. QST . ptionis not as great as can be expected from a smallsuperheterodyne using several tuned circuits ina 455-kc. ampUfier. However, you can makeup a lot of this selectivity by decreasing theantenna coupling and running the detector justunder the oscillation point. A strong signal de-creases the selectivity of the regenerative de-tector, hence the need for reducing the signalby decreasing the antenna coupling. phoneis received the same as a signal, by advancmgthe regeneration control past the oscillation pointand tuning carefully about the signal until itbecomes intelligibl
. QST . ptionis not as great as can be expected from a smallsuperheterodyne using several tuned circuits ina 455-kc. ampUfier. However, you can makeup a lot of this selectivity by decreasing theantenna coupling and running the detector justunder the oscillation point. A strong signal de-creases the selectivity of the regenerative de-tector, hence the need for reducing the signalby decreasing the antenna coupling. phoneis received the same as a signal, by advancmgthe regeneration control past the oscillation pointand tuning carefully about the signal until itbecomes intelligible. Overload is again yourenemy here, so run the antenna coupling at avalue consistent with good signal/noise ratio. The mixer input and high-frequency oscillator coils aremounted on tie points, asshown here. The antenna coil,Li, is mounted on the end of apiece of lucite rod, as shownhere and in Fig. 2. The leadsto it are wrapped several timesaround the rod, to provide apig tail connection. September 1955. Upper-Air Conditions for Two-Meter DX Temperature and Water-Vapor Content Soundingsfor Some Famous Dates BY JAMES S. COLLIER.* W20BB THE man is well aware that a tem-perature inversion, steep water vaporgradient or some such thing is necessaryfor tropospheric propagation of his signals overextraordinary distances. W2BAV in his article, Painless Predictionof Two-Meter Band Openings {QST, October,1919), pointed out the correlation between sur-face weather conditions and some good 2-meteropenings. Similarly, this article will show thevertical distribution of temperature and moisturefor times of good 2-meter DX. Consider first the variation of temperatureand water vapor wnth height as shown in Fig. are no temperature inversions (that is, an 12,000 ■ ^^■^^\ \ K^ 10,000 k 8,0001 ()\ \ (3 4) \ \ ^ 6,000 :;4 0oo ^ 2,000 C4 o\ \ (5 0)\ \WATER VAPOR \ \(63)\ \ TEMPERATURE 0 . ^ C7 5)\ \ . - 5 O 5 10 15 20 TEMPERATURE (°C) f^S- I — L. S. Standard Atmosphere tempe
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
