Radio Broadcast (Nov. 1925-Apr 1926)

APRIL, 1926 A PORTABLE B BATTERY TRANSMITTER 681 BACK VIEW SIDE VIEW -Flexible Connection END VIEW OF CAM Rubber Handle TABLE OF AUDIBILITY SIGNS Rl R2R3R4R5R6R7 R8 R9 -Faint signals, just audible -Weak signals, barely readable -Weak signals, but readable -Fair signals, easily readable -Moderately strong signals -Strong signals -Good strong signals. Would be readable through heavy qrn and qrm -Very strong signals. "Several feet-from-phones signals" -Extremely strong signals Right Angle Bracket ^ Switch Jaw RJH.Screw.^ R.H.Wood Screws --' FIG. 6 Details of the throw-over switch which changes the antenna and batteries from sending to receiving .F.H.Screw LATORS installed Panel DETAIL OF SWITCH JAW well insulated as possible, and an accompanying photograph shows some Pyrex insulators made by the Corning Glass Works which are now being installed at 2 gy. Coupling to the antenna should be loose enough so that the tube continues to oscillate under all conditions. If coupling is too close, the wavelength will jump about and no listening operator can read what you are trying to send. On 40 meters, reception is erratic, fading is bad, but phenomenal distances can be attained with low powers. On 80 meters transmitting distances are not so great, but steady signals, good traffic handling, and the possibility of phone transmission make it a very interesting band in which to work. A few words about 9 ccq may not be amiss to show that the work done between that station and 2 gy is not due to unusual conditions but rather to the great carrying power of transmissions on 40 meters with pure d. c. plate supply. Station 9 ccq is operated by Mr. Vere Davis at Braymer, Missouri, about 1080 miles from Garden City. Braymer is 60 miles East of Kansas City and 20 miles southwest of Chillicothe in rolling country which is still blessed with considerable timber. Mr. Davis says he "became interested in broadcast radio about three years ago and it's just a case of drifting from bad to worse, I guess. Have had an amateur's license now about four or five months and have been active about two and one-half. I became interested in amateur radio just about the same way most anybody of my age and interests does. I've always read radio magazines when I got the chance Radio Broadcast Photograph and of course couldn't help seeing short wave circuits and the marvelous things they were supposed to do. I made my first successful short wave receiver last spring, a little less than a year ago, with the intention first of listening to the short wave broadcasts and was very disappointed when kdka came in strong but with badfad -2 .002 mfd in series ing and distortion. So another fan, now 9 cjd, and I began practicingthe code, and to our surprise passed the amateurs' examination. My first communication waswith 9 wq at Elmhurst, Illinois (40 meters)^ at about 4 o'clock p. m. November 1st. Next was 9 bv at Council Bluffs, Iowa,, and the third was 8 cjm, Elyria, Ohio, but I found trouble raising stations. I could get a large current in the antenna but it wasn't effective. In a month or so I got time to improve the system and although I don't get the current I did, reports are better now. Have been reported at 5 aqi, Meridian, Mississippi, R 6 at about noon. Plate voltage 220, mils., 33." Since the International Tests, this simple transmitter has been in operation at 2 gy with complete success, reports indicating that the pure d.c. note penetrates much better than our "high powered" outfit, for distances up to 1000 miles. The operators at 2 gy welcome reports of reception and will be glad to advise any of Radio Broadcast's readers who are interested in low power, short wavelength amateur work. 50 Turns v.0M0.0.0.Q.0.HgM 3"diam. 28 d.c.c: MA o Q O O in o in switch fig. 5 The complete Hartley circuit used in the transmitter ANT. GND