the negative side of the filament of the first tube, clearer and sometimes louder reception will be obtained. Trouble Caused by Dust on Plates of Condenser Dust (as well as pieces of solder and stray bits of insulation, etc.), accumulates very quickly between the plates of variable condensers, and aside from the annoyance which the knowledge of its existence gives, it has several undesirable electrical effects. It increases the dielectric loss, reducing the efficiency of the apparatus, and under certain meteorological conditions the tiny particles accumulate static charges, which, in discharging, add to the sounds caused by the prevailing atmospheric disturbances. In low power bulb transmitters, where receiving variable condensers are often shunted across high potentials, an accumulation of dust often leads to the breakdown of the condenser. The dust and other accumulations can be swept away by a pipe cleaner (the kind sold in cigar stores at 5 cents a package) inserted between the plates. 3 WEST 39th STREET, NEW YORK CITY IMMMM Radiotron UV-199 A Small Tube That's a Big Performer Radiotron UV-199 for detection or amplification $5.00 This symbol of quality is your protection The new UV-199 is proving a mighty popular member of the Radiotron family, particularly for portable sets. For quiet operation — great ruggedness — uniform operation Radiotron UV-199 is unsurpassed. Each new Radiotron has marked a big step in radio advancement. The RCA mark is the foundation of radio growth — and your protection when you buy. Ask for Radiotrons — and look for the mark. Radio Corporation of America Sales Offices — Dept. 311 233 Broadway, New York 10 South LaSalle St., 433 California St., Chicago, 111. San Francisco, CaL Radiotrons REG. 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