. QST . ltage wave and the July 1955 23 output-voltage wave when the circuit was ad-justed for 10-kc. separation of the markers. Notethat the frequency ratio in Fig. 3A is clearly 31to 10. The adjustment of either Ci or C2 is rathercritical because the frequency of the tuned circuitmust be within a few hundred cycles of 310 found it advisal)le to use a cathode-followerbuffer after the oscillator circuit to avoid detun-ing when we changed loads. Adjusting the funda-mental to exactly 100 kc. is also critical, becausetuning the LC circuit pulls the crystal a littleand it is necessary to rea
. QST . ltage wave and the July 1955 23 output-voltage wave when the circuit was ad-justed for 10-kc. separation of the markers. Notethat the frequency ratio in Fig. 3A is clearly 31to 10. The adjustment of either Ci or C2 is rathercritical because the frequency of the tuned circuitmust be within a few hundred cycles of 310 found it advisal)le to use a cathode-followerbuffer after the oscillator circuit to avoid detun-ing when we changed loads. Adjusting the funda-mental to exactly 100 kc. is also critical, becausetuning the LC circuit pulls the crystal a littleand it is necessary to readjust C3. Adjustment Procedure For our experimental work we had availablerather ideal equipment in the way of syncro-scopes and frequency counters, but the unit hasbeen adjusted from scratch and used in the homestation with very satisfactory results. The bestprocedure is to establish oscillation, and adjusteither or both Ci and C2 until clean markers areheard on the station receiver at 100-kc. Iifi. 3 — Oscillograms obtained when circnit is ail-jiisted for 10-kc. markers. A — Grid voltage. B — Out-|Mit voltage. Then tune the receiver to the approximate pointwhere the subinterval marker is desired andadjust either or both Ci and C2 until a clear,clean marker is heard. No difficulty at all wasexperienced in getting markers every 20 kc,but for closer intervals one should check thatt here are the required number between the previously noted. After the marker inter-vals have been established, zero-beat with \\\\ Vby adjustment of ^3. TABLE I Frequency of Ratio of Tuned Separation Tuned Circuit, Circuit and Crystal of Markers, Kc. Frequencies Kc. 7 to 2 50 333 J^ 10 to 3 33 H 325 13 to 4 25 320 16 to 5 20 316% 19 to 6 16% 314^ 22 to 7 25 to 8 28 to 9 310 31 to 10 10 Construction The unit shown in the photographs includes acathode-follower buffer stage and a built-inpower supply with voltage regulation. The cir-cuits of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
