"Advance" Set

Radio Record, Volume V, Issue 14, 16 October 1931, Page 30

"Advance" Set

SEVERAL correspondents have ine quired regarding the special broadeast coils for the "Advance" shortwave set described in the "Radio Guide." In the second edition certain changes have been made, so, to acquaint constructors with these,-we are reproducing portion of the second edition — relating to the.-coil. ONE tapped coil for each stage will bring in all stations from about 200 to 500 metres. The diagram gives all the information required. The tappings are altered: by pin and sockets. The top of each coil is a circle slightly larger in diameter than the coil, with an extension at the left-hand to accommodate the sockets, 1-8in. or 3-16in. ebonite being used, and secured to the top of the coil with celluloid cement. No. 3 tap on each coil includes 7Zl as the highest and 2BL as the lowegsy. station, readings on both dials

almost equal. No. 2 tap on each coil includes 4QG down to.below 3YA, while No. 2 rf. and No. 1 detector go down to 2NC, and changing to No. 1 r.f. reaches a few small stations below. Few changes are necessary to cover the whole broadcast band, and good reception is assured. Gauges of wire (s.w.g.) are 28 for the vf. and 386 for the detector, both ‘enamelled and quite closely wound. At each tap clean din. and twist into a small loop round a i-inch nail. The rf. coil is 2in. in diameter, of celluloid, bolted on a valve-base reduced to 3-8in. high. The detector coil former is made by rolling celluloid round a complete valve-base, at the same time cementing the two; at the top end place the ring sawn off the (Concluded at foot of previous column. )

y.f. coil, overlap and celluloid din. with cement, wrap twine over the whole length and set to dry; scrape the joint with a knife to remove the ridge. Cut the celluloid 3-8in. high for both coils, The aerial coil is 30 turns of 26. enamel wound on a lin. collar of celluloid to drop inside the r.f. coil and ‘rest at the bottom: connect top end to earth and bottom to aerial prong through holes in bottom of r.f. coil. Bottom of r.f. coil connects to gridpin and top is the highest tapping. Connect the arm to earth inside the coil. Inside connecting wires must be put iu before the top is cemented on.